Lithium-containing glass

Abstract

The invention relates to lithium-containing glasses. A glass article comprising, in terms of oxide, from 60 mol% to 74 mol% SiO2, from 7 mol% to 18 mol% Al2O3, from 3 mol% to 16 mol% B2O3, from 0 mol% to 6 mol% Na2O, from 0 mol% to 5 mol% P2O5, from 5 mol% to 11 mol% Li2O, less than or equal to 0.2 mol% SnO2, and from 0.5 mol% to 6.5 mol% divalent cation oxide. The glass article has a molar ratio Al2O3: (R2O + RO) of greater than or equal to 0.9, where R2O is the sum of alkali metal oxides (in mol%) and RO is the sum of divalent cation oxides (in mol%).

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 62 / 418367, filed November 7, 2016; U.S. Provisional Application Serial No. 62 / 452004, filed January 30, 2017; and U.S. Provisional Application Serial No. 62 / 565190, filed September 29, 2017, based on 35 USC § 119, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This specification generally relates to low-viscosity glass and lithium-containing glass. More specifically, this specification relates to the manufacture of low-viscosity glass and lithium-containing aluminum silicate glass that can be used as cover glass. This specification also relates to low-viscosity lithium-containing aluminum silicate glass containing fusion lines. Background Technology

[0004] The mobile nature of portable devices (e.g., smartphones, tablets, portable media players, personal computers, and cameras) makes them particularly vulnerable to accidental drops onto hard surfaces (e.g., the ground). These devices often incorporate a cover glass that can be damaged upon impact with a hard surface. In many of these devices, the cover glass serves to cover the display screen and may also incorporate touch functionality, thus negatively impacting the device's usability when the cover glass is damaged.

[0005] When a portable device is dropped onto a hard surface, the glass covering exhibits two main failure modes. One mode is flexural failure, caused by the glass bending under dynamic loads from an impact with a hard surface. The other mode is sharp-contact failure, caused by introducing damage to the glass surface. Impacts from rough, hard surfaces (e.g., asphalt, granite, etc.) can leave sharp indentations on the glass surface. These indentations become failure sites on the glass surface, potentially leading to crack initiation and propagation.

[0006] Ion exchange technology, which involves inducing compressive stress in the glass surface, can make glass more resistant to flexural failure. However, ion-exchanged glasses remain vulnerable to dynamic sharp contact due to high stress concentration caused by localized indentations in contact with sharp objects.

[0007] Glass manufacturers and handheld device manufacturers continue to strive to improve the resistance of handheld devices to sharp contact failure. Solutions range from coatings on the cover glass to bevels that prevent the cover glass from directly contacting a hard surface when the device is dropped onto a hard surface. However, due to aesthetic and functional requirements, it is very difficult to completely prevent the cover glass from contacting a hard surface.

[0008] It is also desirable for portable devices to be as thin as possible. Therefore, in addition to strength, it is desirable to make the glass used as a cover glass in a portable device as thin as possible. Therefore, in addition to increasing the strength of the cover glass, it is desirable for the mechanical properties of the glass to allow it to be formed by processes that enable the manufacture of thin glass articles, e.g., thin glass sheets.

[0009] Glass forming apparatuses are commonly used to form various glass products, such as glass sheets for LCD displays, portable devices, and the like. These glass sheets can be manufactured by flowing molten glass down a forming wedge to form a continuous glass ribbon. Developing technologies use glass compositions with decreasing liquidus viscosities. As such, higher forming temperatures are used to prevent devitrification from occurring as the molten glass passes through the forming wedge.

[0010] Therefore, there is a need for alternative methods and apparatuses for forming glass ribbons that can provide higher forming temperatures to mitigate devitrification for glasses with lower liquidus viscosities. Therefore, there is also a need for glasses that can be strengthened, e.g., by ion exchange, and have mechanical properties that allow them to be formed into thin glass articles. SUMMARY

[0011] According to some embodiments, the glass article comprises, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 74 Si02, greater than or equal to 7 to less than or equal to 18 AI2O3, greater than or equal to 3 to less than or equal to 16 B203, greater than 0 to less than or equal to 6 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, less than or equal to 0.2 Sn02, and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide. The glass article has a molar ratio AI2O3:(R20 + RO) that is greater than or equal to 0.9, where R20 is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent.

[0012] According to some embodiments, the glass article comprises, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 66 Si02, greater than or equal to 11.5 to less than or equal to 18 AI2O3, greater than or equal to 3 to less than or equal to 8 B203, greater than or equal to 2 to less than or equal to 6 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide. The glass article has a molar ratio AI2O3:(R2O + RO) greater than or equal to 0.9, where R2O is the sum of alkali oxide in mole percent and RO is the sum of divalent cation oxide in mole percent.

[0013] According to some embodiments, the glass article comprises, in mole percent on an oxide basis: greater than or equal to 65 to less than or equal to 74 Si02, greater than or equal to 7 to less than or equal to 12 AI2O3, greater than or equal to 5 to less than or equal to 16 B203, greater than or equal to 0 to less than or equal to 4 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide. The glass article has a molar ratio AI2O3:(R2O + RO) greater than or equal to 0.9, where R2O is the sum of alkali oxide in mole percent and RO is the sum of divalent cation oxide in mole percent.

[0014] According to some embodiments, the glass article comprises Li20, Si02, AI2O3, and a liquidus viscosity less than or equal to 300 kP, where R1 经退火 - R1 刚形成 is greater than or equal to 0.0003, where R1 经退火 is the refractive index of the glass heated for 1 hour at the annealing point of the glass at a wavelength of 589 nm, and R1 刚形成 is the refractive index of the as-formed glass at a wavelength of 589 nm.

[0015] According to some embodiments, a consumer electronic product includes a housing having a front surface, a back surface, and side surfaces; an electronic assembly provided at least partially within the housing, the electronic assembly including at least a controller, a memory, and a display, the display being provided at the front surface of the housing or adjacent to the front surface of the housing; and a cover substrate disposed over the display. At least one of the housing or a portion of the cover substrate includes the glass article of any one of the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment described above.

[0016] In other embodiments, the glass article comprises S1O2, AI2O3, B2O3, Li2O, Sn02, and a fusion line. The glass article can also comprise Na20 or P2O5. In some embodiments, the glass article comprises, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 74 S1O2, greater than or equal to 7 to less than or equal to 18 AI2O3, greater than or equal to 3 to less than or equal to 16 B2O3, greater than 0 to less than or equal to 6 Na20, greater than or equal to 0 to less than or equal to 5 P2O5, greater than or equal to 5 to less than or equal to 11 Li2O, and less than or equal to 0.2 Sn02. In some embodiments, the glass article comprises a molar ratio of AI2O3:(R2O + RO) that is greater than or equal to 0.9, where R2O is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent. In some embodiments, the glass article comprises a liquidus viscosity that is less than or equal to 300 kP, less than or equal to 100 kP, less than or equal to 50 kP, or less than or equal to 25 kP. In some embodiments, the glass article is strengthened by an ion exchange process to form a compressive stress layer on at least one surface of the glass article. In some embodiments, the glass article comprises a depth of compression that is greater than or equal to 0.15t, where t is the thickness of the glass article. In some embodiments, the glass article comprises a depth of compression (DOC) that is greater than or equal to 0.15t to less than or equal to 0.25t, where t is the thickness of the glass article. In some embodiments, the glass article comprises a central tension that is greater than or equal to 30 MPa to less than or equal to 150 MPa. In some embodiments, the glass article is strengthened by an ion exchange process that adds potassium ions to the glass article and the potassium depth of layer (DOL) is greater than or equal to 5 pm to less than or equal to 30 pm. In some embodiments, the glass article comprises a compressive stress layer having a compressive stress at its surface that is greater than or equal to 300 MPa to less than or equal to 950 MPa. In some embodiments, the glass article comprises a Knoop scratch lateral crack threshold that is greater than or equal to 5 N to less than or equal to 24 N. In some embodiments, the glass article comprises an indentation fracture threshold that is greater than or equal to 15 kgf.

[0017] In other embodiments, the glass article comprises S1O2, AI2O3, and a liquidus viscosity less than or equal to 100 kP, less than or equal to 50 kP, or less than or equal to 25 kP. In some embodiments, the glass article comprises, in oxide mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 74 S1O2, greater than or equal to 7 to less than or equal to 18 AI2O3; greater than or equal to 3 to less than or equal to 16 B2O3, greater than 0 to less than or equal to 6 Na2O, greater than or equal to 0 to less than or equal to 5 P2O5, greater than or equal to 5 to less than or equal to 11 Li2O, and less than or equal to 0.2 SnO2. In some embodiments, the glass article is strengthened by an ion exchange process to form a compressive stress layer on at least one surface of the glass article. In some embodiments, the glass article comprises a depth of compression greater than or equal to 0.15t, where t is the thickness of the glass article. In some embodiments, the glass article comprises a depth of compression (DOC) greater than or equal to 0.15t to less than or equal to 0.25t, where t is the thickness of the glass article. In some embodiments, the glass article comprises a central tension greater than or equal to 30 MPa to less than or equal to 150 MPa. In some embodiments, the glass article is strengthened by an ion exchange process that adds potassium ions to the glass article, and the potassium depth of layer (DOL) is greater than or equal to 5 pm to less than or equal to 30 pm. In some embodiments, the glass article comprises a compressive stress layer having a compressive stress at its surface greater than or equal to 300 MPa to less than or equal to 950 MPa.

[0018] In other embodiments, the glass article includes at least Li20, and one or more of Si02, AI2O3, B203, and Sn02, and further includes a fusion line. In some embodiments, the glass article includes Na20 or P205. In some embodiments, the glass article includes, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 74 Si02, greater than or equal to 7 to less than or equal to 18 AI2O3, greater than or equal to 3 to less than or equal to 16 B203, greater than 0 to less than or equal to 6 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, and less than or equal to 0.2 Sn02. In some embodiments, the glass article includes a molar ratio of AI2O3:(R20 + RO) that is greater than or equal to 0.9, where R20 is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent. In some embodiments, the glass article includes a liquidus viscosity that is less than or equal to 300 kP, less than or equal to 100 kP, less than or equal to 50 kP, or less than or equal to 25 kP.

[0019] In other embodiments, the glass article includes Si02, AI2O3, Li20, and further includes a liquidus viscosity that is less than or equal to 100 kP and a fusion line. In some embodiments, the glass article includes a liquidus viscosity that is less than or equal to 50 kP or less than or equal to 25 kP. In some embodiments, the glass article includes, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 74 Si02, greater than or equal to 7 to less than or equal to 18 AI2O3, greater than or equal to 3 to less than or equal to 16 B203, greater than 0 to less than or equal to 6 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, and less than or equal to 0.2 Sn02. In some embodiments, the glass article is strengthened by an ion exchange process to form a compressive stress layer on at least one surface of the glass article.

[0020] Additional features and advantages are described in, and will be apparent from, the following DETAILED DESCRIPTION in conjunction with the drawings, in which like reference numerals designate the same or

[0021] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and, together with the description, serve to explain the principles and operations of the claimed subject matter. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 schematically showing an apparatus for forming a glass ribbon in accordance with one or more embodiments shown and described herein;

[0023] Figure 2 schematically showing a cross-sectional perspective view of the apparatus of Figure 1 at the location of line 3-3;

[0024] Figure 3 schematically showing a front perspective view of an apparatus for forming a glass ribbon of Figure 2 in accordance with one or more embodiments shown and described herein;

[0025] Figure 4A schematically showing an alternative heating cylinder for an apparatus for manufacturing glass in accordance with one or more embodiments shown and described herein;

[0026] Figure 4B schematically showing a cross-sectional view of the alternative heating cylinder along Figure 4A line 4B-4B of

[0027] Figure 5 schematically showing a rear perspective view of the alternative heating cylinder of Figure 4A in accordance with one or more embodiments shown and described herein;

[0028] Figure 6 illustratively showing a mathematical model of a root temperature response to a single power change for a heating cylinder comprising a molybdenum disilicide-containing heating element as described herein;

[0029] Figure 7 schematically showing another embodiment of a forming vessel of a glass manufacturing apparatus in accordance with one or more embodiments shown and described herein, the heating cylinder disposed proximate to a trough of the forming vessel;

[0030] Figure 8 schematically showing a cross-sectional view of the forming vessel of Figure 7 along line 8-8 in accordance with one or more embodiments shown and described herein;

[0031] Figure 9Another embodiment of a forming vessel of a glass manufacturing apparatus according to one or more embodiments shown and described herein is schematically shown, with a heating cylinder arranged proximate to a trough of the forming vessel;

[0032] Figure 10 is a partial cross-sectional perspective view of a fusion down-draw apparatus;

[0033] Figure 11 is a side elevation view of an embodiment of a system for drawing sheet glass comprising a set of edge rolls;

[0034] Figure 12 is a side elevation view of an embodiment of a system for drawing sheet glass comprising a first set of edge rolls and a second set of edge rolls;

[0035] Figure 13 shows a glass manufacturing apparatus according to one exemplary embodiment of the disclosure;

[0036] Figure 14 is a side view of a glass manufacturing apparatus according to one exemplary embodiment of the disclosure; Figure 13

[0037] Figure 15 is a top view of a glass manufacturing apparatus according to one exemplary embodiment of the disclosure at a first elevation; Figure 13

[0038] Figure 16 is a top view of a glass manufacturing apparatus according to one exemplary embodiment of the disclosure at a second elevation; Figure 13

[0039] Figure 17 is a top view of a glass manufacturing apparatus according to one exemplary embodiment of the disclosure at a third elevation; Figure 13

[0040] Figure 18 shows a glass manufacturing apparatus according to one exemplary embodiment of the disclosure;

[0041] Figure 19 is a top view of a glass manufacturing apparatus according to one exemplary embodiment of the disclosure at an intermediate elevation; Figure 18

[0042] shows an example diagram of independent constant force input control at two different elevations according to an exemplary embodiment of the disclosure; Figure 20

[0043] Figure 21 shows an example diagram of the forces experienced by the lowest draw rolls according to an exemplary embodiment of the disclosure;

[0044] ​​​​​Figure 22 Example diagram showing the minimum speed of the drawing roller according to an exemplary embodiment of the present disclosure;

[0045] Figure 23 The schematic diagram shows a cross-section of a glass having a compressive stress layer on its surface according to the embodiments disclosed herein;

[0046] Figure 24 The graph shows the results of the Knoop scratch transverse cracking threshold test of glass articles according to the embodiments disclosed herein;

[0047] Figure 25 The graph shows the indentation fracture threshold test results of glass articles according to the embodiments disclosed herein;

[0048] Figure 26A It is a plan view incorporating an exemplary electronic device of any glass article disclosed herein;

[0049] Figure 26B yes Figure 26A A perspective view of an exemplary electronic device;

[0050] Figure 27 yes Figure 2 A cross-sectional perspective view of the fusion pull-down device; and

[0051] Figure 28 yes Figure 2 Another cross-sectional perspective view of the fusion pull-down device. Detailed Implementation

[0052] Now, specific reference will be made to the manufacturing systems and processes used to produce such low-viscosity glasses and lithium-containing aluminum silicate glasses. Now, specific reference will be made to low-viscosity glasses and lithium-containing aluminum silicate glasses according to various embodiments. Now, specific reference will also be made to low-viscosity lithium-containing aluminum silicate glasses containing fusion lines.

[0053] Glass manufacturing system

[0054] Embodiments of the methods and apparatus for forming glass ribbons will now be described in detail, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals are used in all the drawings to denote the same or similar parts. Figure 1One embodiment of an apparatus for manufacturing a glass ribbon is shown and generally designated by reference numeral 10 throughout this document. According to one embodiment, an apparatus for forming a glass ribbon includes a forming wedge disposed in an enclosure and comprising a pair of downwardly sloped forming surface portions converging at a root. A plurality of heating cylinders can be disposed in a port of the enclosure. Each heating cylinder can include a heat directing surface oriented at an angle greater than about 90° relative to a bottom surface of the heating cylinder. The heat directing surface can include a heating element disposed adjacent the heat directing surface. The heating cylinders can be disposed such that the heat directing surfaces face the forming wedge, and an upper edge of the heat directing surface and a top surface of the heating cylinder are positioned higher than at least one of the root of the forming wedge or a trough of the forming wedge, thereby directing heat from the heat directing surface of the heating cylinder toward the root of the forming wedge or the trough of the forming wedge. Various embodiments of methods and apparatuses for forming a glass ribbon will be described in greater detail below with specific reference to the drawings.

[0055] Throughout this document, ranges can be presented as from "about" one particular value and / or to "about" another particular value. When such a range is recited, another embodiment includes from the one particular value and / or to the other particular value. Similarly, where the prefix "about" is used to indicate that a numerical value is an approximation, it is understood that the specific numerical value forms another embodiment. It is also understood that the end points of each range, both inclusive and exclusive, are meaningful.

[0056] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and not intended to imply absolute orientation.

[0057] Unless otherwise stated, no aspect of any method described herein is intended to require its steps to be performed in a particular order, nor is it intended to require any particular orientation of apparatus. Thus, when a method claim recites steps as being performed in any particular order, or any apparatus claim recites components as being arranged in any particular order or orientation, or any claim recites steps or components in any other way that implies a particular order or orientation, such an embodiment is merely an example of one way to implement the claim and is not intended to imply that the claim requires that the steps be performed in that order, or that the components be arranged in that order or orientation, or that the steps or components be executed in any way that is not expressly dictated by the claim. The same applies to any possible implicit recitations of any of the claims that refer to a specific claim or claims by area of disclosure in connection with a sequence of actions, blocks, components, states, steps or

[0058] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects with two or more such components, unless the context clearly indicates otherwise.

[0059] Referring now to Figure 1 , one embodiment of a glass forming apparatus 10 for forming a glass ribbon 12 is schematically shown. The glass forming apparatus 10 generally includes a melting vessel 15 configured to receive a glass batch material 16 from a batch hopper 18. The glass batch material 16 can be introduced to the melting vessel 15 by a batch delivery device 20 driven by a motor 22. An optional controller 24 can be provided to activate the motor 22, and a molten glass level probe 28 can be used to measure the level of the glass melt within a standpipe 30 and transmit the measured information to the controller 24.

[0060] The glass forming apparatus 10 includes a fining vessel 38 (e.g., a fining tube) downstream of the melting vessel 15 and connected to the melting vessel 15 by way of a first connecting tube 36. A mixing vessel 42 (e.g., a stir chamber) is downstream of the fining vessel 38. A delivery vessel 46 (e.g., a bowl) can be downstream of the mixing vessel 42. As shown, a second connecting tube 40 connects the fining vessel 38 and the mixing vessel 42, and a third connecting tube 44 connects the mixing vessel 42 and the delivery vessel 46. As further shown, a downcomer 48 can be positioned to deliver the glass melt from the delivery vessel 46 to an inlet 50 of a forming vessel 60.

[0061] The melting vessel 15 is generally fabricated from refractory material (e.g., refractory brick (e.g., ceramic brick)). The glass forming apparatus 10 can also include components that are generally constructed from platinum or platinum-containing metals, such as platinum-rhodium, platinum-iridium, and combinations thereof, although these components can also include refractory metals such as molybdenum, palladium, rhenium, tantalum, titanium, tungsten, ruthenium, osmium, zirconium, and alloys and / or zirconium dioxide thereof. The platinum-containing components can include one or more of the first connecting tube 36, the fining vessel 38, the second connecting tube 40, the standpipe 30, the mixing vessel 42, the third connecting tube 44, the delivery vessel 46, the downcomer 48, and the inlet 50. The forming vessel 60 can also be fabricated from refractory material (e.g., refractory brick and / or refractory metal) and is designed to form the glass melt into the glass ribbon 12.

[0062] Figure 2 is a cross-sectional perspective view of the glass forming apparatus 10 along Figure 1 line 2-2. As noted, the forming vessel 60 includes a forming wedge 62 that includes a trough 61 that opens upward (i.e., in the +x direction of the coordinate axes shown), a pair of downwardly sloped (i.e., in the -z direction of the coordinate axes shown) walls 63, and a pair of upwardly sloped (i.e., in the +z direction of the coordinate axes shown) walls 64. Figure 2 Figure 2 ​The forming surface portions 66a and 66b (in the -x direction of the coordinate axis shown) extend between opposite ends 64a and 64b of the forming wedge 62. The downwardly sloping forming surface portions 66a and 66b converge along a downstream direction 68 to form a root 70. A drawing plane 72 extends through the root 70. The glass strip 12 can be drawn from the forming wedge 62 along the drawing plane 72 in the downstream direction 68, as further described below. As shown, the drawing plane 72 is in a generally horizontal longitudinal direction (through the root 70) of the forming container 60. Figure 2 The coordinate axes shown (+ / -y directions) divide the root 70 in two. However, it should be understood that the drawing plane 72 can extend relative to the root 70 in various orientations other than dividing the formed container 60 through the root. Although Figure 1 and Figure 2 One embodiment of the glass forming apparatus and forming container is shown in general, but it should also be understood that aspects of this disclosure can be used in various other forming container constructions.

[0063] See Figure 1 and 2 In some embodiments, the forming container 60 may include edge guides 80a, 80b that intersect with the pair of downwardly sloping forming surface portions 66a, 66b. By guiding the molten glass close to the root 70 of the forming container 60, the edge guides help achieve the desired glass ribbon width and edge characteristics. In other embodiments, the edge guides may intersect with both downwardly sloping forming surface portions 66a, 66b. As a supplement or alternative, in some embodiments, the edge guides may be positioned at opposite ends 64a, 64b of the forming wedge 62, respectively. For example, as... Figure 1 As shown, edge guides 80a and 80b can be positioned at opposite ends 64a and 64b of the forming wedge 62, respectively, and the edge guides 80a and 80b can be configured to intersect with both downwardly inclined forming surface portions 66a and 66b. As further shown, each edge guide 80a and 80b is substantially identical to the others. However, it should be understood that in alternative embodiments, the edge guides can have different constructions and / or geometries depending on the specific characteristics of the glass forming apparatus. Furthermore, it should be understood that various forming wedge and edge guide constructions can be used according to aspects of this disclosure. For example, aspects of this disclosure can be used in configurations of shaped wedges and edge guides disclosed in U.S. Patent Nos. 3,451,798, 3,537,834, 7,409,839, U.S. Patent Application No. 14 / 278582, filed May 15, 2014, and / or U.S. Provisional Patent Application No. 61 / 155,669, filed February 26, 2009, the entire contents of which are incorporated herein by reference.

[0064] See stillFigure 1 The glass forming apparatus 10 can optionally include (not shown) at least one edge roll assembly for drawing the glass ribbon from the root 70 of the forming vessel 60. It should be appreciated that various edge roll assembly configurations can be used in accordance with aspects of the disclosure, as further described below.

[0065] The housing 14 encloses the forming vessel 60. The housing 14 can be formed of steel and can contain refractory and / or insulating properties to insulate the forming vessel 60 and the molten glass flowing in and around the forming vessel 60 from the ambient environment. Although not shown, the housing 14 can include a plurality of cooling tubes or bayonets that can extract energy from the forming vessel 60 portions with water or other heat transfer medium (e.g., air, etc.). Such cooling tubes or bayonets located at higher elevations in the housing 14 (e.g., above or proximate to the weir of the forming vessel 60 or proximate to the forming surface of the forming vessel 60) can more rapidly increase the viscosity to improve glass stiffness and baggy warp resistance. Further, for the same glass ribbon thickness, one or more pairs of such cooling tubes or bayonets at these higher elevations can achieve lower root viscosities.

[0066] Referring now to Figures 1-2 In operation, batch material (specifically, batch material for forming glass) is fed from the batch hopper 18 into the melting vessel 15 with the batch delivery device 20. In the melting vessel 15, the batch material 16 is melted into molten glass. The molten glass passes from the melting vessel 15 through the first connecting tube 36 into the fining vessel 38. In the fining vessel 38, dissolved gases that can cause defects in the glass are removed from the molten glass. The molten glass then passes from the fining vessel 38 through the second connecting tube 40 into the mixing vessel 42. The mixing vessel 42 homogenizes the molten glass (e.g., by agitation), and the homogenized molten glass passes through the third connecting tube 44 to the delivery vessel 46. The delivery vessel 46 discharges the homogenized molten glass through the downcomer 48 and into the inlet 50, from which the homogenized molten glass passes into the trough 61 of the forming vessel 60.

[0067] As the molten glass 17 fills the upwardly opening trough 61 of the forming wedge 62, it overflows the trough 61 and flows over the inclined forming surface portions 66a, 66b, and re-converges at the root 70 of the forming wedge 62 to form the glass ribbon 12. As shown in Figure 2 The glass ribbon 12 can be drawn in the downstream direction 68 along a draw plane 72 that extends through the root 70.

[0068] For example, as shown in Figures 1-2The illustrated glass forming apparatus has found that evolving technologies such as high performance displays (HPD) or cover glass displays employing organic light emitting diode (OLED) technology benefit from glass compositions that are difficult to form (e.g., glass compositions having a lower liquidus viscosity and / or lithium aluminosilicate containing glasses). Such glass compositions are typically manufactured at higher forming temperatures to prevent defects such as devitrification from forming in the glass ribbon drawn from the forming vessel 60. The glass forming apparatus described herein can also employ heating cylinders positioned proximate the root of the forming vessel 60 to maintain the higher temperature of the molten glass in the glass ribbon 12 drawn from the root 70 of the forming vessel 60 to facilitate the sheet forming process and prevent defects from forming in the glass ribbon.

[0069] In particular, referring again to Figures 1-3 , to maintain the higher temperature of the molten glass in the glass ribbon 12 drawn from the root 70 of the forming vessel 60, the glass forming apparatus 10 further includes a plurality of heating cylinders 110, 111 positioned in a series of ports 112 formed in the housing 14 and / or a housing seal plate 136 Figure 3 ) that forms a component of the housing 14 Figures 1-2 . As shown in Figure 3 , the first series of ports 112 and the second series of ports (not shown) are arranged such that the first plurality of heating cylinders 110 and the second plurality of heating cylinders 111 are positioned on opposite sides of the root 70 such that the draw plane 72 extends between the first plurality of heating cylinders 110 and the second plurality of heating cylinders 111. The first plurality of heating cylinders 110 and the first series of ports 112 will be described in greater detail below. However, it should be understood that the first plurality of heating cylinders 110 and the second plurality of heating cylinders 111 are substantially identical to one another or are similarly configured. Similarly, it should be understood that each series of ports 112 are substantially identical to one another or are similarly configured.

[0070] As shown in Figures 1-2 , the first series of ports 112 are arrayed across the width of the forming vessel 60 Figure 1 and the + / - y direction of the coordinate axes shown in 2 ) such that the first series of ports 112 span the width of the draw plane 72 Figure 1 and the + / - y direction of the coordinate axes shown in 2 ) over which the glass ribbon 12 is drawn. Thus, it should be understood that the first plurality of heating cylinders 110 (when inserted into the corresponding ports) are also arrayed across the width of the forming vessel 60 and extend across the width of the draw plane 72 of the glass ribbon 12. In some embodiments, each of the ports of the first series of ports 112 are laterally (i.e., Figure 1 and2 The ports are spaced apart in the + / -y direction of the coordinates shown. In some embodiments, each port of the first series of ports 112 may be laterally spaced apart from each other at equal distances.

[0071] The first group of multiple heating cylinders 110 can be configured to direct heat to the root 70, thereby maintaining the root 70 at a desired temperature, for example, above the devitrification temperature of the molten glass, and thus mitigating the formation of defects in the glass. Figure 2 and 3 As shown, the first series of ports 112 can be located within the housing 14, so that in the -z direction, the first group of multiple heating cylinders 110 are adjacent to and spaced apart from the root 70 of the forming container 60. Figure 3 In the illustrated embodiment, the first group of multiple heating cylinders 110 are spaced apart from the root 70 in the -z direction, and are further arranged such that a portion of each heating cylinder 110 is above the root 70 (in the +x direction of the coordinate axis) and a portion is below the root 70 (in the -x direction of the coordinate axis). Alternatively, in Figure 1 In the illustrated embodiment, the first series of ports 112 may be located within the housing 14 such that the first group of multiple heating cylinders 110 are positioned completely above the root 70. In other embodiments (not shown), the first series of ports 112 may be located within the housing 14 such that the first group of multiple heating cylinders 110 are positioned below the root 70.

[0072] Figures 1-3 The first group of multiple heating cylinders 110 is shown, which includes five heating cylinders 110a, 110b, 110c, 110d, and 110e. Therefore, Figures 1-3 The positions of these five heating cylinders are shown in the first series of ports 112, including five ports 112a, 112b, 112c, 112d, and 112e, formed within the housing 14. However, it should be understood that this is an exemplary number, and the number of heating cylinders in the first group of multiple heating cylinders 110 and the corresponding number of ports in the first series of ports 112 may be greater than or less than 5. Similarly, the width of the heating cylinders depends on the number of heating cylinders used and the width of the forming container. For example, Figure 1 Five heating cylinders are shown across the entire width of the forming container, while Figure 1 Five heating cylinders are shown, covering a width less than the entire width of the forming container. One of the first group of multiple heating cylinders 110 will be described in more detail herein. However, it should be understood that each heating cylinder 110a, 110b, 110c, 110d, 110e in the first group of multiple heating cylinders 110 and each heating cylinder in the second group of multiple heating cylinders 111 are substantially the same or similar in construction.

[0073] See nowFigures 3-5 In embodiments, each of the first plurality of heating cylinders 110 includes a jacket 120 having a heat directing surface 122 with at least one heating element 124 disposed on or adjacent to a face thereof. The jacket 120 can be fabricated from a variety of materials suitable for use in the elevated temperature conditions associated with the glass forming apparatus 10. For example, the jacket 120 (and other portions of the heating cylinder 110a) can be formed from a refractory material, such as a high temperature nickel-based alloy, steel (e.g., stainless steel), or other alloy or material (or combination of materials) to meet the structural and / or thermal parameters associated with the glass forming apparatus 10. For example, in one embodiment, the jacket 120 can be fabricated from a nickel-based alloy (e.g., Haynes® 214® nickel-based alloy produced by Haynes International, Inc).

[0074] While Figures 3-5 While the heating cylinder 110a is shown as including a jacket, it is understood that other embodiments are contemplated and are possible. For example, instead of including a separate jacket 120, the heat directing surface 122 can be fixed with a block of refractory material (or multiple blocks of refractory material) rather than having a separate jacket formed from a metal / alloy. For example, in some embodiments, the heat directing surface is fixed with a body formed from a NA-33 refractory block produced by ANH refractories, but is not limited thereto.

[0075] In one embodiment, the heat directing surface 122 of the heating cylinder 110a is formed from a ceramic refractory support material having a low emissivity. Suitable ceramic refractory materials include, but are not limited to, SALI plates available from Zircar Ceramics. Portions of the heating cylinder 110a that are not directly exposed to the high temperatures of the glass forming apparatus 10 can be fabricated from materials suitable for lower temperature applications. For example, when the heating cylinder 110a includes a jacket, the back face 125 of the jacket 120 can be fabricated from stainless steel selected to meet the structural and / or thermal parameters associated with the glass forming apparatus 10, such as 420 stainless steel.

[0076] In the embodiments described herein, the heat-directing surface 122 of the heating cylinder 110a is oriented at an angle a relative to the bottom surface 126 of the heating cylinder 110a. In the embodiments described herein, the angle a is greater than 90°. For example, in certain embodiments, the angle a of the heat-directing surface 122 relative to the bottom surface 126 of the heating cylinder 110a can be from about 120° to about 150°. In other embodiments, the angle a of the heat-directing surface 122 relative to the bottom surface 126 of the heating cylinder 110a can be from about 130° to about 140°. In particular embodiments, the angle a of the heat-directing surface 122 relative to the bottom surface 126 of the heating cylinder 110a can be about 135°.

[0077] In some embodiments, the downward-facing orientation of the heat-directing surface 122 facilitates placement of the heating cylinder 110a in the housing 14 of the glass forming apparatus 10 such that the heat-directing surface 122 of each replaceable heating cylinder faces the root 70 of the forming vessel 60. In particular, the downward-facing orientation of the heat-directing surface 122 enables the heat-directing surface 122 to radiate and direct heat toward and onto the root 70 of the forming vessel 60 with only minimal heat loss to the surrounding environment, particularly the area above the root 70, e.g., above the heating cylinder.

[0078] Referring again to Figures 1-3 In some embodiments, the heating cylinder 110a is placed in the housing 14 of the glass forming apparatus 10 such that the upper edge 123 of the heat-directing surface 122 and the top surface 127 of each heating cylinder 110a is positioned above the root 70. This positioning enables the heat-directing surface 122 of the heating cylinder 110a to direct heat toward and onto the root 70 of the forming vessel 60, thereby increasing the temperature of the root 70 and the temperature of the molten glass flowing through the forming vessel 60 in the area of the root 70. For example, as shown in FIG. 1, the heating cylinder 110a can be positioned entirely upstream of the root 70. In alternative embodiments, as shown in FIG. 2, the heating cylinder 110a can be positioned partially upstream of the root 70 and partially downstream of the root 70. Figure 1 Figure 3 ​As shown, the position of the heating cylinder 110a can be partially upstream of the root 70. For example, the top surface 127 of the heating cylinder 110a can be positioned upstream of the root 70, while the bottom surface 126 of the heating cylinder 110a can be positioned downstream of the root 70. Positioning the heating cylinder 110a partially upstream of the root 70 can provide sufficient heating of the root 70 to prevent devitrification of the molten glass while reducing heat loss above the non-target region of the root 70 due to the angled heat-conducting surface of the heating cylinder. In addition, positioning the heating cylinder 110a partially upstream of the root 70 can achieve a closer position of the heating cylinder (and in particular, the heat-directing surface 122) to the root 70, so that more heat is incident on the root 70 and the molten glass flowing over the root 70.

[0079] More specifically, the angle of the heat-directing surface 122 and the position of the heating cylinder 110a in the housing 14 is such that objects positioned below the top surface 127 of the heating cylinder 110a (e.g., the root 70 of the forming vessel 60) have a greater view factor from the heat-directing surface than objects positioned above the top surface 127 of the heating cylinder 110a. As used herein, the term "view factor" refers to the relative proportion of thermal radiation from the heat-directing surface 122 that is incident on a particular surface. For example, because objects positioned below the top surface 127 of the heating cylinder 110a (e.g., the root 70 of the forming vessel 60) have a greater view factor from the heat-directing surface 122 than objects positioned above the top surface 127 of the heating cylinder 110a, the objects positioned below the top surface 127 of the heating cylinder 110a receive a greater heat flux from the heat-directing surface 122 of the heating cylinder 110a than the objects positioned above the top surface 127 of the heating cylinder 110a.

[0080] In some other embodiments (not shown), the position of the heating cylinder 110a can be downstream of the root 70 (i.e., in the -x direction). In these embodiments, the angle of the heat-conducting surface of the heating cylinder can be such that heat is directed toward the root 70, as heat rises along the angled heat-conducting surface.

[0081] In the embodiments described herein, it is to be understood that the heating cylinder 110a can function as both a heater to heat the root 70 and as a heat shield that thermally isolates and shields regions above the heating cylinder 110a from regions below the heating cylinder 110a, thereby preventing heat loss from the root 70 and the molten glass flowing through the root 70 to non-target regions located above the root 70 of the forming vessel 60. Specifically, as described above, the heat directing surface 122 of the heating cylinder 110a is oriented at an angle a greater than 90° relative to the bottom surface 126 of the heating cylinder 110a. As such, the top surface 127 of the heating cylinder 110a and the upper edge 123 of the heat directing surface 122 can cantilever over the lower edge 129 and the bottom surface 126 of the heating cylinder 110a. This arrangement of the heat directing surface 122 creates the view factor of the heating cylinder as described above. In addition, the cantilevered arrangement of the heat directing surface 122 allows the heat directing surface 122 to extend over the gap 170 between the heat directing surface 122 and the forming vessel 60, reducing the distance between the forming vessel 60 and the heating cylinder, and slowing the loss of heat from regions downstream of the root to regions of the glass forming apparatus 10 located upstream of the root 70 of the forming vessel 60. As such, the heating cylinder 110a also thermally shields the regions above the heat directing surface 122 from the regions below the heat directing surface 122.

[0082] Still referring to FIGS. 4-5, the heating element 124 located on or adjacent to the heat directing surface 122 is a resistive heating element. In certain embodiments, the material of the resistive heating element can be molybdenum disilicide. In some embodiments, the heating element 124 can be constructed from a wire formed of molybdenum disilicide. For example, in one embodiment, the heating element 124 can be constructed from a molybdenum disilicide wire that is located in a serpentine shape on the heat directing surface 122, but is not limited thereto. For example, the heating element 124 formed of molybdenum disilicide can include a winding element located on the heat directing surface 122, but is not limited thereto. The diameter of the end of the heating element 124 extending through the heating cylinder 110a can be selected to minimize energy loss from the heat directing surface 122.

[0083] It has been determined that forming a heating cylinder as described herein can greatly improve the heating efficiency of the heating cylinder. This can be attributed to the increased power carrying capacity of the molybdenum disilicide heating element as compared to other materials, as well as the additional refractory insulation and angled heat directing surface. In addition, it has also been found that the combination of a segmented heating cylinder (e.g., the heating cylinder described herein) with a molybdenum disilicide heating element achieves a higher forming temperature at the root 70 as compared to other conventional heating element materials. This enables, for example, the use of a higher forming temperature, which in turn prevents devitrification of the molten glass and mitigates defects in the glass ribbon drawn from the root 70 of the forming vessel 60. In addition to this, the molybdenum disilicide heating element advantageously achieves such forming temperatures at a lower power input as compared to the use of conventional heating element materials, since the forming temperature at the root 70 is equal.

[0084] While Figure 4A While a single heating element 124 is shown positioned on the heat directing surface 122 of the heating cylinder 110a, it should be understood that other configurations are also contemplated and are possible. For example, in some embodiments, the heating element 124 can be a segmented heating element, which includes two or more separate heating elements, each powered and controlled separately. This enables the formation of the heat directing surface 122 of the heating cylinder 110a in separate heating zones, which can be independently controlled, thereby providing more fine control of the temperature profile of the heat directing surface 122.

[0085] Still referring to FIGS. 4-5, located behind the heat directing surface 122 is one or more blocks of refractory material 128 that isolate the heat directing surface 122 from the rest of the heating cylinder 110a. These blocks of refractory material 128 can be located within the outer shell 120 (as shown in FIGS. 4 and 5) or can be attached directly to the heat directing surface 122 without an outer shell. In some embodiments, the refractory material 128 is oriented such that heat transfer from the heat directing surface 122 is minimized. Specifically, in some embodiments, the refractory material 128 is oriented in alternating longitudinal and horizontal stacks as it is believed that alternating longitudinal and horizontal stacks of refractory material 128 can help reduce heat at the seams between the blocks. In some embodiments, the refractory material 128 can be oriented at an angle approximately equal to the angle of the heat directing surface 122. In other embodiments, for example, when the heat directing surface 122 is formed from a refractory material such as a SALI board, the refractory material of the heat directing surface 122 can extend into the outer shell. In the embodiments described herein, the refractory material 128 can be commercially available refractory materials including, but not limited to: SALI boards, Insulating Fire Brick (IFB), DuraBoard® 3000, and / or DuraBoard® 2600. In some embodiments, the refractory blocks can have a first layer closest to the heat directing surface 122 formed from a SALI board and a second layer located behind the first layer formed from an IFB.

[0086] Various attachment structures can be used to mount the heating cylinders 110a relative to the root 70. In some embodiments, the heating cylinders 110a can be mounted to brackets 114 that engage the housing 14 and / or the housing seal plate 136, as shown in FIG. 6. Additionally or alternatively, the heating cylinders 110a can be placed on T-wall support brackets 116 that are attached to the housing 14 and / or the housing seal plate 136, as shown in FIG. 7. In some embodiments, each heating cylinder is removably mounted into a port of the housing 14 of the glass forming apparatus 10. Each individual heating cylinder can be independently controlled such that the use of the plurality of heating cylinders can achieve a desired temperature profile on the root of the forming wedge. Further, the separate nature of each heating cylinder minimizes the impact of failed heating elements and / or replacement of heating cylinders. That is, in a single heating element failure event during operation, the failure of that heating element only results in a partial loss of overall heating. Further, because the heating cylinders are separately controlled, adjacent heating cylinders can be individually adjusted to make up for the loss of heating from the failed heating element. Further, the modular nature of the heating cylinders means that replacement of a single cylinder only impacts a portion of the overall heating provided, thereby reducing production losses. Figure 3 Figure 2

[0087] ​​In certain embodiments, the apparatus can further include a controller 180 configured to control heating associated with the plurality of heating cylinders 110, 111. In certain embodiments, the controller 180 can be operably connected to each of the plurality of heating cylinders 110, 111, as shown in Figure 1 In certain embodiments, control of individual ones of the plurality of heating cylinders 110, 111 can be segmented. As used herein, the term "segmented" refers to the ability to independently control and adjust the temperature of each individual heating cylinder, thereby providing controlled control of the temperature of the glass ribbon during manufacture. The controller can include a processor and a memory (storing computer readable and executable instructions) that, when executed by the processor, independently adjust the power of each heating cylinder, thereby independently increasing or decreasing the amount of heat provided by each heating cylinder based on temperature feedback or other process parameters. Thus, the controller 180 can be used to adjust the power provided to each of the plurality of heating cylinders 110, 111 in different ways across the width of the root 70 and the width of the draw plane 72 of the glass ribbon 12.

[0088] In certain embodiments, the controller 180 can be configured to independently operate each of the plurality of heating cylinders 110, 111 based on thermal feedback from the glass forming apparatus. For example, in one embodiment, the controller 180 is configured to obtain thermal feedback from a thermal sensor 182, as shown in Figure 1 The feedback obtained by the thermal sensor can be used by the controller 180 to individually adjust each of the plurality of heating cylinders 110, 111 to provide controlled control of the thermal characteristics of the apparatus as the glass ribbon is manufactured. The thermal characteristics can include, for example, temperature and / or heat loss associated with a portion of the glass forming apparatus, such as the heat directing surface 122 of each of the plurality of heating cylinders 110, 111, a portion of the edge guides 80a, 80b, a portion of the end of the forming vessel 60, a portion of the molten glass, and / or other features of the glass forming apparatus 10.

[0089] In one embodiment, the thermal sensor 182 can detect a temperature that is above a target level, and the controller 180 can cause the power of at least one of the plurality of heating cylinders 110, 111 to be decreased so that less heat is transferred to the target area, thereby decreasing the temperature until the target level of temperature is obtained. Alternatively, in certain embodiments, the thermal sensor 182 can detect a temperature that is below a target level, where the controller 180 can cause the power of at least one of the plurality of heating cylinders 110, 111 to be increased so that more heat is transferred to the target area, thereby increasing the temperature until the target level of temperature is obtained.

[0090] As described above and in additional embodiments, one or more heating cylinders or similar devices may be provided near the edge guides 80a, 80b or portions thereof and a portion of the end of the forming container 60. For example, see [link to example]. Figure 27 and 28 The first end of the forming container 60 may provide a first edge guide 80a. Similarly, the opposite second end of the forming container 60 (not shown) may include a second edge guide 80b, which in some embodiments may be a mirror image of the first edge guide 80a. See also Figure 27 In describing the first edge guide 80a, it will be understood that such description can also be applied similarly or identically to the second edge guide 80b. In fact, in some embodiments, the second edge guide 80b may correspond to the first edge guide 80a. In some embodiments, at least a portion of the molding container 60 or the entire molding container 60 may be enclosed within the housing 14 (see, for example...). Figure 1 The housing 14 is designed to help maintain the desired atmospheric conditions. For example, in some embodiments, the housing 14 may be designed to maintain the atmospheric temperature within a desired temperature range. In some embodiments, such as Figure 28 As schematically shown by the hidden lines, the housing 14 may have opposing lower doors 142a, 142b that define an opening 202 below the root 70 through which the glass strip 12 is drawn. The width of the opening 202 may be small enough to reduce heat loss through the opening, but also large enough to prevent interference with the glass strip 12 drawn through the opening 202.

[0091] In some embodiments, the first edge guide 80a and the second edge guide 80b intersect at least one of the pair of downwardly sloping surface portions 66a, 66b, respectively. Indeed, as shown, the first outwardly facing contact surface 217a of the first upper portion 215a of the first edge guide 80a may intersect with the first downwardly sloping surface portion 66a of the first edge guide 80a, and the second outwardly facing contact surface 217b of the second upper portion 215b of the second edge guide 80b may intersect with the second downwardly sloping surface portion 66b of the second edge guide 80b. Embodiments described herein may include a heating surface comprising a heat footprint facing the adjacent edge guide surface. Figure 27 and 28As shown, a pair of heating faces can optionally be provided for one or both edge guides 80a, 80b. For example, the first edge guide 80a can be provided with a first heating face 225a and a second heating face 225b, with the understanding that in some embodiments the second edge guide 80b can similarly be provided with similar or identical first and second heating faces. While each edge guide can provide a single heating face, providing first and second heating faces as shown can enable heating of outer contact surfaces that oppose one another and contact corresponding portions of the converging stream of molten material upstream (e.g., immediately upstream of the edges of the stream that are fused together as they are drawn away from the inner surfaces 222 of the edge guides) of the stream of molten material.

[0092] As shown, in some embodiments the second heating face 225b can be a mirror image of the first heating face 225a about the draw plane 72 of the glass ribbon. For example, in some embodiments the second heating face 225b can be a perfect mirror image of the first heating face 225a, although in other embodiments different configurations can be provided. As such, the first heating face 225a and the corresponding thermal footprint 227a associated with the first outward-facing contact surface 221a of the first edge guide 80a will be described, with the understanding that such features and orientations can be similarly or identically applicable to the second heating face 225b and the corresponding thermal footprint 227b associated with the second outward-facing contact surface 221b of the first edge guide 80a. Further, in some embodiments the first heating face (not shown) and / or the second heating face (not shown) associated with the second edge guide 80b can be mirror images of the first and second heating faces 225a, 225b associated with the first edge guide 80a.

[0093] In some embodiments, the first thermal footprint 227a of the first heating face 225a can face at least toward the first outward-facing contact surface 221a of the lower portion 219 of the first edge guide 80a. A projection 228a of the first thermal footprint 227a in a first resultant direction 229a of the first heating face 225a within the first thermal footprint 227a can intersect the first outward-facing contact surface 221a of the first edge guide 80a, shown as a hatched contact area 403a.

[0094] As further shown in the figures, the second thermal footprint 227b of the second heating face 225b can face at least toward the second outward-facing contact surface 221b of the lower portion 219 of the first edge guide 211a. A projection 228b of the second thermal footprint 227b in a second resultant direction 229b of the second heating face 225b within the second thermal footprint 227b can intersect the second outward-facing contact surface 221b of the first edge guide 211a, shown as a hatched contact area 403b.

[0095] Reference will be made to Figure 27 With respect to the first synthesis direction 229a associated with the first heating face 225a, it is to be understood that other synthesis directions of the present disclosure can have similar or identical features as the first synthesis direction 229a. The synthesis direction is considered to be the effective direction of all directions normal (i.e., perpendicular) to the surface of the heating face within the thermal footprint. For example, Figure 27 The first heating face 225a within the thermal footprint 227a is a flat planar surface. Thus, the synthesis direction is the direction normal to the flat planar surface. However, in some embodiments, the heating face within the thermal footprint need not be flat. For example, the heating face within the thermal footprint can also include a concave surface, and in such embodiments, the synthesis direction would be considered to be the sum of all normal direction vectors (i.e., tangents or normals at the surface) at each point on the heating face within the thermal footprint. Similarly, the heating face within the respective thermal footprint can also include a convex surface. In such embodiments, the synthesis direction would be considered to be the sum of all normal direction vectors (i.e., tangents or normals at the surface) at each point on the heating face within the thermal footprint.

[0096] Providing heating faces 225a, 225b with different shapes can help the heating faces more closely face the contact surfaces of the edge guides 80a, 80b to be heated. In some embodiments, the distance between all portions of the heating face within the thermal footprint can be approximately the same distance or within a certain distance range with respect to the corresponding contact surface of the edge guide. As such, all portions of the thermal footprint can effectively face the corresponding portions of the contact surface in the synthesis direction to minimize the distance and thereby maximize the radiative heat transfer between the heating face and the contact surface of the edge guide. An exemplary heating face can be provided with a heating element (e.g., a heating coil designed to provide radiative heating). The heating coil can be placed on the heating face such that the outer perimeter of the heating coil defines the thermal footprint. The radiative heat projection in the synthesis direction from the heating element can intersect the facing contact surface of the edge guide. In other embodiments, the heating face can include a heating plate or other heating element such that the outer perimeter of the heating plate or heating element defines the thermal footprint of the heating face. For example, the heating plate can be heated on the hidden side by a torch, and the heat transfer through the plate and the radiation from the facing surface of the plate intersects the contact surface of the edge guide. Such a configuration can avoid exposing the molten material to a heating gas flow, which can interfere with the flow of the molten material on the contact surface. The above-described and as shown in Figure 27 and 28 Such directed radiative heating of the surface of the edge guide in contact with the molten material can reduce undesirable attenuation of the width of the low viscosity glass ribbon by reducing the unnecessary application of heat to other portions of the molten material and / or the edge of the glass ribbon being drawn from the root of the forming vessel.

[0097] Referring again to Figure 2 Generally, more heat is lost to the ambient environment on the two outer ends of the draw plane 72 of the glass ribbon 12 (the widthwise direction of the forming vessel, i.e., + / - y direction) than the middle portion of the draw plane 72. As such, the power and heat provided by the controller 180 to the heating cylinders 110, 111 located near the edges of the draw plane 72 of the glass ribbon 12 can be greater than the heating cylinders located in the middle of the draw plane 72 to both compensate for the heat loss in these areas and to account for the greater thickness of the glass near the edges of the draw plane 72.

[0098] In certain embodiments, the controller can be configured to independently operate each of the plurality of heating cylinders 110, 111 based on thermal feedback from the glass forming apparatus 10. For example, in one embodiment, the controller is configured to obtain thermal feedback from at least one thermal sensor (not shown) located near the root 70 of the forming vessel 60. The feedback obtained by the at least one thermal sensor can be used by the controller to individually adjust each of the plurality of heating cylinders 110, 111 to provide controlled control of the thermal characteristics of the apparatus as the glass ribbon is being manufactured. The thermal characteristics can include, for example, temperatures and / or heat losses associated with a portion of the glass forming apparatus 10, such as the heat directing surface 122 of a heating cylinder 110a; the root 70; an end portion of the forming vessel 60; a portion of the molten glass; and / or other features of the glass forming apparatus 10.

[0099] In one embodiment, the at least one thermal sensor can detect a temperature that is above a target level, and the controller can individually cause the power of at least one of the plurality of heating cylinders 110, 111 to be decreased so that less heat is transferred to the target area, thereby decreasing the temperature until the target level of temperature is obtained. Alternatively, in certain embodiments, the at least one thermal sensor can detect a temperature that is below a target level, where the controller can individually cause the power of at least one of the plurality of heating cylinders 110, 111 to be increased so that more heat is transferred to the target area, thereby increasing the temperature until the target level of temperature is obtained.

[0100] While Figures 1-3 One embodiment of the glass forming apparatus 10 is schematically shown, where the heating cylinders 110a-110e are positioned near the root 70 of the forming wedge 62, it should be understood that other embodiments are contemplated and are possible. Referring to Figures 4A-4B, 5, 7, and 8, for example, in one embodiment, the plurality of heating cartridges can be positioned proximate to the trough 61 of the forming vessel 60. In particular, the forming vessel 60 is positioned within a housing (not shown) and can include a trough 61 for receiving molten glass and a pair of downwardly sloped forming surface portions 66a, 66b converging at a root 70, as described above. The plurality of heating cartridges 110a-110e can be removably positioned in ports formed in the housing, as described above, such that the heat directing surface 122 of each heating cartridge faces the forming vessel 60 and the upper edge 123 of the heat directing surface 122 and the top surface 127 of the heating cartridge are positioned above the trough 61 of the forming vessel 60 to direct heat from the heat directing surface 122 of the heating cartridge toward the trough 61 of the forming vessel 60 to heat the glass positioned at the top of the weir 63 of the trough 61 of the forming vessel 60 and prevent devitrification.

[0101] More particularly, in these embodiments, each heating cartridge can have substantially the same structure as shown and described herein with respect to Figures 4A-4B and 5. In these embodiments, the angle a of the heat directing surface 122 of the heating cartridge 110a relative to the bottom surface 126 of the heating cartridge 110a can also be greater than or equal to 90°. For example, in certain embodiments, the angle a of the heat directing surface 122 relative to the bottom surface 126 of the heating cartridge 110a can be from about 120° to about 150°. In other embodiments, the angle a of the heat directing surface 122 relative to the bottom surface 126 of the heating cartridge 110a can be from about 130° to about 140°. In particular embodiments, the angle a of the heat directing surface 122 relative to the bottom surface 126 of the heating cartridge 110a can be about 135°.

[0102] In some embodiments, the elevation of the heating cartridges 110a-110e relative to the forming vessel 60 can be such that the lower edge 129 of the heat directing surface and the bottom surface 126 of the heating cartridge are positioned below the top of the weir 63. In these embodiments, the angle a of the heat directing surface 122 of the heating cartridge 110a relative to the bottom surface 126 of the heating cartridge 110a can be greater than or equal to 90° such that heat from the heating cartridge is directed toward the trough 61 of the forming vessel 60. In some other embodiments, the elevation of the heating cartridges 110a-110e relative to the forming vessel 60 can be such that the lower edge 129 of the heat directing surface and the bottom surface 126 of the heating cartridge are positioned above the trough 61. In these embodiments, the angle a of the heat directing surface 122 of the heating cartridge 110a relative to the bottom surface 126 of the heating cartridge 110a can be greater than 90° such that heat from the heating cartridge is directed downward toward the trough 61 of the forming vessel 60.

[0103] In some embodiments, the heating cartridges 110a-110e can be arranged across the width of the forming vessel 60, as shown in Figure 7 In some embodiments, each of the plurality of heating cartridges 110a-110e is positioned at substantially the same elevation in the + / - x direction. However, in some embodiments, the plurality of heating cartridges 110a-110e can be arranged in a stepped configuration, as shown in Figure 9 When the weir 63 or sidewall of the trough 61 has an angled configuration, such a configuration of heating cartridges can be used, as shown in Figure 9

[0104] In embodiments where the plurality of heating cartridges 110a-110e are positioned proximate to the trough 61 of the forming vessel 60, the plurality of heating cartridges 110a-110e can be arranged in and attached to a housing that encloses the forming vessel 60, as described above with respect to Figure 2 and 3 In addition, the plurality of heating cartridges 110a-110e can be operated and controlled as described above with respect to Figure 2 and 3 to adjust the temperature of the molten glass proximate to the trough 61 of the forming vessel 60 to prevent devitrification in the trough 61 and the molten glass flowing through the forming body 61.

[0105] For example, Figure 6 The root temperature response to a single power change is illustratively shown in a mathematical model of a heating cartridge containing molybdenum disilicide as described herein. The model is based on five replaceable heating cartridges (SL1, SL2, SL3, SL4, SL5) each having a heat directing surface 122 at an angle a of about 135° relative to the bottom surface 126 of the heating cartridge. The heating cartridges are modeled to be arranged entirely upstream of the root 70, effectively directing heat onto the root 70. The heating cartridges are configured to span the width of the forming vessel. Each heating cartridge in the model is adjusted one at a time, providing a power increase of 1000 W to the molybdenum disilicide element. In the model, the temperature response to the 1000 W power increase change is measured at a distance of several inches from the inlet dam of the forming vessel (i.e., proximate to the end 64a of the forming vessel 60 shown in Figure 1 .

[0106] Figure 6 The data of FIG. 6 show that individual power adjustment of each heating cartridge can provide controlled control of the temperature of a localized area across the width of the root. For the heating cartridges, the temperature response of the root due to the incremental power change is highest in the localized area of the root closest to the adjusted heating cartridge. As the distance from the adjusted heating cartridge increases, the temperature response of the root decreases, as shown in Figure 6 For example, the temperature response at the inlet dam due to the heating cartridge closest to the inlet dam (SL1) is higher than the temperature response at the inlet dam due to the heating cartridge farthest from the inlet dam (SL5).​Figure 6 The temperature profile (shown as curve SL1) is greatest at the root nearest the inlet dam and decreases as the distance from the inlet dam increases. In addition, as shown in Figure 6 the root by using multiple heating cartridges spaced across the width of the root. For example, as shown in Figure 6 the heating cartridges can be spaced such that the effective heating area of each cartridge overlaps the other, thereby mitigating "cooling points" across the width of the root. That is, in Figure 6 the temperature response curves SL1-SL5 overlap in the widthwise direction at the root, shown as the distance from the inlet dam on the x-axis. This demonstrates that by individually adjusting / controlling the power of the heating cartridges that are correspondingly located in the root region of the forming vessel, any thickness effects or temperature deviations that occur in that region can be easily corrected. Thus, the data show that the multiple segmented and replaceable heating cartridges disclosed herein can be easily adjusted to effectively reduce any devitrification of the drawn glass on the root.

[0107] Continuing with reference to Figures 1-3 and with reference to Figure 10 , a pull roll 130 can be placed downstream of the root 70 of the forming vessel 60 and can be used to adjust the rate at which the formed glass ribbon exits the converging forming surface, thereby helping to determine the nominal thickness of the final sheet. Suitable pull rolls are described, for example, in U.S. Patent No. 6,896,646, which is incorporated herein by reference in its entirety.

[0108] The pull roll can be designed to contact the glass ribbon at its outer edges, specifically at the inner region of the thickening beads that exist at the outer edges of the ribbon. The glass edge portions 140 that are contacted by the pull roll can be later discarded from the substrate after they are separated from the sheet.

[0109] In the drawing apparatus shown in Figure 10 As the glass sheet (glass ribbon) moves down through the draw section of the apparatus, the sheet undergoes complex structural changes, not only in physical dimensions but also at the molecular level. Changing from a soft but thick liquid form (e.g., at the root of the forming wedge) to a rigid glass sheet of the desired thickness can be accomplished by carefully selecting temperature zones that precisely balance the mechanical and chemical requirements to complete the transition from a liquid or viscous state to a solid or elastic state.

[0110] One advantage of the fusion forming process described above is that the glass sheet can be formed without the glass surface contacting any of the refractory forming surfaces. This provides a smooth, contaminant free surface. The fusion forming process also results in a glass sheet having a "fusion line" which is the location where the two glass ribbons that overflow each side of the forming vessel 60 meet and fuse together below the root 70. The fusion line is formed when the two flowing glass films fuse together. The presence of the fusion line is one way of identifying a fusion drawn glass article. The fusion line can be seen as an optical distortion when the glass is viewed under an optical microscope. An advantage of the fusion draw process is that because the two glass films that overflow the channel fuse together, neither outer surface of the resulting glass article has been in contact with any part of the apparatus. Thus, the surface properties of the fusion drawn glass article are not affected by such contact and such exemplary fusion forming techniques are capable of forming flat sheets with high tolerances. However, other sheet forming techniques can also benefit from the present disclosure, including but not limited to, slot draw and redraw forming techniques. In a slot draw technique, molten glass flows into a trough having a machined slot in the bottom. The glass sheet can be pulled down through the slot. The quality of the glass can depend on the precision of the machined slot, among other things. Redraw processes generally involve pre-forming the glass composition into a bulk, and then reheating and drawing the glass into a thinner sheet product.

[0111] Some embodiments of the systems and methods described herein can improve the draw apparatus as shown in Figure 10 by providing one or more sets of edge rolls 210 that can be configured to contact the edges of the glass ribbon when the glass ribbon can be in a viscous region of the draw process. Of course, the embodiments described herein can be applicable to other glass forming processes, such as slot draw processes, double fusion processes, float processes, and the description of some embodiments with reference to the draw process shown should not limit the scope of the appended claims. As shown in Figure 11 At least one of the one or more sets of edge rolls 210 can be oriented to provide an axis of rotation that is at an angle a relative to horizontal or to a line that is perpendicular to the direction of movement and parallel to the plane in which the glass sheet is formed.

[0112] As used herein, each set of edge rolls 210 includes a pair of edge rolls 220, or first pair of edge rolls, configured to contact a first outer edge of the viscous glass ribbon along both the leading side and the trailing side simultaneously. The first pair of edge rolls 220 includes an edge roll that contacts the leading side of the glass ribbon and an edge roll that contacts the trailing side of the glass ribbon.

[0113] Each set of edge rolls 210 can also include a pair of edge rolls 230, or second pair of edge rolls, configured to contact both the first and second outer edges, or opposite outer edges, of the viscous glass ribbon along the front and back sides. The second pair of edge rolls 230 includes an edge roll that contacts the front side of the glass ribbon and an edge roll that contacts the back side of the glass ribbon.

[0114] In some embodiments, either the first pair of edge rolls 220 or the second pair of edge rolls 230 can be oriented to provide an axis of rotation that is at an angle a relative to a horizontal in the fusion draw process or to a line that is perpendicular to the direction of movement and parallel to a plane in which the glass sheet is formed. In other embodiments, both the first pair of edge rolls 220 and the second pair of edge rolls 230 can be oriented to provide an axis of rotation that is at an angle a relative to a horizontal in the fusion draw process or to a line that is perpendicular to the direction of movement and parallel to a plane in which the glass sheet is formed. In other embodiments, neither the first nor second pair of edge rolls 220, 230 are oriented to provide an axis of rotation that forms such an angle. In other embodiments, both the first pair of edge rolls 220 and the second pair of edge rolls 230 can be oriented such that the respective angles a formed are substantially the same.

[0115] In some embodiments, the angle a can be: about 0 degrees to about 55 degrees, about 0 degrees to about 45 degrees, about 0 degrees to about 40 degrees, about 0 degrees to about 35 degrees, about 0 degrees to about 30 degrees, about 0 degrees to about 25 degrees, about 0 degrees to about 15 degrees, and all sub-ranges therebetween. Alternatively, in some embodiments, the angle a can be: about 3-7 degrees to about 55 degrees, about 3-7 degrees to about 45 degrees, about 3-7 degrees to about 40 degrees, about 3-7 degrees to about 35 degrees, about 3-7 degrees to about 30 degrees, about 3-7 degrees to about 25 degrees, about 5-7 degrees to about 15 degrees, and all sub-ranges therebetween.

[0116] The first pair of edge rolls 220 and the second pair of edge rolls 230 can be aligned longitudinally at a first location 240 below a root of the fusion draw process or aligned with each other along the direction of movement of the glass sheet. In an exemplary fusion draw embodiment, the location 240 can be based on a line extending horizontally between a center of an inward end of the first pair of edge rolls 220 and a center of an inward end of the second pair of edge rolls 230 or can be based on a line extending perpendicular to the direction of movement and parallel to a plane in which the glass sheet is formed. The location 240 can be in a region where the glass ribbon is in a viscous state.

[0117] In some embodiments, the longitudinal position 240 may be arranged near the root 70. As used herein, the root 70 refers to the location where, in a fusion-drawing embodiment, the separate glass streams converge to form a sheet or strip of the plain-surface glass 121. Thus, in embodiments that include a projection of an edge guide extending below the bottom of the inclined converging surface portions 66a, 66b (e.g., the type described in US 3,537,834, the entire text of which is incorporated herein by reference), the root 70 can be considered as the tip of the edge guide projection, where the separate glass streams converge at the fusion line.

[0118] In some embodiments, for example, the longitudinal or horizontal position 240 may be from about 3 cm to about 30 cm below the root 70. Alternatively, the longitudinal or horizontal position 240 may be: from about 3 cm to about 25 cm below the root 70, from about 3 cm to about 20 cm below the root 70, from about 3 cm to about 18 cm below the root 70, from about 3 cm to about 16 cm below the root 70, from about 3 cm to about 14 cm below the root 70, from about 3 cm to about 12 cm below the root 70, from about 3 cm to about 10 cm below the root 70, and all sub-ranges therein.

[0119] Replacing the set of edge rollers 210 near the root 70 may be particularly advantageous for preventing or minimizing sheet width variations, since lateral shrinkage of the strip edge immediately below the root 70 is believed to be the primary factor causing sheet width variations. Therefore, by arranging a set of edge rollers 210 near the root 70, sheet thickness variations can be completely minimized or prevented. Thus, in some embodiments, the longitudinal or horizontal position 240 can be: less than 25 cm below the root 70, less than 20 cm below the root 70, less than 18 cm below the root 70, less than 16 cm below the root 70, less than 14 cm below the root 70, less than 12 cm below the root 70, less than 10 cm below the root 70, and all sub-ranges therein.

[0120] In some implementations, more than one set of edge rollers 210 may be provided. For example, such as Figure 12 As shown, a first set of edge rollers 210a and a second set of edge rollers 210b can be provided. Although not shown, in embodiments of the systems and methods described herein, it is conceivable that any number of additional sets of edge rollers can be provided. For example, embodiments may include 3 sets of edge rollers, 4 sets of edge rollers, etc.

[0121] As with the first set of edge rolls 210a, the second set of edge rolls 210b includes a pair of edge rolls 250, or a third pair of edge rolls, configured to simultaneously contact the first outer edge of the viscous glass ribbon along the front side and the back side. The third pair of edge rolls 250 includes an edge roll that contacts the front side of the glass ribbon and an edge roll that contacts the back side of the glass ribbon.

[0122] The second set of edge rolls 210b can also include a pair of edge rolls 260, or a fourth pair of edge rolls, configured to simultaneously contact the second outer edge, or opposite outer edge, of the viscous glass ribbon along the front side and the back side. The fourth pair of edge rolls 260 includes an edge roll that contacts the front side of the glass ribbon and an edge roll that contacts the back side of the glass ribbon.

[0123] Any of the third pair of edge rolls 250 and / or the fourth pair of edge rolls 260 can be oriented to provide an axis of rotation that is at an angle β with respect to the horizontal in the fusion draw process or with respect to a line that is at a right angle to the direction of movement and parallel to the plane in which the glass sheet is formed. In some embodiments, both the third pair of edge rolls 250 and the fourth pair of edge rolls 260 can be oriented to provide an axis of rotation that is at an angle with respect to the horizontal in the fusion draw process or with respect to a line that is at a right angle to the direction of movement and parallel to the plane in which the glass sheet is formed. In other embodiments, neither the third nor the fourth pair of edge rolls 250, 260 are angled in this manner. In other embodiments, both the third pair of edge rolls 250 and the fourth pair of edge rolls 260 are oriented such that the respective angles β formed are substantially the same.

[0124] In some embodiments, the angle β can be: about 0 degrees to about 55 degrees, about 0 degrees to about 45 degrees, about 0 degrees to about 40 degrees, about 0 degrees to about 35 degrees, about 0 degrees to about 30 degrees, about 0 degrees to about 25 degrees, about 0 degrees to about 15 degrees, and all sub-ranges therebetween. In other embodiments, the angle β can be: about 3-7 degrees to about 55 degrees, about 3-7 degrees to about 45 degrees, about 3-7 degrees to about 40 degrees, about 3-7 degrees to about 35 degrees, about 3-7 degrees to about 30 degrees, about 3-7 degrees to about 25 degrees, about 3-7 degrees to about 15 degrees, and all sub-ranges therebetween. Alternatively, in other embodiments, the angle β can be: about 15 degrees to about 55 degrees, about 15 degrees to about 45 degrees, about 15 degrees to about 40 degrees, about 15 degrees to about 35 degrees, about 15 degrees to about 30 degrees, about 0 degrees to about 25 degrees, and all sub-ranges therebetween.

[0125] In some embodiments, the second set of edge rolls 210b can be oriented at an angle β that is different than the angle a at which the first set of edge rolls 210a can be oriented. For example, it can be desirable to configure the second set of edge rolls 210b to form an angle β that can be greater than the angle a. In some embodiments, for example, the first set of edge rolls 210a can be oriented to form an angle of about 3 degrees to about 20 degrees, while the second set of edge rolls 210b can be oriented to form an angle of about 15 degrees to about 40 degrees. Alternatively, the first set of edge rolls 210a can be oriented to form an angle of about 3 degrees to about 12 degrees, while the second set of edge rolls 210b can be oriented to form an angle of about 15 degrees to about 30 degrees. Of course, these embodiments are merely exemplary and should not limit the scope of the claims appended hereto.

[0126] The third and fourth sets of edge rolls 250, 260 can be longitudinally aligned at a second location 270 in the fusion draw process or aligned with one another along the direction of movement of the glass sheet. In an exemplary fusion draw embodiment, the second location 270 can be based on a line extending horizontally between the center of the inward end of the third set of edge rolls 250 and the center of the inward end of the fourth set of edge rolls 260, or can be based on a line extending perpendicular to the direction of movement and parallel to the plane in which the glass sheet is formed. The second location 270 can be in a region where the glass ribbon is in a viscous state, but below the first location 240.

[0127] In some embodiments, the second location 270 can be: about 12 cm to about 50 cm below the root 70, about 15 cm to about 50 cm below the root 70, about 15 cm to about 45 cm below the root 70, about 15 cm to about 40 cm below the root 70, about 15 cm to about 30 cm below the root 70, about 20 cm to about 45 cm below the root 70, about 20 cm to about 40 cm below the root 70, about 30 cm to about 45 cm below the root 70, about 30 cm to about 50 cm below the root 70, and all sub-ranges therebetween.

[0128] In some embodiments, the second location 270 can be less than 24 cm below the first location 240, less than 22 cm below the first location, less than 20 cm below the first location, less than 18 cm below the first location, less than 16 cm below the first location, etc.

[0129] Each set of edge rolls 210 can be independently configured to operate in either a constant speed mode or a constant torque mode. For example, when there are sheet width variations / instabilities, the torque of an edge roll operating in constant speed mode can vary in an oscillatory pattern and cycle in a manner consistent with the sheet width variations. Thus, the constant torque mode can be used in a controlled manner to maintain the tension applied by the edge rolls, and in some embodiments, it can be desirable to have the first set of edge rolls 210a operate in constant torque mode and the second set of edge rolls 210b operate in constant speed mode.

[0130] Each set of edge rolls 210 can be independently configured to include either a very smooth contact surface or a textured surface. The texture on an exemplary edge roll can be used to grip the glass sheet and avoid slippage (as well as provide additional cooling). However, Applicants have noted that when more than one set of edge rolls is used, it has been observed that when both sets of edge rolls have a textured pattern, there is a concern that the second set of edge rolls can become difficult to grip the glass sheet. Thus, in some embodiments, it can be desirable to provide one of the first set of edge rolls 210a and the second set of edge rolls 210b with a textured surface, and the other of the first set of edge rolls and the second set of edge rolls with a very smooth surface.

[0131] By selecting the inclination and position of the one or more sets of edge rolls 210, the sheet width attenuation of the drawn sheet glass can be reduced. The sheet width attenuation of the drawn sheet glass can be reduced by mitigating the amount of lateral contraction of the glass ribbon such that the resulting sheet glass has a width that is greater than the width of the glass ribbon at the root using conventional orientation edge rolls or without the use of edge rolls. However, as used herein, the sheet width attenuation of the drawn sheet glass can also be reduced in situations where: (a) the lateral contraction of the glass ribbon is completely prevented such that the resulting sheet glass has a width that is substantially the same as the width of the glass ribbon at the root (i.e., zero sheet width attenuation); and (b) the sheet is stretched such that the resulting sheet glass has a width that is greater than the width of the glass ribbon at the root.

[0132] By selecting the inclination and position of the one or more sets of edge rolls 210, sheet glass having a width that is at least about 90% of the width of the viscous glass ribbon at the root can be produced. Alternatively, sheet glass having a width that is at least about 92% of the width of the viscous glass ribbon at the root, at least about 94% of the width of the viscous glass ribbon at the root, at least about 95% of the width of the viscous glass ribbon at the root, at least about 96% of the width of the viscous glass ribbon at the root, at least about 97% of the width of the viscous glass ribbon at the root, at least about 98% of the width of the viscous glass ribbon at the root, at least about 99% of the width of the viscous glass ribbon at the root, or the same as the width of the viscous glass ribbon at the root can be produced, thereby effectively preventing sheet width attenuation.

[0133] In some embodiments, by selecting the tilt and position of the one or more sets of edge rolls 210, sheet glass can be produced having a width that is greater than the width of the viscous glass ribbon at the root. In addition to effectively preventing sheet width decay, by controlling the tilt and position of the one or more sets of edge rolls 210, the sheet width can be elongated. For example, sheet glass having a width that is at least about 100%, at least about 102%, at least about 104%, or at least about 105% of the width of the viscous glass ribbon at the root can be produced.

[0134] In addition, by selecting the tilt and position of the one or more sets of edge rolls 210, the thickness of the beads known to form along the edges of the glass sheet can be reduced. As described above, an increase in edge bead thickness and any slower cooling that results from the increased thickness can lead to a number of problems related to sheet stability. Thus, reducing the edge bead thickness can result in increased ribbon and glass sheet stability.

[0135] In some embodiments, the ratio of bead thickness to center thickness can be used as an indication of the degree of bead thickness reduction. Using the embodiments of the disclosure described herein, by selecting the tilt and position of the one or more sets of edge rolls 210, glass sheets having a ratio of bead thickness to center thickness of less than 12: 1 can be produced. Alternatively, glass sheets having a ratio of bead thickness to center thickness of less than 10: 1, less than 8: 1, less than 6: 1, less than 5: 1, less than 4: 1, less than 3: 1, less than 2.5: 1, less than 2: 1, less than 1.5: 1, and all sub-ranges therebetween can be produced.

[0136] Sheet width variation can also be reduced by selecting the tilt and position of the one or more sets of edge rolls 210 and the relative distance between different sets of edge rolls and the relative speed between different sets of edge rolls. For example, as described above, it can be desirable to replace at least one set of edge rolls 210 near the root to prevent any decay that occurs immediately above the root, and this can be a key driver for sheet width variation. In another example, the first set of edge rolls can be determined based on the root state rather than the pull speed to avoid excessive tension on the glass near the root that can cause the glass flow over the edge guides to flow separate, particularly when forming ultra-thin glass (e.g., < 200 microns, < 100 microns, etc.). A second set of edge rolls can also be used to decouple any effects of the pull rolls from the first set of edge rolls.

[0137] As used herein, reducing sheet width variation can include those embodiments in which sheet width variation is effectively eliminated. In some embodiments, sheet width variation can be measured by recording the position of the outermost edges of the sheet, for example, by a camera typically mounted at the draw bottom. Sheet width variation can also be indicated by tracking the longitudinal velocity of the viscous glass at various points within the drawn glass ribbon. This can be accomplished, for example, by plotting the longitudinal velocity at various points to obtain a longitudinal velocity profile across the width (or a portion of the width) of the glass ribbon in the viscous region. Of course, these plots of longitudinal velocity are similar for horizontal velocity in embodiments having a transverse direction of movement (float process). When the longitudinal velocity profile increases in a substantially parallel manner across the width of the glass ribbon, sheet width variation can be reduced or avoided.

[0138] By selecting the tilt and position of the one or more sets of edge rolls 210, a substantially parallel longitudinal velocity profile within the viscous region during the drawing process can be obtained. These profiles indicate a very smooth and continuous increase in glass velocity in the direction. Thus, by selecting the tilt and position of the one or more sets of edge rolls 210, sheet width variation can be reduced or eliminated.

[0139] It has also been found that even in the absence of tilted edge rolls, an additional second set of edge rolls 210b positioned a short distance below the first set of edge rolls 210a is itself advantageous for reducing sheet width decay, sheet width variation, and edge bead. Thus, in some embodiments, either of the first set of edge rolls 210a and the second set of edge rolls 210b can be oriented such that the axis of rotation is horizontal in the fusion draw process, or is in a line that is at a right angle to the direction of movement and parallel to the plane in which the glass sheet is formed. The second set of edge rolls 210b can be positioned to create an effective transverse draw tension prior to final sheet width and / or thickness fixation.

[0140] Referring now to Figure 13 and 14 schematic front and side views of an exemplary embodiment of a glass manufacturing apparatus 301 that can be used in aspects of the disclosure are shown. The glass manufacturing apparatus 301 is shown as a down-draw fusion apparatus, although other forming apparatuses can be used in other examples. In one example, the glass manufacturing apparatus 301 can include a forming vessel 60 to produce a glass ribbon 121 including a width "W" extending between a first edge portion 121a and a second edge portion 121b of the glass ribbon 121.

[0141] As Figure 13 and 14Further shown, the glass manufacturing apparatus 301 can include a pull roll device 315 and a separation device 319. A portion of the glass ribbon 121 is pulled from the root 70 of the forming vessel 60 into a viscous zone 341, where the glass ribbon 121 begins to thin to a final thickness. The portion of the glass ribbon 121 is then pulled from the viscous zone 341 into a solidification zone 343 (a visco-elastic zone). In the solidification zone 343, the portion of the glass ribbon 121 solidifies from a viscous state to an elastic state having a desired profile. The portion of the glass ribbon 121 is then drawn from the solidification zone 343 into an elastic zone 345. Once in the elastic zone 345, the glass ribbon 121 can be deformed to a limited extent without permanently changing the profile of the glass ribbon 121.

[0142] After the portion of the glass ribbon 121 enters the elastic zone 345, the separation device 319 can be provided to sequentially separate a plurality of glass sheets 347a, 347b from the glass ribbon 121 over a period of time. The separation device 319 can include a moving anvil as shown, but other separation devices can be provided in other examples.

[0143] The glass manufacturing apparatus 301 also includes a pull roll device 315, as Figure 13 and 14 schematically shown. As discussed in greater detail below, the pull roll device 315 can be provided to assist in drawing the glass ribbon 121 from the root 70 and can isolate forces on the glass ribbon 121 from being transmitted from the elastic zone 345 to the solidification zone 343. In this manner, the pull roll device of the present disclosure can draw the glass ribbon to a desired thickness while also reducing residual stresses in the glass sheets. As shown, the pull roll device 315 can be located within the viscous zone 341, the solidification zone 343, and the elastic zone 345. In fact, as shown in the figures, a first pull roll apparatus is located within the viscous zone 341, or can be located at the top of the solidification zone 343 adjacent to the viscous zone 341, as discussed in greater detail below. A second pull roll apparatus is located within the solidification zone 343, as discussed in greater detail below, and a third pull roll apparatus is located within the elastic zone 345, as discussed in greater detail below.

[0144] Figure 13 , Figure 14 and Figure 15 show a first example of a pull roll device 315 according to one example embodiment of the present disclosure, but other pull roll device 315 configurations can be provided in other examples. The pull roll device 315 can include a first pull roll apparatus 349 including a first upstream draw roll pair 351 configured to draw a first edge portion 121a of the glass ribbon 121 from the forming vessel 60 along a draw path 353 that extends across a width "W" of the glass ribbon 121.

[0145] As shown, the first upstream draw roll pair 351 can include a first pull roll element 355a and a second pull roll element 355b. The first and second pull roll elements 355a, 355b can be provided with respective refractory roll covers 357a, 357b configured to engage the first edge portion 121a of the glass ribbon 121 therebetween. At least one of the first and second pull roll elements 355a, 355b can be provided with a respective motor 359a, 359b. For example, as shown, both the first and second pull roll elements 355a, 355b are provided with respective motors 359a, 359b. In other examples, only one of the first and second pull roll elements 355a, 355b is provided with a motor, wherein the other pull roll element can be provided with a bearing such that only one of the first and second pull roll elements 355a, 355b is driven.

[0146] In another example, in addition to or in lieu of the first upstream draw roll pair 351, the first pull roll apparatus 349 can include a second upstream draw roll pair 361 configured to draw the second edge portion 121b of the glass ribbon 121 from the forming vessel 70 along the draw path 353. As shown, the second upstream draw roll pair 361 can include a first pull roll element 363a and a second pull roll element 363b. The first and second pull roll elements 363a, 363b can be provided with respective refractory roll covers 365a, 365b configured to engage the second edge portion 121b of the glass ribbon 121 therebetween. At least one of the first and second pull roll elements 363a, 363b can be provided with a respective motor 367a, 367b. For example, as shown, both the first and second pull roll elements 363a, 363b are provided with respective motors 367a, 367b. In other examples, only one of the first and second pull roll elements 367a, 367b is provided with a motor, wherein the other pull roll element can be provided with a bearing such that only one of the first and second pull roll elements 367a, 367b is driven.

[0147] As Figure 13 , Figure 14 and Figure 16As shown, the pull roll apparatus 315 further includes a second pull roll device 369 including a first midstream pull roll pair 371 positioned downstream of the first upstream pull roll pair 351 along the draw path 353, where the first midstream pull roll pair 371 is configured to further draw the first edge portion 121a of the glass ribbon 121 along the draw path 353. As shown, the first midstream pull roll pair 371 can include a first pull roll member 373a and a second pull roll member 373b. The first and second pull roll members 373a, 373b can be provided with respective refractory roll covers 375a, 375b configured to engage the first edge portion 121a of the glass ribbon 121 therebetween. At least one of the first and second pull roll members 373a, 373b can be provided with a respective motor 377a, 377b. For example, as shown, both the first and second pull roll members 373a, 373b are provided with respective motors 377a, 377b. In other examples, only one of the first and second pull roll members 373a, 373b is provided with a motor, where the other pull roll member can be provided with a bearing such that only one of the first and second pull roll members 373a, 373b is driven.

[0148] In another example, in addition to or in lieu of the first midstream pull roll pair 371, the second pull roll device 369 can include a second midstream pull roll pair 379 positioned downstream of the second upstream pull roll pair 361 along the draw path 353, where the second midstream pull roll pair 379 is configured to further draw the second edge portion 121b of the glass ribbon 121 along the draw path 353. As shown, the second midstream pull roll pair 379 can include a first pull roll member 381a and a second pull roll member 381b. The first and second pull roll members 381a, 381b can be provided with respective refractory roll covers 383a, 383b configured to engage the second edge portion 121b of the glass ribbon 121 therebetween. At least one of the first and second pull roll members 381a, 381b can be provided with a respective motor 385a, 385b. For example, as shown, both the first and second pull roll members 381a, 381b are provided with respective motors 385a, 385b. In other examples, only one of the first and second pull roll members 381a, 381b is provided with a motor, where the other pull roll member can be provided with a bearing such that only one of the first and second pull roll members 381a, 381b is driven.

[0149] As Figure 13 , Figure 14 and Figure 17As shown, the pull roll apparatus 315 further includes a third pull roll device 387 including a first downstream draw roll pair 389 positioned downstream of the first midstream draw roll pair 371 along the draw path 353, where the first downstream draw roll pair 389 is configured to further draw the first edge portion 121a of the glass ribbon 121 along the draw path 353. As shown, the first downstream draw roll pair 389 can include a first pull roll member 391a and a second pull roll member 391b. The first and second pull roll members 391a, 391b can be provided with respective refractory roll covers 393a, 393b configured to engage the first edge portion 121a of the glass ribbon 121 therebetween. At least one of the first and second pull roll members 391a, 391b can be provided with a respective motor 395a, 395b. For example, as shown, both the first and second pull roll members 391a, 391b are provided with respective motors 395a, 395b. In other examples, only one of the first and second pull roll members 391a, 391b is provided with a motor, where the other pull roll member can be provided with a bearing such that only one of the first and second pull roll members 391a, 391b is driven.

[0150] In another example, in addition to or in lieu of the first downstream draw roll pair 389, the third pull roll device 387 can include a second downstream draw roll pair 397 positioned downstream of the second midstream draw roll pair 379 along the draw path 353, where the second downstream draw roll pair 397 is configured to further draw the second edge portion 121b of the glass ribbon 121 along the draw path 353. As shown, the second downstream draw roll pair 397 can include a first pull roll member 399a and a second pull roll member 399b. The first and second pull roll members 399a, 399b can be provided with respective refractory roll covers 401a, 401b configured to engage the second edge portion 121b of the glass ribbon 121 therebetween. At least one of the first and second pull roll members 399a, 399b can be provided with a respective motor 403a, 403b. For example, as shown, both the first and second pull roll members 399a, 399b are provided with respective motors 403a, 403b. In other examples, only one of the first and second pull roll members 399a, 399b is provided with a motor, where the other pull roll member can be provided with a bearing such that only one of the first and second pull roll members 399a, 399b is driven. It should be appreciated that the pull roll apparatus 315 can further include optional edge roll pairs 402 (402a, 404b) and 404, and / or optional idler short roll pairs 406, 408 (see FIGS. 1 and 2), as described above. Figure 13 、 14 and 18).

[0151] like Figure 18 and 19 As shown, the traction roller device 315 may further include an intermediate traction roller device 405, which includes a first intermediate drawing roller pair 407 located downstream of the first midstream drawing roller pair 371 along the drawing path 353 and upstream of the first downstream drawing roller pair 389 along the drawing path. The first intermediate drawing roller pair 407 is configured to further draw the first edge portion 121a of the glass ribbon 121 along the drawing path 353. As shown, the first intermediate drawing roller pair 407 may include a first traction roller element 409a and a second traction roller element 409b. The first and second traction roller elements 409a and 409b may each be provided with their respective refractory roller covers 411a and 411b, configured to engage the first edge portion 121a of the glass ribbon 121 therebetween. At least one of the first and second traction roller elements 409a and 409b may be provided with its respective motor 413a and 413b. For example, as shown, both the first and second pull roller elements 413a and 413b are provided with their own motors 413a and 413b. In other examples, only one of the first and second pull roller elements 409a and 409b is provided with a motor, wherein the other pull roller elements are provided with bearings, such that only one of the first and second pull roller elements 409a and 409b is driven.

[0152] In another example, as a supplement to or alternative to the first intermediate drawing roller pair 407, the intermediate drawing roller device 405 may include a second intermediate drawing roller pair 415, which is located downstream of the second midstream drawing roller pair 379 along the drawing path 353 and upstream of the second downstream drawing roller pair 397 along the drawing path 353. The second midstream drawing roller pair 415 is configured to further draw the second edge portion 121b of the glass ribbon 121 along the drawing path 353. As shown, the second intermediate drawing roller pair 415 may include a first drawing roller element 417a and a second drawing roller element 417b. The first and second drawing roller elements 417a and 417b may each be provided with their respective refractory roller covers 419a and 419b, configured to engage the second edge portion 121b of the glass ribbon 121 therebetween. At least one of the first and second drawing roller elements 417a and 417b may be provided with its respective motor 421a and 421b. For example, as shown, both the first and second pull roller elements 417a and 417b are provided with their own motors 421a and 421b. In other examples, only one of the first and second pull roller elements 417a and 417b is provided with a motor, wherein the other pull roller elements are provided with bearings, so that only one of the first and second pull roller elements 417a and 417b is driven.

[0153] Although the position of the intermediate pull roll apparatus 405 is shown and described as being at a fourth elevation between the second pull roll apparatus 369 and the third pull roll apparatus 387, the present disclosure is not limited to these example embodiments. The intermediate pull roll apparatus 405 can be positioned at various elevations of the pull roll arrangement 315. Moreover, the intermediate pull roll apparatus 405 can be modular such that multiple pull roll apparatuses 405 can be included in the pull roll arrangement 315 and positioned at various elevations along the draw path 353.

[0154] Although each draw roll pair is described as including a first and second pull roll element, the first and second pull roll elements can also be referred to as draw rolls of the draw roll pair.

[0155] The pull roll arrangement 315 of the glass manufacturing apparatus 301 can also include a control device 423 (e.g., a programmable logic controller) configured to independently operate the first pull roll apparatus 349, the second pull roll apparatus 369, and the third pull roll apparatus 387 such that at least one of the first upstream draw roll pair 351 rotates at a substantially constant torque, at least one of the first midstream draw roll pair 371 rotates at a substantially constant torque, and at least one of the first downstream draw roll pair 389 rotates at a substantially constant angular velocity. The control device 423 can communicate 425 with the pull roll apparatuses 349, 369, 387, 405 via a cable, a wireless network, a wired network, combinations thereof, and the like. For the purposes of the present disclosure, independently operating the first, second, and third pull roll apparatuses 349, 369, and 387 means that one of the first, second, and third pull roll apparatuses can be operated without being affected by the operation of the other of the first, second, and third pull roll apparatuses. Thus, for example, independently operating the first pull roll apparatus 349 with the control device 423 provides the control device to operate the first pull roll apparatus 349 without regard to changes in the operating parameters of the second pull roll apparatus 369 or the third pull roll apparatus 387. Moreover, for example, independently operating the second pull roll apparatus 369 with the control device 423 provides the control device to operate the second pull roll apparatus 369 without regard to changes in the operating parameters of the first pull roll apparatus 349 or the third pull roll apparatus 387. Additionally, for example, independently operating the third pull roll apparatus 387 with the control device 423 provides the control device to operate the third pull roll apparatus 387 without regard to changes in the operating parameters of the first pull roll apparatus 349 or the second pull roll apparatus 369.

[0156] As described above, the first upstream draw roll pair 351 can include a single motor associated with one of the first or second pull roll elements 355a, 355b. In such examples, the control device 423 can operate the single motor such that the associated first or second pull roll element 355a, 355b rotates with a substantially constant torque. As further described above, the first and second pull roll elements 355a, 355b can be respectively provided with corresponding motors 359a, 359b. In such examples, the control device 423 can operate the motors 359a, 359b such that at least one (e.g., both) of the first upstream draw roll pair 351 rotates with a substantially constant torque. Rotating both pull roll elements 359a, 359b of the first upstream draw roll pair 351 with a substantially constant torque can be desirable to apply equal forces to both sides of the first edge portion 121a of the glass ribbon 121.

[0157] As described above, the first pull roll apparatus 349 can also include an optional second upstream draw roll pair 361. In such examples, the second upstream draw roll pair 361 can include a single motor associated with one of the first or second pull roll elements 363a, 363b. In such examples, the control device 423 can operate the single motor such that the associated first or second pull roll element 363a, 363b rotates with a substantially constant torque. As further described above, the first and second pull roll elements 363a, 363b can be respectively provided with corresponding motors 367a, 367b. In such examples, the control device 423 can operate the motors 367a, 367b such that at least one (e.g., both) of the second upstream draw roll pair 361 rotates with a substantially constant torque. Rotating both pull roll elements 363a, 363b of the second upstream draw roll pair 361 with a substantially constant torque can be desirable to apply equal forces to both sides of the second edge portion 121b of the glass ribbon 121.

[0158] While not required, in some examples the control device 423 can operate one or both motors associated with the first upstream draw roll pair 351 with a substantially constant first torque, and can simultaneously operate one or both motors associated with the second upstream draw roll pair 361 to rotate with a substantially constant second torque that is substantially equal to the first torque. Providing substantially equal first and second torques can be desirable, for example, to apply substantially the same forces to the glass ribbon 121 and the first and second edge portions 121a, 121b.

[0159] As noted above, the second pull roll apparatus 369 can also include an optional second midstream draw roll pair 379. In such examples, the second midstream draw roll pair 379 can include a single motor associated with one of the first or second pull roll elements 381a, 381b. In such examples, the control device 423 can operate the single motor such that the associated first or second pull roll element 381a, 381b rotates with a substantially constant torque. As further noted above, the first and second pull roll elements 381a, 381b can be respectively provided with corresponding motors 385a, 385b. In such examples, the control device 423 can operate the motors 385a, 385b such that at least one (e.g., both) of the second midstream draw roll pair 379 rotates with a substantially constant torque. Having both pull roll elements 381a, 381b of the second midstream draw roll pair 379 rotate with a substantially constant torque can be desirable to apply equal forces to both sides of the second edge portion 121b of the glass ribbon 121.

[0160] While not required, in some examples, the control device 423 can operate one or both motors associated with the first midstream draw roll pair 371 with a substantially constant first torque, and can simultaneously operate one or both motors associated with the second midstream draw roll pair 379 to rotate with a substantially constant second torque that is substantially equal to the first torque. Providing substantially equal first and second torques can be desirable to, for example, apply substantially the same forces to the glass ribbon 121 and the first and second edge portions 121a, 121b.

[0161] As noted above, the first downstream draw roll pair 389 can include a single motor associated with one of the first or second pull roll elements 391a, 391b. In such examples, the control device 423 can operate the single motor such that the associated first or second pull roll element 391a, 391b rotates with a substantially constant angular velocity. As further noted above, the first and second pull roll elements 391a, 391b can be respectively provided with corresponding motors 395a, 395b. In such examples, the control device 423 can operate the motors 395a, 395b such that at least one (e.g., both) of the first downstream draw roll pair 389 rotates with a substantially constant angular velocity. Having both pull roll elements 391a, 391b of the first downstream draw roll pair 389 rotate with a substantially constant angular velocity can be desirable to equally draw the glass ribbon on both sides of the first edge portion 121a of the glass ribbon 121.

[0162] As noted above, the third pull roll apparatus 387 can also include an optional second downstream draw roll pair 397. In such examples, the second downstream draw roll pair 397 can include a single motor associated with one of the first or second pull roll elements 399a, 399b. In such examples, the control device 423 can operate the single motor such that the associated first or second pull roll element 399a, 399b rotates at a substantially constant angular velocity. As further noted above, the first and second pull roll elements 399a, 399b can be provided with respective motors 403a, 403b. In such examples, the control device 423 can operate at least one (e.g., both) of the second downstream draw roll pair 397 to rotate at a substantially constant angular velocity. Having both of the pull roll elements 399a, 399b of the second downstream draw roll pair 397 rotate at a substantially constant angular velocity can be desirable for equally drawing the glass ribbon on both sides of the second edge portion 121b of the glass ribbon 121.

[0163] While not required, in some examples, the control device 423 can operate one or both of the motors associated with the first downstream draw roll pair 389 at a substantially constant first angular velocity, and can simultaneously operate one or both of the motors associated with the second downstream draw roll pair 397 to rotate at a substantially constant second angular velocity that is substantially equal to the first angular velocity. Providing substantially equal first and second angular velocities can be desirable, for example, for equally drawing the glass ribbon at the first and second edge portions 121a, 121b.

[0164] As noted, the control device 423 can be configured to independently operate the first pull roll apparatus 349 such that at least one of the first and second upstream draw roll pairs 351, 361 rotates at a substantially constant torque; however, embodiments are not limited in this respect. That is, in exemplary embodiments, the control device 423 can be configured to independently operate the first pull roll apparatus 349 such that at least one of the first and second upstream draw roll pairs 351, 361 does not rotate at a constant torque, but rather rotates at a substantially constant angular velocity. Further, the control device 423 can be configured to independently operate the second pull roll apparatus 369 such that at least one of the first and second midstream draw roll pairs 371, 379 does not rotate at a constant torque, but rather rotates at a substantially constant angular velocity.

[0165] The control device 423 can also be configured to independently operate the intermediate pull roll apparatus 405 such that at least one of the first and second intermediate draw roll pairs 407, 415 rotates at a substantially constant torque. Alternatively, the control device 423 can be configured to independently operate the intermediate pull roll apparatus 405 such that at least one of the first and second intermediate draw roll pairs 407, 415 does not rotate at a constant torque, but rather rotates at a substantially constant angular velocity.

[0166] Table 1 provides five different independent control schemes in accordance with example embodiments of the present disclosure. For example, as shown in Table 1, control scheme "A" includes control device 423 configured to independently operate first pull roll apparatus 349 such that at least one of first and second upstream draw rolls 351, 361 rotates with a substantially constant torque, to independently operate second pull roll apparatus 369 such that at least one of first and second midstream draw rolls 371, 379 rotates with a substantially constant torque, to independently operate third pull roll apparatus 387 such that at least one of first and second downstream draw rolls 389, 397 rotates with a substantially constant angular velocity, and to control device 423 configured to independently operate intermediate pull roll apparatus 405 (if provided) such that at least one of first and second intermediate draw rolls 407, 415 rotates with a substantially constant torque or such that at least one of first and second intermediate draw rolls 407, 415 does not rotate with a constant torque but rather rotates with a substantially constant angular velocity.

[0167] As another example shown in Table 1, control scheme "E" includes control device 423 configured to independently operate first pull roll apparatus 349 such that at least one of first and second upstream draw rolls 351, 361 rotates with a substantially constant torque, to independently operate second pull roll apparatus 369 such that at least one of first and second midstream draw rolls 371, 379 rotates with a substantially constant torque, to independently operate third pull roll apparatus 387 such that at least one of first and second downstream draw rolls 389, 397 rotates with a substantially constant torque, and to control device 423 configured to independently operate intermediate pull roll apparatus 405 (if provided) such that at least one of first and second intermediate draw rolls 407, 415 rotates with a substantially constant torque.

[0168] Table 1

[0169]

[0170] In some examples, the draw rolls pairs discussed throughout this application can have a similar configuration and orientation as that of Anderson et al., U.S. Patent Application Publication No. 2009 / 0107182, published April 30, 2009, which is incorporated herein by reference in its entirety. For example, any of the draw roll pairs can be down-tilted or horizontally transverse rolls with respect to the longitudinal direction of the glass ribbon. In addition, as Figure 15 and 16As shown, any pair of rollers (laterally horizontal or inclined) can be positioned at a predetermined horizontal angle θ, such that the respective faces of the rollers are positioned relative to the respective main surfaces 427, 429 of the glass belt 121. It may be desirable for the horizontal angle θ to provide a suitable level of lateral tensile tension 431 and / or to accommodate the tapering effect that may occur during normal roller wear.

[0171] Figure 13 and 18 The following example illustrates that each of the first pull roller elements 355a, 363a, 373a, 381a, 391a, 399a, 409a, and 417a of the pull roller pair may include a roller inclined downward relative to the longitudinal direction of the glass ribbon 121. The second pull roller elements 355b, 363b, 373b, 381b, 391b, 399b, 409b, and 417b of the pull roller pair may similarly include rollers inclined downward relative to the longitudinal direction of the glass ribbon 121. Depending on process considerations, the downward inclination angle of any pull roller pair may be different from or the same as any other pull roller pair. The downward inclination of the first and / or second upstream pull roller pairs 351 and 361 can provide the desired level of cross-tension 431 between the two pull roller pairs 351 and 361. The downward inclination of the first and / or second midstream pulling roller pairs 371, 379 can provide the desired level of lateral pulling tension 433 between the two pairs of pulling roller pairs 371, 379. The downward inclination of the first and / or second downstream pulling roller pairs 389, 397 can provide the desired level of lateral pulling tension 435 between the two pairs of pulling roller pairs 389, 397. Similarly, the downward inclination of the first and / or second intermediate pulling roller pairs 407, 415 can provide the desired level of lateral pulling tension 437 between the two pairs of pulling roller pairs 407, 415.

[0172] In some examples, control device 423 may be configured to activate an automatic positioner (not shown) or a manual mechanism may be used to adjust the downward tilt position of the longitudinally tilting roller, thereby controlling (or adjusting) the average lateral tension 431, 433, 435, 437 on the glass belt 121.

[0173] In other examples, one or more of the drawing roller pairs 351, 361, 371, 379, 389, 397, 407, and 415 may be horizontal rollers relative to the glass ribbon, wherein the axis of rotation of the drawing roller extends substantially perpendicular to the drawing path of the glass ribbon 121. If lateral tension along the width of the glass ribbon along the roller pair is not required, it may be desirable to provide one or two drawing roller pairs as laterally horizontal rollers.

[0174] The following will be relative to Figures 13-19 The method of manufacturing glass ribbon 121 is described using the pull roller device 315 shown.

[0175] Referring to Figure 13 , 14 and 15, the method can include the step of providing a first draw roll apparatus 349 comprising a first upstream draw roll pair 351. In another example, the first draw roll apparatus 349 can optionally be provided with a second upstream draw roll pair 361.

[0176] Referring to Figure 13 , 14 and 16, the method further includes the step of providing a second draw roll apparatus 369 comprising a first midstream draw roll pair 371 located downstream of the first upstream draw roll pair 351 along the draw path 353. In another example, the second draw roll apparatus 369 can optionally be provided with a second midstream draw roll pair 379 located downstream of the second upstream draw roll pair 361 along the draw path 353.

[0177] The method further includes the step of providing a third draw roll apparatus 387 comprising a first downstream draw roll pair 389 located downstream of the first midstream draw roll pair 371 along the draw path 353. In another example, the third draw roll apparatus 387 can optionally be provided with a second downstream draw roll pair 397 located downstream of the second midstream draw roll pair 379 along the draw path 353.

[0178] Optionally, the method can further include the step of providing an intermediate draw roll apparatus 405 comprising a first intermediate draw roll pair 207 located downstream of the first midstream draw roll pair 371 along the draw path 353 and upstream of the first downstream draw roll pair 389 along the draw path 353. In another example, the intermediate draw roll apparatus 405 can optionally be provided with a second intermediate draw roll pair 415 located downstream of the second midstream draw roll pair 379 along the draw path 353 and upstream of the second downstream draw roll pair 397 along the draw path 353.

[0179] The method also includes a step of forming the glass ribbon 121 having a width "W" extending between the first edge portion 105a and the second edge portion 121b. For example, the first puller roll apparatus 349 can be independently operated with no input from the second puller roll apparatus 369 or the third puller roll apparatus 387, or, when provided, the intermediate puller roll apparatus 405. For example, the first puller roll apparatus 349 can be independently operated such that at least one draw roll (puller roll element 355a, 355b) of the first upstream draw roll pair 351 is rotated at a substantially constant torque to draw the first edge portion 121a of the glass ribbon 121 along the draw path 353. In one example, the first puller roll apparatus 349 can be operated such that both draw rolls (puller roll elements 355a, 355b) of the first upstream draw roll pair 351 are rotated at a substantially constant torque.

[0180] The second upstream draw roll pair 361, if provided, can also be independently operated such that at least one draw roll (puller roll element 363a, 363b) of the second upstream draw roll pair 361 is rotated at a substantially constant torque to draw the second edge portion 121b of the glass ribbon 121 along the draw path 353. In one example, the first puller roll apparatus 349 can be operated such that both draw rolls (puller roll elements 363a, 363b) of the second upstream draw roll pair 361 are rotated at a substantially constant torque. In this manner, a desired tension 439 can be maintained in the glass ribbon 121 between the root 70 and the first puller roll apparatus 349 along the draw path 353.

[0181] The method also independently operates the second puller roll apparatus 369 such that at least one draw roll (puller roll element 373a, 373b) of the first midstream draw roll pair 371 is rotated at a substantially constant torque to further draw the first edge portion 121a of the glass ribbon 121 along the draw path 353. In one example, the method can include a step of operating the second puller roll apparatus 369 such that both draw rolls (puller roll elements 373a, 373b) of the first midstream draw roll pair 371 are rotated at a substantially constant torque.

[0182] The second midstream draw roll pair 379 (if provided) can also be independently operated such that at least one draw roll (pull roll element 381a, 381b) of the second midstream draw roll pair 379 is rotated with a substantially constant torque to draw the second edge portion 121b of the glass ribbon 121 along the draw path 353. In one example, the second pull roll apparatus 369 can be operated such that both draw rolls (pull roll elements 381a, 381b) of the second midstream draw roll pair 379 are rotated with a substantially constant torque. In this manner, a desired tension 441 can be maintained in the glass ribbon 121 between the first pull roll apparatus 349 and the second pull roll apparatus 369 along the draw path 353.

[0183] The method can also independently operate the third pull roll apparatus 387 such that at least one draw roll (pull roll element 391a, 391b) of the first downstream draw roll pair 389 is rotated with a substantially constant angular velocity to further draw the first edge portion 121a of the glass ribbon 121 along the draw path 353. In one example, the method can include the step of operating the third pull roll apparatus 387 such that both draw rolls (pull roll elements 391a, 391b) of the first downstream draw roll pair 389 are rotated with a substantially constant angular velocity.

[0184] The second downstream draw roll pair 397 (if provided) can also be independently operated such that at least one draw roll (pull roll element 399a, 399b) of the second downstream draw roll pair 397 is rotated with a substantially constant angular velocity to draw the second edge portion 121b of the glass ribbon 121 along the draw path 353. In one example, the method can include the step of operating the third pull roll apparatus 387 such that both draw rolls (pull roll elements 399a, 399b) of the second downstream draw roll pair 397 are rotated with a substantially constant angular velocity. In this manner, a desired tension 443 can be maintained in the glass ribbon 121 between the second pull roll apparatus 369 and the third pull roll apparatus 387 along the draw path 353.

[0185] When provided, the method can also independently operate the intermediate pull roll apparatus 405 such that at least one draw roll (pull roll element 409a, 409b) of the first intermediate draw roll pair 407 is rotated with a substantially constant torque to further draw the first edge portion 121a of the glass ribbon 121 along the draw path 353. Figure 18 and 19 In one example, the method can include the step of operating the intermediate pull roll apparatus 405 such that both draw rolls (pull roll elements 409a, 409b) of the first intermediate draw roll pair 407 are rotated with a substantially constant torque.

[0186] The second intermediate draw roll pair 415, if provided, can also be independently operated such that at least one draw roll (pull roll element 417a, 417b) of the second intermediate draw roll pair 415 is rotated with a substantially constant torque to further draw the second edge portion 121b of the glass ribbon 121 along the draw path 353. In one example, the method can include the step of operating the intermediate pull roll apparatus 405 such that both draw rolls (pull roll elements 417a, 417b) of the second intermediate draw roll pair 415 are rotated with a substantially constant torque. In this manner, the desired tension 445 in the glass ribbon 121 between the second pull roll apparatus 169 and the intermediate pull roll apparatus 405 along the draw path 353 can be maintained, and the desired tension 447 in the glass ribbon 121 between the intermediate pull roll apparatus 405 and the third pull roll apparatus 387 along the draw path 353 can be maintained.

[0187] Although the exemplary embodiments describe the first pull roll apparatus 349 operating in a constant torque mode, the second pull roll apparatus 369 operating in a constant torque mode, the third pull roll apparatus 387 operating in a constant angular velocity mode, and the intermediate pull roll apparatus 405 operating in a constant torque mode, the present disclosure is not limited thereto. That is, each pull roll apparatus can operate in either a constant torque mode or a constant angular velocity mode. For example, the pull roll apparatuses can operate in the control schemes of Table 1. For example, the first pull roll apparatus 349 can operate in a constant torque mode, the second pull roll apparatus 369 can operate in a constant angular velocity mode, the third pull roll apparatus 387 can operate in a constant angular velocity mode, and, if provided, the intermediate pull roll apparatus 405 can operate in a constant angular velocity mode, such as control scheme "C" of Table 1.

[0188] The method can also include the step of sequentially separating a plurality of glass sheets 347a, 347b from the glass ribbon 121 at a location along the draw path 353 downstream of the first downstream draw roll pair 389 over a period of time. For example, as shown in FIG. 3, the separation apparatus 319 can be periodically activated to sequentially separate a plurality of glass sheets 347a, 347b from the glass ribbon 121 as the glass ribbon 121 is drawn from the forming vessel 60. Figure 13 and 14 The separation apparatus 319 can be periodically activated to sequentially separate a plurality of glass sheets 347a, 347b from the glass ribbon 121 as the glass ribbon 121 is drawn from the forming vessel 60.

[0189] Figure 20 showing a constant force at the first pull roll apparatus 349 in the viscous region 341 of Figure 13 and curve 451 showing a constant force at the third pull roll apparatus 387 in the viscous region 341 of Figure 13The second pull roll apparatus 369 is located in the solidification (viscoelastic) zone 343. The user can configure the control device 423 to operate the first and second pull roll apparatuses 349, 369 independently with constant force over time. Thus, the glass ribbon 121 experiences a constant longitudinal force from the root 70 to the lowermost roll (third pull roll apparatus 387).

[0190] As shown in FIG. 3, the first and second pull roll apparatuses 349, 369 are located in the solidification (viscoelastic) zone 343. The user can configure the control device 423 to operate the first and second pull roll apparatuses 349, 369 independently with constant force over time. Thus, the glass ribbon 121 experiences a constant longitudinal force from the root 70 to the lowermost roll (third pull roll apparatus 387). Figure 13 As shown in FIG. 3, the first and second pull roll apparatuses 349, 369 are located in the solidification (viscoelastic) zone 343. The user can configure the control device 423 to operate the first and second pull roll apparatuses 349, 369 independently with constant force over time. Thus, the glass ribbon 121 experiences a constant longitudinal force from the root 70 to the lowermost roll (third pull roll apparatus 387).

[0191] Figure 21 An example plot of the force applied to the glass ribbon 121 by the first and second downstream draw roll pairs 389, 397 is shown. The Y-axis is force (lbs), and the X-axis is time (hours:minutes). One plot 453 represents the force applied to the glass ribbon 121 by the first downstream draw roll pair 389 at the first edge portion 121a, and another plot 455 represents the force applied to the glass ribbon 121 by the second downstream draw roll pair 397 at the second edge portion 121b. The force plots show a sawtooth pattern associated with the gradual change in the weight of the glass ribbon 121 due to the growth and sudden change in the weight of the glass ribbon 121 caused by the sudden break of the glass sheet 347a from the glass ribbon 121. Since the third pull roll apparatus 387 is located downstream of the viscoelastic zone 343, as described by the viscosity equation (Equation 1), the force applied to the glass ribbon 121 by the third pull roll apparatus 387 is constant over time. Figure 13 As shown in FIG. 3, the first and second pull roll apparatuses 349, 369 are located in the solidification (viscoelastic) zone 343. The user can configure the control device 423 to operate the first and second pull roll apparatuses 349, 369 independently with constant force over time. Thus, the glass ribbon 121 experiences a constant longitudinal force from the root 70 to the lowermost roll (third pull roll apparatus 387).

[0192] η(T) / G = 10000 seconds [Equation 1]

[0193] where the units of viscosity (η) are Pa.s, and the units of shear modulus (G) are Pa. Thus, the units of η / G are time.

[0194] As shown in FIG. 3, the first and second pull roll apparatuses 349, 369 are located in the solidification (viscoelastic) zone 343. The user can configure the control device 423 to operate the first and second pull roll apparatuses 349, 369 independently with constant force over time. Thus, the glass ribbon 121 experiences a constant longitudinal force from the root 70 to the lowermost roll (third pull roll apparatus 387). Figure 20 and 21 As shown in FIG. 3, the first and second pull roll apparatuses 349, 369 are located in the solidification (viscoelastic) zone 343. The user can configure the control device 423 to operate the first and second pull roll apparatuses 349, 369 independently with constant force over time. Thus, the glass ribbon 121 experiences a constant longitudinal force from the root 70 to the lowermost roll (third pull roll apparatus 387).

[0195] Figure 22The speed versus time (hours:minutes) of the first and second downstream drawing roller pairs 389, 397 of the third drawing roller device 387 (which is either the lowest drawing roller device or the active drawing roller device) is shown, and the constant speed (0.2 inches / minute (50.8 mm / minute) per scale division) is shown to control the thickness of the glass ribbon 121 and maintain excellent properties. This speed can be easily adjusted by the control device 423 to obtain the desired product specifications, such as thickness.

[0196] like Figure 13 As shown, the glass strip 121 is drawn along the drawing path 353 in the drawing direction 457. Return to... Figure 20 , 21 Throughout the time period, the first and second upstream drawing roller pairs 351 and 361 apply substantially constant forces (e.g., 8 pounds) to the corresponding first and second edge portions 121a and 121b of the glass strip 121 in directions opposite to the drawing direction 457. Throughout the time period, the first and second midstream drawing roller pairs 371 and 379 also apply substantially constant forces (e.g., 6 pounds) to the corresponding first and second edge portions 121a and 121b of the glass strip 121 in directions opposite to the drawing direction 457. As further shown, the first and second downstream drawing roller pairs 389 and 397 apply varying forces to the corresponding first and second edge portions 121a and 121b of the glass strip 121 in directions ranging from the drawing direction 457 (e.g., approximately 5 pounds) to the direction opposite to the drawing direction 457 (e.g., approximately 18 pounds). Thus, throughout the entire time period, the first edge portion 121a is kept under constant tension between the first upstream pulling roller pair 351, the first midstream pulling roller pair 371, and the first downstream pulling roller pair 389. Similarly, throughout the entire time period, the second edge portion 121b is kept under constant tension between the second upstream pulling roller pair 361, the second midstream pulling roller pair 379, and the second downstream pulling roller pair 397. In other examples, depending on the equipment settings, all forces acting on the two edges 121a, 121b can act in either a positive or negative direction relative to the pulling direction 457.

[0197] like Figure 21Further shown, due to the constant angular velocity associated with the first and second downstream draw rolls 389, 397, the first and second downstream draw roll pairs 389, 397 exert varying forces on the glass ribbon 121. The patterns 459, 461 of tiles 453, 455 represent the varying forces as the length of the glass ribbon 121 increases, while the patterns 463, 465 represent the sudden changes in force that occur during the process of separating the glass sheets 347a from the glass ribbon 121. During the same time period, the constant torque of the first and second upstream draw roll pairs 351, 361 can maintain a substantially constant force on the glass ribbon 121, while the constant torque of the first and second midstream draw roll pairs 371, 379 can also maintain a substantially constant force on the glass ribbon 121. In this way, force perturbations can be prevented from propagating upstream along the glass ribbon into the solidification zone 343, where stress concentrations and corresponding surface defects can be undesirably frozen into the glass ribbon 121.

[0198] In this way, the method of the present disclosure can independently operate the first pull roll apparatus 349 over time such that the first upstream draw roll pair 351 exerts a substantially constant force on the first edge portion 121a of the glass ribbon 121 along the draw path 353. The method can also include the step of independently operating the second pull roll apparatus 369 over time such that at least one of the first downstream draw roll pair 371 exerts a substantially constant force on the first edge portion 121a of the glass ribbon 121 along the draw path 353. The method can also include the step of independently operating the third pull roll apparatus 387 over time such that at least one of the first downstream draw roll pair 389 rotates at a substantially constant angular velocity and the first downstream draw roll pair 389 exerts a varying force on the first edge portion 121a of the glass ribbon 121 along the draw path 353. The method can also include the step of sequentially separating a plurality of glass sheets 347a from the glass ribbon 121 over a period of time at a location along the draw path 353 downstream of the first downstream draw roll pair 389.

[0199] As described above, the first pull roll apparatus 349 can be provided with a second upstream draw roll pair 361. In such examples, the method can further include the step of operating the first pull roll apparatus 349 such that the second upstream draw roll pair 361 exerts a substantially constant force along the draw path 353 against the second edge portion 121b of the glass ribbon 121. As described above, the second pull roll apparatus 369 can include a second midstream draw roll pair 379 located downstream of the second upstream draw roll pair 361 along the draw path 353. The method can further include the step of operating the second pull roll apparatus 369 such that the second midstream draw roll pair 379 exerts a substantially constant force along the draw path 353 against the second edge portion 121b of the glass ribbon 121. As further described above, the third pull roll apparatus 387 can include a second downstream draw roll pair 397 located downstream of the second midstream draw roll pair 379 along the draw path 353. In such examples, the method can further include the step of operating the third pull roll apparatus 387 such that at least one of the second downstream draw roll pair 397 rotates at a substantially constant angular velocity and the second downstream draw roll pair 397 exerts a varying force along the draw path 353 against the second edge portion 121b of the glass ribbon 121.

[0200] The method can further include the step of independently operating the intermediate pull roll apparatus 405 (if provided) over time such that at least one of the first intermediate draw roll pair 407 exerts a substantially constant force along the draw path 353 against the first edge portion 121a of the glass ribbon 121. As described above, the intermediate pull roll apparatus 405 can be provided with a second intermediate draw roll pair 415. In such examples, the method can further include the step of operating the intermediate pull roll apparatus 405 such that the second intermediate draw roll pair 415 exerts a substantially constant force along the draw path 353 against the second edge portion 121b of the glass ribbon 121.

[0201] The pull roll apparatus 315 can be used to improve the consistency of the lateral draw tension and / or down-web tension in the glass ribbon, which reduces residual stresses on the manufactured glass ribbon and improves the glass flatness. More specifically, the pull roll apparatus 315 can be used to control and improve the consistency of the lateral draw tension and / or down-web tension in the area of the glass ribbon passing through the solidification zone, in which product stresses and flatness are solidified into the glass ribbon.

[0202] In a comparative example embodiment, a pull roll apparatus can have only an upper draw roll apparatus and a lower draw roll apparatus. In such a comparative pull roll apparatus, the required constant torque or constant speed pinch force at the upper and lower pull roll apparatuses can be too large for a large weight glass ribbon, such that the pinch force between the draw roll pairs can cause the glass ribbon to crack. A large weight glass ribbon can exist when manufacturing large glass sheets of large width and length and small thickness.

[0203] Furthermore, operating the upstream draw roll pair, the midstream draw roll pair, and the intermediate draw roll pair, if provided, in a substantially constant torque mode as described by the exemplary embodiments of the present disclosure and as shown in FIGS. 449, 451 provides other advantages over operating the upstream draw roll pair and the midstream draw roll pair at a substantially constant angular velocity. First, the constant angular velocity of the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, can provide different tensions at different diameters in the rolls. In contrast, operating the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, at a substantially constant torque enables a consistent vertical tension over time. In fact, operating at a substantially constant torque almost compensates for the wear of the rolls. For constant torque, as the rolls wear, the force changes slightly with the roll diameter, but the impact is very small. Speed control has a much higher sensitivity to the roll diameter. Second, it can be demonstrated that it is difficult to correlate the constant angular velocity of the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, to the web speed due to the uncertainty of the diameter of the rolls. In contrast, operating the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, at a substantially constant torque removes the need to correlate to get the proper angular velocity of the rolls. A third point, operating the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, at a substantially constant torque can avoid the risk of kinking or cracking that can occur when trying to adjust the speed of the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, to compensate for roll wear. A fourth, operating the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, at a substantially constant torque can avoid the risk of roll skipping if the constant angular velocity is too low. A fifth point, operating the upstream and midstream draw roll pairs and the intermediate draw roll pair, if provided, can avoid excessive pull force variations that can result from the rolls running in a constant angular velocity mode.

[0204] Accordingly, exemplary embodiments of the present disclosure enable an increase in the pull force on the glass ribbon due to the use of multiple elevation drive rolls. As a result, larger, heavier, and thinner sheets with flatter surfaces can be made. Exemplary embodiments of the present disclosure enable a modular design that can be easily extended to four or more elevations. Exemplary embodiments of the present disclosure enable the placement of drive rolls at the desired elevations to provide the longitudinal and transverse draw forces needed to maintain a flat glass ribbon through the viscoelastic region. As a result, longer and wider viscoelastic regions can be achieved. Exemplary embodiments of the present disclosure enable the lowest roll to be placed below the viscoelastic region to maintain a constant longitudinal force through the viscoelastic region from the root and to isolate the viscoelastic region from disturbances from downstream, e.g., disturbances such as the effects of ribbon growth and the sudden breaking of the ribbon into sheets.

[0205] Some of the functional units described in this specification, such as the control device, are labeled as modules to emphasize their implementation independence. For example, a module can be implemented as a hardware circuit comprising custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, or programmable logic devices. Modules can also be implemented in software for execution by various types of processors. An identified module of executable code can, for instance, comprise one or more physical or logical blocks of computer instructions which can, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but can comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.

[0206] Modules of executable code can also be a single instruction, or many instructions, and can even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data can be identified and illustrated herein within modules, and can be embodied in any suitable form and organized within any suitable type of data structure. The operational data can be collected as a single data set, or can be distributed over different locations including over different storage devices, and can exist, at least partially, merely as electronic signals on a system or network.

[0207] Modules of executable code can be a single instruction, or many instructions, and even can be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data can be identified and illustrated herein within modules, and can be embodied in any suitable form and organized within any suitable type of data structure. The operational data can be collected as a single data set, or can be distributed over different locations including over different storage devices, and can exist, at least partially, merely as electronic signals on a system or network.

[0208] Glass composition

[0209] Alkali aluminosilicate glasses have good ion exchangeability and high strength and high toughness properties have been achieved in alkali aluminosilicate glasses using a chemical strengthening process. Alkali aluminosilicate glasses are highly ion exchangeable glasses with high glass formability and quality. Substitution of AI2O3into the silicate glass network increases the interdiffusion coefficient of monovalent cations during ion exchange. Glasses with high strength, high toughness, and high indentation crack resistance can be achieved through chemical strengthening in a molten salt bath (e.g., KNO3or NaNO3).

[0210] Accordingly, alkali aluminosilicate glasses having good physical properties, chemical durability, and ion exchangeability have attracted attention for use as cover glasses and / or as part of consumer electronic devices. In particular, provided herein are lithium-containing aluminosilicate glasses having a relatively low annealing temperature and softening temperature, a relatively low coefficient of thermal expansion (CTE) value, and fast ion exchangeability. Greater central tension (CT), depth of compression (DOC), and high compressive stress (CS) can be achieved through different ion exchange processes. However, the addition of lithium in alkali aluminosilicate glasses can lower the melting point or softening point of the glass. Accordingly, provided herein is a balance of various glass components that allows the glass to achieve the benefits of adding lithium to the glass composition without negatively impacting the glass composition.

[0211] In embodiments of the glass compositions described herein, the concentration of a constituent component (e.g., Si02, AI2O3, and Li02, etc.) is in mole percent (mol%) on an oxide basis, unless otherwise specified. The components of the Li-containing aluminosilicate glass compositions according to embodiments are discussed individually below. It should be understood that any of the various stated ranges for one component can be combined with any of the various stated ranges for any other component, individually.

[0212] In exemplary Li-containing aluminosilicate glass compositions, Si02is the most predominant component, whereby Si02is the primary component of the glass network formed from the glass composition. Pure Si02has a low CTE and is alkali-free. However, pure Si02has a high melting point. Accordingly, if the concentration of Si02in the glass composition is too high, the formability of the glass composition can decrease because a higher Si02concentration increases the difficulty of melting the glass, which in turn negatively impacts the formability of the glass. In embodiments, the glass composition generally comprises Si02in an amount of greater than or equal to 60 mol% to less than or equal to 74 mol%, and all ranges and sub-ranges therebetween. In some embodiments, the glass composition comprises Si02in an amount of greater than or equal to 62 mol%, greater than or equal to 64 mol%, greater than or equal to 66 mol%, greater than or equal to 68 mol%, greater than or equal to 70 mol%, or greater than or equal to 72 mol%. In some embodiments, the glass composition comprises Si02in an amount of less than or equal to 72 mol%, less than or equal to 70 mol%, less than or equal to 68 mol%, less than or equal to 66 mol%, less than or equal to 64 mol%, or less than or equal to 62 mol%. In other embodiments, the glass composition comprises Si02in an amount of greater than or equal to 60 mol% to less than or equal to 66 mol%, or greater than or equal to 65 mol% to less than or equal to 74 mol%, or greater than or equal to 66 mol% to less than or equal to 70 mol%, and all ranges and sub-ranges therebetween.

[0213] The glass compositions of the embodiments can also include AI2O3. Similar to SiO2, AI2O3 can have the role of a glass network former. AI2O3 can increase the viscosity of the glass composition because it is tetrahedrally coordinated in the glass melt formed from a properly designed glass composition, which reduces the formability of the glass composition when the amount of AI2O3 is too high. However, when the concentration of AI2O3 is balanced with the concentration of SiO2 and the concentration of alkali oxides in the glass composition, AI2O3 can lower the liquidus temperature of the glass melt, thereby enhancing the liquidus viscosity and improving the compatibility of the glass composition with certain forming processes, such as fusion forming processes. In embodiments, the glass composition generally includes AI2O3 in an amount of greater than or equal to 7 mol% to less than or equal to 18 mol%, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition generally includes AI2O3 in an amount of greater than or equal to 8 mol%, greater than or equal to 9 mol%, greater than or equal to 10 mol%, greater than or equal to 11 mol%, greater than or equal to 12 mol%, greater than or equal to 13 mol%, greater than or equal to 14 mol%, greater than or equal to 15 mol%, greater than or equal to 16 mol%, or greater than or equal to 17 mol%. In some embodiments, the glass composition includes AI2O3 in an amount of less than or equal to 18 mol%, less than or equal to 17 mol%, less than or equal to 16 mol%, less than or equal to 15 mol%, less than or equal to 14 mol%, less than or equal to 13 mol%, less than or equal to 12 mol%, less than or equal to 11 mol%, less than or equal to 10 mol%, less than or equal to 9 mol%, or less than or equal to 8 mol%. In other embodiments, the glass composition includes AI2O3 in an amount of greater than or equal to 8 mol% to less than or equal to 17 mol%, such as greater than or equal to 9 mol% to less than or equal to 16 mol%, greater than or equal to 10 mol% to less than or equal to 15 mol%, or greater than or equal to 11 mol% to less than or equal to 14 mol%, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition includes AI2O3 in an amount of greater than or equal to 11.5 mol% to less than or equal to 18 mol%, or greater than or equal to 7 mol% to less than or equal to 12 mol%, and all ranges and sub-ranges between the foregoing values.

[0214] Similar to Si02and AI2O3, P2O5may be added to the glass composition as a network former, thereby reducing the meltable and formable properties of the glass composition. Accordingly, the amount of P2O5added can be such that these properties are not excessively reduced. In embodiments, the glass composition can include P2O5in an amount greater than or equal to 0 mol% to less than or equal to 5 mol%, and all ranges and sub-ranges therebetween. In some embodiments, the glass composition can include P2O5in an amount greater than or equal to 0.5 mol%, greater than or equal to 1 mol%, greater than or equal to 1.5 mol%, greater than or equal to 2 mol%, greater than or equal to 2.5 mol%, greater than or equal to 3 mol%, greater than or equal to 3.5 mol%, greater than or equal to 4 mol%, or greater than or equal to 4.5 mol%. In other embodiments, the glass composition can include P2O5in an amount less than or equal to 5 mol%, less than or equal to 4.5 mol%, less than or equal to 4 mol%, less than or equal to 3.5 mol%, less than or equal to 3 mol%, less than or equal to 2.5 mol%, less than or equal to 2 mol%, less than or equal to 1.5 mol%, less than or equal to 1 mol%, or less than or equal to 0.5 mol%. In other embodiments, the glass composition can include P2O5in an amount greater than or equal to 0.5 mol% to less than or equal to 4.5 mol%, greater than or equal to 1 mol% to less than or equal to 4 mol%, greater than or equal to 1.5 mol% to less than or equal to 3.5 mol%, or greater than or equal to 2 mol% to less than or equal to 3 mol%, and all ranges and sub-ranges therebetween.

[0215] Similar to Si02, AI2O3, and P2O5, B2O3 can be added to the glass composition as a network former, thereby reducing the meltability and formability of the glass composition. Thus, the amount of B2O3 added can be without undue reduction of these properties. In embodiments, the glass composition comprises B2O3 in an amount of: greater than or equal to 3 mol% B2O3to less than or equal to 16 mol% B2O3, and all ranges and sub-ranges therebetween. In some embodiments, the glass composition comprises B2O3 in an amount of: greater than or equal to 3.5 mol%, greater than or equal to 4 mol%, greater than or equal to 4.5 mol%, greater than or equal to 5 mol%, greater than or equal to 5.5 mol%, greater than or equal to 6 mol%, greater than or equal to 6.5 mol%, greater than or equal to 7 mol%, greater than or equal to 7.5 mol%, greater than or equal to 8 mol%, greater than or equal to 8.5 mol%, greater than or equal to 9 mol%, greater than or equal to 9.5 mol%, greater than or equal to 10 mol%, greater than or equal to 10.5 mol%, greater than or equal to 11 mol%, greater than or equal to 11.5 mol%, greater than or equal to 12 mol%, greater than or equal to 12.5 mol%, greater than or equal to 13 mol%, greater than or equal to 13.5 mol%, greater than or equal to 14 mol%, greater than or equal to 14.5 mol%, greater than or equal to 15 mol%, or greater than or equal to 15.5 mol%. In other embodiments, the glass composition comprises B2O3 in an amount of: less than or equal to 15.5 mol%, less than or equal to 15 mol%, less than or equal to 14.5 mol%, less than or equal to 14 mol%, less than or equal to 13.5 mol%, less than or equal to 13 mol%, less than or equal to 12.5 mol%, less than or equal to 12 mol%, less than or equal to 11.5 mol%, less than or equal to 11 mol%, less than or equal to 10.5 mol%, less than or equal to 10 mol%, less than or equal to 9.5 mol%, less than or equal to 9 mol%, less than or equal to 8.5 mol%, less than or equal to 8 mol%, less than or equal to 7.5 mol%, less than or equal to 7 mol%, less than or equal to 6.5 mol%, less than or equal to 6 mol%, less than or equal to 5.5 mol%, less than or equal to 5 mol%, less than or equal to 4.5 mol%, less than or equal to 4 mol%, or less than or equal to 3.5 mol%.In other embodiments, the glass composition can comprise B2O3 in an amount of: greater than or equal to 3.5 mol.% to less than or equal to 15.5 mol.%, greater than or equal to 4 mol.% to less than or equal to 15 mol.%, greater than or equal to 4.5 mol.% to less than or equal to 14.5 mol.%, greater than or equal to 5 mol.% to less than or equal to 14 mol.%, greater than or equal to 5.5 mol.% to less than or equal to 13.5 mol.%, greater than or equal to 6 mol.% to less than or equal to 13 mol.%, greater than or equal to 6.5 mol.% to less than or equal to 12.5 mol.%, greater than or equal to 7 mol.% to less than or equal to 12 mol.%, greater than or equal to 7.5 mol.% to less than or equal to 11.5 mol.%, greater than or equal to 8 mol.% to less than or equal to 11 mol.%, greater than or equal to 8.5 mol.% to less than or equal to 10.5 mol.%, greater than or equal to 9 mol.% to less than or equal to 10 mol.%, greater than or equal to 3 mol.% to less than or equal to 8 mol.%, greater than or equal to 5 mol.% to less than or equal to 16 mol.%, and all ranges and sub-ranges between the foregoing values.

[0216] The role of Li2O in the glass composition is discussed above and is further discussed in detail below. In part, the addition of lithium in the glass enables better control over the ion exchange process and further reduces the softening point of the glass. In embodiments, the glass composition generally comprises Li2O in an amount of: greater than or equal to 5 mol.% to less than or equal to 11 mol.%, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises Li2O in an amount of: greater than or equal to 5.5 mol.%, greater than or equal to 6 mol.%, greater than or equal to 6.5 mol.%, greater than or equal to 7 mol.%, greater than or equal to 7.5 mol.%, greater than or equal to 8 mol.%, greater than or equal to 8.5 mol.%, greater than or equal to 9 mol.%, greater than or equal to 9.5 mol.%, greater than or equal to 10 mol.%, or greater than or equal to 10.5 mol.%. In some embodiments, the glass composition comprises Li2O in an amount of: less than or equal to 10.5 mol.%, less than or equal to 10 mol.%, less than or equal to 9.5 mol.%, less than or equal to 9 mol.%, less than or equal to 8.5 mol.%, less than or equal to 8 mol.%, less than or equal to 7.5 mol.%, less than or equal to 7 mol.%, less than or equal to 6.5 mol.%, less than or equal to 6 mol.%, or less than or equal to 5.5 mol.%. In other embodiments, the glass composition comprises Li2O in an amount of: greater than or equal to 5.5 mol.% to less than or equal to 10.5 mol.%, for example: greater than or equal to 6 mol.% to less than or equal to 10 mol.%, greater than or equal to 6.5 mol.% to less than or equal to 9.5 mol.%, greater than or equal to 7 mol.% to less than or equal to 9 mol.%, or greater than or equal to 7.5 mol.% to less than or equal to 8.5 mol.%, and all ranges and sub-ranges between the foregoing values.

[0217] According to embodiments, the glass composition can also include alkali oxides other than Li20, such as Na20 and K20. Na20 contributes to the ion-exchangeability of the glass composition and also increases the melting point of the glass composition and improves the formability of the glass composition. However, if too much Na20 is added to the glass composition, the coefficient of thermal expansion (CTE) can be too low and the melting point can be too high. In embodiments, the glass composition generally includes Na20 in an amount of greater than 0 mole% to less than or equal to 6 mole%, or greater than or equal to 0 mole% to less than or equal to 6 mole%, and all ranges and sub-ranges therebetween. In some embodiments, the glass composition includes Na20 in an amount of greater than or equal to 0.5 mole%, greater than or equal to 1 mole%, greater than or equal to 1.5 mole%, greater than or equal to 2 mole%, greater than or equal to 2.5 mole%, greater than or equal to 3 mole%, greater than or equal to 3.5 mole%, greater than or equal to 4 mole%, greater than or equal to 4.5 mole%, greater than or equal to 5 mole%, greater than or equal to 5.5 mole%. In some embodiments, the glass composition includes Na20 in an amount of less than or equal to 5.5 mole%, less than or equal to 5 mole%, less than or equal to 4.5 mole%, less than or equal to 4 mole%, less than or equal to 3.5 mole%, less than or equal to 3 mole%, less than or equal to 2.5 mole%, less than or equal to 2 mole%, less than or equal to 1.5 mole%, less than or equal to 1 mole%, or less than or equal to 0.5 mole%. In other embodiments, the glass composition includes Na20 in an amount of greater than or equal to 0.5 mole% to less than or equal to 5.5 mole%, such as greater than or equal to 1 mole% to less than or equal to 5 mole%, greater than or equal to 1.5 mole% to less than or equal to 4.5 mole%, greater than or equal to 2 mole% to less than or equal to 4 mole%, or greater than or equal to 2.5 mole% to less than or equal to 3.5 mole%, greater than or equal to 2 mole% to less than or equal to 6 mole%, greater than or equal to 0 mole% to less than or equal to 4 mole%, and all ranges and sub-ranges therebetween.

[0218] Similar to Na20, K20 also promotes ion-exchange and increases the DOC of the compressive stress layer. However, the CTE can be too low and the melting point can be too high. In embodiments, the glass composition is essentially free of potassium. As used herein, the term "essentially free" means that the component is not added as a component of the batch materials, although very small amounts of the component (e.g., less than 0.1 mole%) can be present in the final glass as a contaminant. In other embodiments, the glass composition can include K20 in an amount of less than 1 mole%.

[0219] MgO reduces the viscosity of the glass, which enhances formability, strain point, and Young’s modulus, and can improve ion exchange capability. However, when the glass composition is added with too much MgO, the density and CTE of the glass composition increase. In embodiments, the glass composition generally comprises a concentration of MgO of greater than or equal to 0 mol% to less than or equal to 6.5 mol%, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition comprises MgO in an amount of greater than or equal to 0.5 mol%, greater than or equal to 1 mol%, greater than or equal to 1.5 mol%, greater than or equal to 2 mol%, greater than or equal to 2.5 mol%, greater than or equal to 3 mol%, greater than or equal to 3.5 mol%, greater than or equal to 4 mol%, greater than or equal to 4.5 mol%, greater than or equal to 5 mol%, greater than or equal to 5.5 mol%, or greater than or equal to 6 mol%. In some embodiments, the glass composition comprises MgO in an amount of less than or equal to 6 mol%, less than or equal to 5.5 mol%, less than or equal to 5 mol%, less than or equal to 4.5 mol%, less than or equal to 4 mol%, less than or equal to 3.5 mol%, less than or equal to 3 mol%, less than or equal to 2.5 mol%, less than or equal to 2 mol%, less than or equal to 1.5 mol%, or less than or equal to 1 mol%. In other embodiments, the glass composition comprises MgO in an amount of greater than or equal to 0.5 mol% to less than or equal to 6 mol%, for example, greater than or equal to 1 mol% to less than or equal to 5.5 mol%, greater than or equal to 1.5 mol% to less than or equal to 5 mol%, greater than or equal to 2 mol% to less than or equal to 4.5 mol%, greater than or equal to 2.5 mol% to less than or equal to 4 mol%, or greater than or equal to 3 mol% to less than or equal to 3.5 mol%, and all ranges and sub-ranges between the foregoing values.

[0220] CaO reduces the viscosity of glass, which enhances formability, strain point, and Young's modulus, and can improve ion exchange capacity. However, when too much CaO is added to the glass composition, the density and CTE of the glass composition increase. In embodiments, the glass composition typically contains CaO concentrations ranging from 0 mol% to 5 mol%, and all ranges and subranges between these values. In some embodiments, the glass composition contains CaO amounts of 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol%, 4 mol%, or 4.5 mol%. In some embodiments, the glass composition contains CaO amounts of 4.5 mol%, 4 mol%, 3.5 mol%, 2.5 mol%, 1.5 mol%, or 0.5 mol%. In other embodiments, the amount of CaO contained in the glass composition is: greater than or equal to 0.5 mol% to less than or equal to 4.5 mol%, for example: greater than or equal to 1 mol% to less than or equal to 4 mol%, greater than or equal to 1.5 mol% to less than or equal to 3 mol%, or greater than or equal to 2 mol% to less than or equal to 3 mol%, and all ranges and subranges between the above values.

[0221] In embodiments, the glass composition may optionally contain one or more clarifying agents. In some embodiments, the clarifying agent may include, for example, SnO2. In such embodiments, the amount of SnO2 present in the glass composition may be less than or equal to 0.2 mol%, for example, greater than or equal to 0 mol% to less than or equal to 0.11 mol%, and all ranges and subranges between the above values. In other embodiments, the amount of SnO2 present in the glass composition may be greater than or equal to 0 mol% to less than or equal to 0.2 mol%, or greater than or equal to 0.1 mol% to less than or equal to 0.2 mol%, and all ranges and subranges between the above values.

[0222] ZnO enhances the ion exchange performance of the glass by, for example, increasing the compressive stress of the glass. However, too much ZnO can increase the density and cause phase separation. In embodiments, the glass composition can include ZnO in an amount greater than or equal to 0 mol% to less than or equal to 2 mol%, such as greater than or equal to 0.5 mol% to less than or equal to 1.5 mol%, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition can include ZnO in an amount greater than or equal to 0.5 mol%, greater than or equal to 1 mol%, or greater than or equal to 1.5 mol%. In other embodiments, the glass composition can include ZnO in an amount less than or equal to 1.5 mol%, less than or equal to 1 mol%, or less than or equal to 0.5 mol%.

[0223] SrO lowers the liquidus temperature of the glass articles disclosed herein. In embodiments, the glass composition can include SrO in an amount greater than or equal to 0.5 mol% to less than or equal to 2 mol%, such as greater than or equal to 1 mol% to less than or equal to 1.5 mol%, and all ranges and sub-ranges between the foregoing values. In some embodiments, the glass composition can include SrO in an amount greater than or equal to 1 mol% or greater than or equal to 1.5 mol%. In other embodiments, the glass composition can include SrO in an amount less than or equal to 1.5 mol%, less than or equal to 1 mol%, or less than or equal to 0.5 mol%.

[0224] In addition to the individual components described above, the glass compositions according to the embodiments disclosed herein can include an amount of trivalent cation oxide that is: greater than or equal to 0.5 mol% to less than or equal to 6.5 mol%, and all ranges and sub-ranges between the foregoing values. As used herein, trivalent cation oxide includes, but is not limited to, Al2O3. In some embodiments, the glass compositions can include an amount of trivalent cation oxide that is: greater than or equal to 1 mol%, greater than or equal to 1.5 mol%, greater than or equal to 2 mol%, greater than or equal to 2.5 mol%, greater than or equal to 3 mol%, greater than or equal to 3.5 mol%, greater than or equal to 4 mol%, greater than or equal to 4.5 mol%, greater than or equal to 5 mol%, greater than or equal to 5.5 mol%, or greater than or equal to 6 mol%. In other embodiments, the glass compositions can include an amount of trivalent cation oxide that is: less than or equal to 5.5 mol%, less than or equal to 5 mol%, less than or equal to 4.5 mol%, less than or equal to 4 mol%, less than or equal to 3.5 mol%, less than or equal to 3 mol%, less than or equal to 2.5 mol%, less than or equal to 2 mol%, less than or equal to 1.5 mol%, or less than or equal to 1 mol%. In other embodiments, the glass compositions can include an amount of trivalent cation oxide that is: greater than or equal to 1 mol% to less than or equal to 6 mol%, greater than or equal to 1.5 mol% to less than or equal to 5.5 mol%, greater than or equal to 2 mol% to less than or equal to 5 mol%, greater than or equal to 2.5 mol% to less than or equal to 4.5 mol%, or greater than or equal to 3.2 mol% to less than or equal to 3 mol%, and all ranges and sub-ranges between the foregoing values.

[0225] In embodiments, the molar ratio of Li20:R20, where R20 is the sum of alkali metal oxides present in the glass composition (e.g., Li20 + Na20 + K20), is greater than or equal to 0.4. Increasing the amount of Li20 in the glass composition increases the CTE and improves the compressive stress profile of the glass article, which can result in improved mechanical properties (e.g., improved damage resistance). Thus, a high proportion of Li20 relative to the other alkali metal oxides (e.g., greater than or equal to 0.4) provides these improvements. In some embodiments, the molar ratio Li20:R20 is: greater than or equal to 0.5, greater than or equal to 0.6, greater than or equal to 0.7, greater than or equal to 0.8, greater than or equal to 0.9, or equal to about 1. In some embodiments, the molar ratio Li20:R20 is: less than or equal to 1, less than or equal to 0.9, less than or equal to 0.8, less than or equal to 0.7, less than or equal to 0.6, or less than or equal to 0.5. In other embodiments, the molar ratio Li20:R20 is: greater than or equal to 0.4 to less than or equal to 1, greater than or equal to 0.5 to less than or equal to 1, greater than or equal to 0.6 to less than or equal to 1, greater than or equal to 0.7 to less than or equal to 1, greater than or equal to 0.8 to less than or equal to 1, or greater than or equal to 0.9 to less than or equal to 1, and all ranges and sub-ranges between the foregoing values. In other embodiments, the molar ratio Li20:R20 is: greater than or equal to 0.4 to less than or equal to 0.9, greater than or equal to 0.4 to less than or equal to 0.8, greater than or equal to 0.4 to less than or equal to 0.7, greater than or equal to 0.4 to less than or equal to 0.6, or greater than or equal to 0.4 to less than or equal to 0.5.

[0226] In embodiments, the molar ratio AI2O3:(R2O + RO) is greater than or equal to 0.9, where RO is the sum of the divalent cation oxides present in the glass composition and R2O is the sum of the alkali metal oxides. Increasing the ratio of AI2O3to R2O + ROimproves the liquidus temperature and viscosity of the glass article. This ratio greater than or equal to 0.9 results in a more dense glass that is less brittle and has higher damage resistance. In some embodiments, the molar ratio AI2O3:(R2O + RO) is: greater than or equal to 1, greater than or equal to 1.1, greater than or equal to 1.2, greater than or equal to 1.3, greater than or equal to 1.4, or equal to 1.5. In other embodiments, the molar ratio AI2O3:(R2O + RO) is: less than or equal to 1.5, less than or equal to 1.4, less than or equal to 1.3, less than or equal to 1.2, less than or equal to 1.1, or less than or equal to 1. In other embodiments, the molar ratio AI2O3:(R2O + RO) is: greater than or equal to 0.9 to less than or equal to 1.5, greater than or equal to 1 to less than or equal to 1.5, greater than or equal to 1.1 to less than or equal to 1.5, greater than or equal to 1.2 to less than or equal to 1.5, greater than or equal to 1.3 to less than or equal to 1.5, or greater than or equal to 1.4 to less than or equal to 1.5, and all ranges and sub-ranges between the foregoing values. In other embodiments, the molar ratio AI2O3:(R2O + RO) is: greater than or equal to 0.9 to less than or equal to 1.4, greater than or equal to 0.9 to less than or equal to 1.3, greater than or equal to 0.9 to less than or equal to 1.2, greater than or equal to 0.9 to less than or equal to 1.1, or greater than or equal to 0.9 to less than or equal to 1, and all ranges and sub-ranges between the foregoing values.

[0227] In embodiments, the total amount of network-forming components Al2O3 + SiO2 + B2O3 + P2O5 is greater than or equal to 80 mole percent, for example: greater than or equal to 82 mole percent, greater than or equal to 84 mole percent, greater than or equal to 86 mole percent, greater than or equal to 88 mole percent, greater than or equal to 90 mole percent, greater than or equal to 92 mole percent, or greater than or equal to 94 mole percent. High amounts of network formers increase the density of the glass, which makes it less brittle, and improves damage resistance. In other embodiments, the total amount of network-forming components is less than or equal to 94 mole percent, less than or equal to 92 mole percent, less than or equal to 90 mole percent, less than or equal to 88 mole percent, less than or equal to 86 mole percent, less than or equal to 84 mole percent, or less than or equal to 82 mole percent. In other embodiments, the total amount of network-forming components is greater than or equal to 80 mole percent to less than or equal to 94 mole percent, greater than or equal to 82 mole percent to less than or equal to 92 mole percent, greater than or equal to 84 mole percent to less than or equal to 90 mole percent, or greater than or equal to 86 mole percent to less than or equal to 88 mole percent, as well as all ranges and sub-ranges between the foregoing values.

[0228] Not limiting to every possible composition selected from the various components described above, in some embodiments, the glass composition may comprise: greater than or equal to 60 mol% to less than or equal to 74 mol% SiO2, greater than or equal to 7 mol% to less than or equal to 18 mol% Al2O3, greater than or equal to 3 mol% to less than or equal to 16 mol% B2O3, greater than or equal to 0 mol% to less than or equal to 6 mol% Na2O, greater than or equal to 0 mol% to less than or equal to 5 mol% P2O5, greater than or equal to 5 mol% to less than or equal to 11 mol% Li2O, less than or equal to 0.2 mol% SnO2, and greater than or equal to 0.5 mol% to less than or equal to 6.5 mol% divalent cationic oxides, wherein the molar ratio Al2O3:(R2O + RO) is greater than or equal to 0.9. In other embodiments, the glass composition may comprise: 60 mol% to 66 mol% SiO2, 11.5 mol% to 18 mol% Al2O3, 3 mol% to 8 mol% B2O3, 2 mol% to 6 mol% Na2O, 0 mol% to 5 mol% P2O5, 5 mol% to 11 mol% Li2O, and 0.5 mol% to 6.5 mol% divalent cationic oxides, wherein the molar ratio Al2O3:(R2O + RO) is greater than or equal to 0.9. In other embodiments, the glass may comprise: 65 mol% to 74 mol% SiO2, 7 mol% to 12 mol% Al2O3, 5 mol% to 16 mol% B2O3, 0 mol% to 4 mol% Na2O, 0 mol% to 5 mol% P2O5, 5 mol% to 11 mol% Li2O, and 0.5 mol% to 6.5 mol% divalent cationic oxides, wherein the molar ratio Al2O3:(R2O + RO) is greater than or equal to 0.9.

[0229] In one embodiment, the glass article may be substantially free of one or both of arsenic and antimony. In other embodiments, the glass article may be free of one or both of arsenic and antimony.

[0230] The physical properties of the Li-containing aluminosilicate glass compositions disclosed above will be discussed below. The properties described below show the results of adding lithium to aluminosilicate glasses or alkali aluminosilicate glasses. These physical properties can be achieved by modifying the component amounts of the Li-containing aluminosilicate glass compositions, which will be discussed in more detail with reference to the examples. The effect of lithium on the physical properties of the glass compositions has not been well understood to date.

[0231] The glass compositions according to embodiments can have a density greater than or equal to 2.20 g / cm3 3 to less than or equal to 2.50 g / cm3 3 , for example, greater than or equal to 2.25 g / cm3 3 to less than or equal to 2.50 g / cm3 3 or greater than or equal to 2.30 g / cm3 3 to less than or equal to 2.50 g / cm3 3 , greater than or equal to 2.35 g / cm3 3 to less than or equal to 2.50 g / cm3 3 , greater than or equal to 2.40 g / cm3 3 to less than or equal to 2.50 g / cm3 3 or greater than or equal to 2.45 g / cm3 3 to less than or equal to 2.50 g / cm3 3 . In other embodiments, the glass compositions can have a density greater than or equal to 2.20 g / cm3 3 to less than or equal to 2.45 g / cm3 3 , greater than or equal to 2.20 g / cm3 3 to less than or equal to 2.40 g / cm3 3 , greater than or equal to 2.20 g / cm3 3 to less than or equal to 2.35 g / cm3 3 , greater than or equal to 2.20 g / cm3 3 to less than or equal to 2.30 g / cm3 3 or greater than or equal to 2.20 g / cm3 3 to less than or equal to 2.25 g / cm3 3 , and all ranges and sub-ranges between the values described above. Generally, in alkali aluminosilicate glass compositions, as larger, denser alkali metal cations (e.g., Na + or K + ) are replaced by smaller alkali metal cations (e.g., Li +Substitution, the density of the glass composition decreases. Thus, the higher the amount of lithium in the glass composition, the less dense the glass composition will be. The density values stated in the present disclosure refer to values measured according to the buoyancy method of ASTM C693-93(2013).

[0232] The strain point, annealing point, and softening point of the glass composition can also be influenced by the amount of lithium in the glass composition. As the amount of lithium in the glass composition increases, the amount of other larger alkali metal cations (e.g., Na + and K + ) decreases. In embodiments, the strain point of the glass composition can be: greater than or equal to 450 °C to less than or equal to 625 °C, such as greater than or equal to 475 °C to less than or equal to 600 °C, greater than or equal to 500 °C to less than or equal to 575 °C, greater than or equal to 515 °C to less than or equal to 560 °C, or greater than or equal to 530 °C to less than or equal to 550 °C, and all ranges and sub-ranges between the foregoing values. In other embodiments, the strain point of the glass composition can be: greater than or equal to 500 °C to less than or equal to 560 °C, such as greater than or equal to 510 °C to less than or equal to 560 °C, greater than or equal to 520 °C to less than or equal to 560 °C, greater than or equal to 530 °C to less than or equal to 560 °C, or greater than or equal to 540 °C to less than or equal to 560 °C. In other embodiments, the strain point of the glass composition can be: greater than or equal to 500 °C to less than or equal to 555 °C, greater than or equal to 500 °C to less than or equal to 550 °C, greater than or equal to 500 °C to less than or equal to 540 °C, greater than or equal to 500 °C to less than or equal to 530 °C, or greater than or equal to 500 °C to less than or equal to 520 °C, and all ranges and sub-ranges between the foregoing values. The strain point values stated in the present disclosure refer to values measured according to the fiber elongation method of ASTM C336-71(2015).

[0233] In embodiments, the glass composition can have an annealing point of greater than or equal to 500 °C to less than or equal to 675 °C, for example, greater than or equal to 525 °C to less than or equal to 650 °C, greater than or equal to 550 °C to less than or equal to 625 °C, greater than or equal to 565 °C to less than or equal to 615 °C, or greater than or equal to 580 °C to less than or equal to 600 °C, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have an annealing point of greater than or equal to 550 °C to less than or equal to 625 °C, for example, greater than or equal to 560 °C to less than or equal to 625 °C, greater than or equal to 570 °C to less than or equal to 625 °C, greater than or equal to 580 °C to less than or equal to 625 °C, or greater than or equal to 590 °C to less than or equal to 625 °C, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have an annealing point of greater than or equal to 550 °C to less than or equal to 615 °C, greater than or equal to 550 °C to less than or equal to 610 °C, greater than or equal to 550 °C to less than or equal to 600 °C, greater than or equal to 550 °C to less than or equal to 590 °C, or greater than or equal to 550 °C to less than or equal to 580 °C, and all ranges and sub-ranges between the foregoing values. The annealing point values stated in this disclosure refer to values measured according to the Fiber Tensile Method of ASTM C336-71 (2015).

[0234] In embodiments, the glass composition can have a softening point of greater than or equal to 725 °C to less than or equal to 950 °C, such as greater than or equal to 750 °C to less than or equal to 925 °C, greater than or equal to 775 °C to less than or equal to 900 °C, greater than or equal to 800 °C to less than or equal to 875 °C, or greater than or equal to 825 °C to less than or equal to 850 °C, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have a softening point of greater than or equal to 750 °C to less than or equal to 925 °C, such as greater than or equal to 775 °C to less than or equal to 925 °C, greater than or equal to 800 °C to less than or equal to 925 °C, greater than or equal to 825 °C to less than or equal to 925 °C, or greater than or equal to 850 °C to less than or equal to 925 °C, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have a softening point of greater than or equal to 725 °C to less than or equal to 900 °C, greater than or equal to 725 °C to less than or equal to 875 °C, greater than or equal to 725 °C to less than or equal to 850 °C, greater than or equal to 725 °C to less than or equal to 825 °C, or greater than or equal to 725 °C to less than or equal to 800 °C, and all ranges and sub-ranges between the foregoing values. The softening point values stated in this disclosure refer to values measured according to the Fiber Tensile Method of ASTM C338-93(2013).

[0235] The amount of lithium in the glass composition also has an effect on the liquidus viscosity of the glass composition. In embodiments, the liquidus viscosity is less than or equal to 300 kP, for example: less than or equal to 275 kP, less than or equal to 250 kP, less than or equal to 225 kP, less than or equal to 200 kP, less than or equal to 175 kP, or less than or equal to 150 kP. In other embodiments, the liquidus viscosity is greater than or equal to 100 kP, greater than or equal to 125 kP, greater than or equal to 150 kP, greater than or equal to 175 kP, greater than or equal to 200 kP, greater than or equal to 225 kP, greater than or equal to 250 kP, or greater than or equal to 275 kP. In other embodiments, the liquidus viscosity is greater than or equal to 100 kP to less than or equal to 300 kP, greater than or equal to 125 kP to less than or equal to 275 kP, greater than or equal to 150 kP to less than or equal to 250 kP, or greater than or equal to 175 kP to less than or equal to 225 kP, and all ranges and sub-ranges therebetween. The liquidus viscosity values are determined by first measuring the liquidus temperature of the glass according to ASTM C829-81 (2015), entitled “Standard Practice for Measurement of Liquidus Temperature of Glass by the Gradient Furnace Method.” Next, the viscosity of the glass at the liquidus temperature is measured according to ASTM C965-96 (2012), entitled “Standard Practice for Measuring Viscosity of Glass Above the Softening Point.”

[0236] The addition of lithium to the glass composition also affects the Young’s modulus, shear modulus, and Poisson’s ratio of the glass composition. In embodiments, the Young’s modulus of the glass composition can be: greater than or equal to 65 GPa to less than or equal to 85 GPa, such as greater than or equal to 67 GPa to less than or equal to 82 GPa, greater than or equal to 70 GPa to less than or equal to 80 GPa, greater than or equal to 72 GPa to less than or equal to 78 GPa, or greater than or equal to 74 GPa to less than or equal to 76 GPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the Young’s modulus of the glass composition can be: greater than or equal to 66 GPa to less than or equal to 85 GPa, greater than or equal to 68 GPa to less than or equal to 85 GPa, greater than or equal to 70 GPa to less than or equal to 85 GPa, greater than or equal to 72 GPa to less than or equal to 85 GPa, greater than or equal to 74 GPa to less than or equal to 85 GPa, greater than or equal to 76 GPa to less than or equal to 85 GPa, greater than or equal to 78 GPa to less than or equal to 85 GPa, greater than or equal to 80 GPa to less than or equal to 85 GPa, or greater than or equal to 82 GPa to less than or equal to 85 GPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the Young’s modulus of the glass composition can be: greater than or equal to 65 GPa to less than or equal to 84 GPa, greater than or equal to 65 GPa to less than or equal to 82 GPa, greater than or equal to 65 GPa to less than or equal to 80 GPa, greater than or equal to 65 GPa to less than or equal to 78 GPa, greater than or equal to 65 GPa to less than or equal to 76 GPa, greater than or equal to 65 GPa to less than or equal to 74 GPa, greater than or equal to 65 GPa to less than or equal to 72 GPa, greater than or equal to 65 GPa to less than or equal to 70 GPa, greater than or equal to 65 GPa to less than or equal to 68 GPa, or greater than or equal to 65 GPa to less than or equal to 66 GPa, and all ranges and sub-ranges between the foregoing values. The Young’s modulus values stated in the present disclosure refer to values measured by a general type of resonant ultrasonic spectroscopy technique as set forth in ASTM E2001-13, entitled “Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts.”

[0237] According to some embodiments, the glass composition can have a shear modulus of: greater than or equal to 25 GPa to less than or equal to 35 GPa, such as greater than or equal to 26 GPa to less than or equal to 34 GPa, greater than or equal to 27 GPa to less than or equal to 33 GPa, greater than or equal to 28 GPa to less than or equal to 32 GPa, or greater than or equal to 29 GPa to less than or equal to 31 GPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have a shear modulus of: greater than or equal to 26 GPa to less than or equal to 35 GPa, greater than or equal to 27 GPa to less than or equal to 35 GPa, greater than or equal to 28 GPa to less than or equal to 35 GPa, greater than or equal to 29 GPa to less than or equal to 35 GPa, greater than or equal to 30 GPa to less than or equal to 35 GPa, greater than or equal to 31 GPa to less than or equal to 35 GPa, greater than or equal to 32 GPa to less than or equal to 35 GPa, greater than or equal to 33 GPa to less than or equal to 35 GPa, or greater than or equal to 34 GPa to less than or equal to 35 GPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have a shear modulus of: greater than or equal to 25 GPa to less than or equal to 34 GPa, greater than or equal to 25 GPa to less than or equal to 33 GPa, greater than or equal to 25 GPa to less than or equal to 32 GPa, greater than or equal to 25 GPa to less than or equal to 31 GPa, greater than or equal to 25 GPa to less than or equal to 30 GPa, greater than or equal to 25 GPa to less than or equal to 29 GPa, greater than or equal to 25 GPa to less than or equal to 28 GPa, greater than or equal to 25 GPa to less than or equal to 27 GPa, or greater than or equal to 25 GPa to less than or equal to 26 GPa, and all ranges and sub-ranges between the foregoing values. The shear modulus values stated herein refer to values measured by a general type of resonant ultrasonic spectroscopy technique set forth in ASTM E2001-13, entitled“Standard Guide for Resonant Ultrasonic Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts.”

[0238] In one or more embodiments, the glass articles described herein can exhibit an amorphous microstructure, and can be substantially free of crystals or crystallites. In other words, the glass articles exclude glass-ceramic materials.

[0239] In some embodiments, the as-formed glasses disclosed herein have a refractive index ("RI 刚形成 ") at a 589 nm wavelength that is lower than a refractive index ("RI 经退火 ") at a 589 nm wavelength measured when the glass is heated at the anneal point for 1 hour. In some embodiments, RI 经退火 - RI 刚形成 is greater than or equal to 0.0003, greater than or equal to 0.0004, greater than or equal to 0.0005, greater than or equal to 0.0006, greater than or equal to 0.0007, greater than or equal to 0.0008, greater than or equal to 0.0009. In some embodiments, RI 经退火 - RI 刚形成 is: 0.0003 to 0.001, 0.0003 to 0.0009, 0.0003 to 0.0008, 0.0003 to 0.0007, 0.0003 to 0.0006, 0.0003 to 0.0005, 0.0003 to 0.0004, 0.0004 to 0.001, 0.0004 to 0.0009, 0.0004 to 0.0008, 0.0004 to 0.0007, 0.0004 to 0.0006, 0.0004 to 0.0005, 0.0005 to 0.001, 0.0005 to 0.0009, 0.0005 to 0.0008, 0.0005 to 0.0007, 0.0005 to 0.0006, 0.0006 to 0.001, 0.0006 to 0.0009, 0.0006 to 0.0008, 0.0006 to 0.0007, 0.0007 to 0.001, 0.0007 to 0.0009, 0.0007 to 0.0008, 0.0008 to 0.001, 0.0008 to 0.0009, or 0.0009 to 0.001. As used herein, the term "as-formed" refers to the glass after its formation (i.e., after a float process or a down-draw process) and prior to additional heat treatment of the glass.

[0240] As described above, in embodiments, the Li-containing aluminosilicate glass compositions can be strengthened, e.g., by ion exchange, to produce a glass that is damage resistant for applications such as display cover glasses, but not limited thereto. See, e.g., U.S. Patent No. 6, 676, 822, which is incorporated herein by reference in its entirety. Figure 23 The glass has a first region under compressive stress (e.g., the first and second compressive layers 520 and 522 in Figure 23 ) and a second region under tensile stress or central tension (CT) (e.g., the core layer 524 in Figure 23a first region extending from the surface to a depth of compression (DOC) of the glass, and a second region extending from the DOC into a central or interior region of the glass. As used herein, DOC refers to the depth within a glass article where the stress changes from compressive to tensile. At the DOC, the stress transitions from a positive (compressive) stress to a negative (tensile) stress, thus exhibiting a zero stress value.

[0241] According to common practice in the art, compressive or compressive stress is represented as a negative stress (<0) and tensile or tensile stress is represented as a positive stress (>0). However, throughout this specification, CS is represented as a positive value or absolute value, i.e., CS as stated herein = |CS|. Compressive stress (CS) has a maximum value at the surface of the glass, and CS varies as a function of distance d from the surface. See again Figure 23 , a first segment 520 extends from the first surface 510 to a depth dl, and a second segment 522 extends from the second surface 512 to a depth d2. Together, these segments define the compressive or CS of the glass 500. Compressive stress (including surface CS) is measured by surface stress meter (FSM), using a commercial instrument such as the FSM-6000 manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurement relies on the accurate measurement of the stress optical coefficient (SOC), which is related to the birefringence of the glass. In turn, SOC is measured according to Procedure C (Glass Disc Method) described in ASTM Standard C770-16, entitled “Standard Test Method for Measurement of Glass Stress-Optical Coefficient,” which is incorporated herein by reference in its entirety.

[0242] In some embodiments, the CS is greater than or equal to 300 MPa to less than or equal to 950 MPa, for example, greater than or equal to 325 MPa to less than or equal to 950 MPa, greater than or equal to 350 MPa to less than or equal to 950 MPa, greater than or equal to 375 MPa to less than or equal to 950 MPa, greater than or equal to 400 MPa to less than or equal to 950 MPa, greater than or equal to 425 MPa to less than or equal to 950 MPa, greater than or equal to 450 MPa to less than or equal to 950 MPa, greater than or equal to 475 MPa to less than or equal to 950 MPa, greater than or equal to 500 MPa to less than or equal to 950 MPa, greater than or equal to 525 MPa to less than or equal to 950 MPa, greater than or equal to 550 MPa to less than or equal to 950 MPa, greater than or equal to 575 MPa to less than or equal to 950 MPa, greater than or equal to 600 MPa to less than or equal to 950 MPa, greater than or equal to 625 MPa to less than or equal to 950 MPa, greater than or equal to 650 MPa to less than or equal to 950 MPa, or greater than or equal to 675 MPa to less than or equal to 950 MPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the CS is greater than or equal to 300 MPa to less than or equal to 925 MPa, greater than or equal to 300 MPa to less than or equal to 900 MPa, greater than or equal to 300 MPa to less than or equal to 875 MPa, greater than or equal to 300 MPa to less than or equal to 850 MPa, greater than or equal to 300 MPa to less than or equal to 825 MPa, greater than or equal to 300 MPa to less than or equal to 800 MPa, greater than or equal to 300 MPa to less than or equal to 775 MPa, greater than or equal to 300 MPa to less than or equal to 750 MPa, greater than or equal to 300 MPa to less than or equal to 725 MPa, greater than or equal to 300 MPa to less than or equal to 700 MPa, greater than or equal to 300 MPa to less than or equal to 675 MPa, greater than or equal to 300 MPa to less than or equal to 650 MPa, greater than or equal to 300 MPa to less than or equal to 625 MPa, greater than or equal to 300 MPa to less than or equal to 600 MPa, greater than or equal to 300 MPa to less than or equal to 575 MPa, greater than or equal to 300 MPa to less than or equal to 550 MPa, or greater than or equal to 300 MPa to less than or equal to 525 MPa, and all ranges and sub-ranges between the foregoing values.

[0243] In one or more embodiments, Na + and K +ion exchange into the glass article, and Na + the depth of ion diffusion into the glass article is greater for K + than for Na. K + The depth of penetration of the ions (“potassium DOL”) is different than the DOC because it represents the depth of potassium penetration as a result of the ion exchange process. In some embodiments, for the articles described herein, the potassium DOL is generally less than the DOC. Potassium DOL is measured using a surface stress meter (e.g., a commercially available FSM-6000 surface stress meter manufactured by Orihara Industrial Co., Ltd. (Japan)) that relies on precise measurements of the stress optical coefficient (SOC), as described above with respect to CS measurements. In some embodiments, the potassium DOL of the first and second compressive stress layers 520, 522 is, respectively: greater than or equal to 5 pm to less than or equal to 30 pm, such as greater than or equal to 6 pm to less than or equal to 25 pm, greater than or equal to 7 pm to less than or equal to 20 pm, greater than or equal to 8 pm to less than or equal to 15 pm, or greater than or equal to 9 pm to less than or equal to 10 pm, and all ranges and sub-ranges between the foregoing values. In some embodiments, the potassium DOL of the first and second compressive stress layers 520, 522 is, respectively: greater than or equal to 6 pm to less than or equal to 30 pm, greater than or equal to 10 pm to less than or equal to 30 pm, greater than or equal to 15 pm to less than or equal to 30 pm, greater than or equal to 20 pm to less than or equal to 30 pm, or greater than or equal to 25 pm to less than or equal to 30 pm, and all ranges and sub-ranges between the foregoing values. In other embodiments, the potassium DOL of the first and second compressive stress layers 520, 522 is, respectively: greater than or equal to 5 pm to less than or equal to 25 pm, greater than or equal to 5 pm to less than or equal to 20 pm, greater than or equal to 5 pm to less than or equal to 15 pm, or greater than or equal to 5 pm to less than or equal to 10 pm, and all ranges and sub-ranges between the foregoing values.

[0244] two major surfaces (A Figure 23The compressive stress in the center of the glass (510, 512) is balanced by the tensile stress stored in the center region of the glass (530). The maximum center tension (CT) and DOC values are measured using a scattered light polariscope (SCALP) technique known in the art. The stress profile can be measured using a refracted near field (RNF) method or SCALP. When the RNF method is used to measure the stress profile, the maximum CT value provided by SCALP is used in the RNF method. Specifically, the stress profile measured by RNF is force balanced and calibrated with the maximum CT value provided by the SCALP measurement. The RNF method is described in U.S. Patent No. 8,854,623, entitled "Systems and methods for measuring a profile characteristic of a glass sample," which is incorporated herein by reference in its entirety. Specifically, the RNF method includes placing a glass article proximate to a reference block, generating a polarization-switched light beam that switches between orthogonal polarizations at a rate of 1-50 Hz, measuring an amount of power in the polarization-switched light beam, and generating a polarization-switched reference signal, wherein the amount of power measured in each orthogonal polarization is within 50% of each other. The method further includes passing the polarization-switched light beam through the glass sample and the reference block to different depths in the glass sample, and then delaying the passed polarization-switched light beam using a delay optical system to a signal light detector that generates a polarization-switched detector signal. The method further includes dividing the detector signal by the reference signal to form a normalized detector signal, and determining a profile characteristic of the glass sample from the normalized detector signal.

[0245] In embodiments, the glass composition can have a maximum CT of greater than or equal to 30 MPa to less than or equal to 150 MPa, for example, greater than or equal to 35 MPa to less than or equal to 125 MPa, greater than or equal to 40 MPa to less than or equal to 120 MPa, greater than or equal to 45 MPa to less than or equal to 115 MPa, greater than or equal to 50 MPa to less than or equal to 110 MPa, greater than or equal to 55 MPa to less than or equal to 105 MPa, greater than or equal to 60 MPa to less than or equal to 100 MPa, greater than or equal to 65 MPa to less than or equal to 95 MPa, or greater than or equal to 70 MPa to less than or equal to 90 MPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have a maximum CT of greater than or equal to 30 MPa to less than or equal to 150 MPa, greater than or equal to 35 MPa to less than or equal to 150 MPa, greater than or equal to 40 MPa to less than or equal to 150 MPa, greater than or equal to 45 MPa to less than or equal to 150 MPa, greater than or equal to 50 MPa to less than or equal to 150 MPa, greater than or equal to 55 MPa to less than or equal to 150 MPa, greater than or equal to 60 MPa to less than or equal to 150 MPa, greater than or equal to 65 MPa to less than or equal to 150 MPa, greater than or equal to 70 MPa to less than or equal to 150 MPa, greater than or equal to 75 MPa to less than or equal to 150 MPa, greater than or equal to 80 MPa to less than or equal to 150 MPa, greater than or equal to 85 MPa to less than or equal to 150 MPa, greater than or equal to 90 MPa to less than or equal to 150 MPa, greater than or equal to 95 MPa to less than or equal to 150 MPa, greater than or equal to 100 MPa to less than or equal to 150 MPa, greater than or equal to 105 MPa to less than or equal to 150 MPa, greater than or equal to 110 MPa to less than or equal to 150 MPa, greater than or equal to 115 MPa to less than or equal to 150 MPa, greater than or equal to 120 MPa to less than or equal to 150 MPa, or greater than or equal to 125 MPa to less than or equal to 150 MPa, and all ranges and sub-ranges between the foregoing values.In some embodiments, the glass composition can have a maximum CT of: greater than or equal to 30 MPa to less than or equal to 125 MPa, greater than or equal to 30 MPa to less than or equal to 120 MPa, greater than or equal to 30 MPa to less than or equal to 115 MPa, greater than or equal to 30 MPa to less than or equal to 110 MPa, greater than or equal to 30 MPa to less than or equal to 105 MPa, greater than or equal to 30 MPa to less than or equal to 100 MPa, greater than or equal to 30 MPa to less than or equal to 95 MPa, greater than or equal to 30 MPa to less than or equal to 90 MPa, greater than or equal to 30 MPa to less than or equal to 85 MPa, greater than or equal to 30 MPa to less than or equal to 80 MPa, greater than or equal to 30 MPa to less than or equal to 75 MPa, greater than or equal to 30 MPa to less than or equal to 70 MPa, greater than or equal to 30 MPa to less than or equal to 65 MPa, greater than or equal to 30 MPa to less than or equal to 60 MPa, greater than or equal to 30 MPa to less than or equal to 55 MPa, greater than or equal to 30 MPa to less than or equal to 50 MPa, greater than or equal to 30 MPa to less than or equal to 45 MPa, greater than or equal to 30 MPa to less than or equal to 40 MPa, or greater than or equal to 30 MPa to less than or equal to 35 MPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have a maximum CT of: greater than or equal to 30 MPa to less than or equal to 100 MPa, and all ranges and sub-ranges between the foregoing values. In other embodiments, the glass composition can have a maximum CT of: greater than or equal to 70 MPa to less than or equal to 150 MPa, or greater than or equal to 75 MPa to less than or equal to 150 MPa, and all ranges and sub-ranges between the foregoing values.

[0246] As described above, the DOC is measured using a scattered light polariscope (SCALP) technique known in the art. The DOC provided herein is as a fraction of the thickness (t) of the glass article. In embodiments, the depth of compression (DOC) of the glass composition can be: greater than or equal to 0.15t to less than or equal to 0.25t, such as greater than or equal to 0.17t to less than or equal to 0.23t or greater than or equal to 0.19t to less than or equal to 0.21t, and all ranges and sub-ranges between the foregoing values. In other embodiments, the DOC of the glass composition can be: greater than or equal to 0.16t to less than or equal to 0.2t, greater than or equal to 0.17t to less than or equal to 0.25t, greater than or equal to 0.18t to less than or equal to 0.25t, greater than or equal to 0.19t to less than or equal to 0.25t, greater than or equal to 0.20t to less than or equal to 0.25t, greater than or equal to 0.21t to less than or equal to 0.25t, greater than or equal to 0.22t to less than or equal to 0.25t, greater than or equal to 0.23t to less than or equal to 0.25t, or greater than or equal to 0.24t to less than or equal to 0.25t, and all ranges and sub-ranges between the foregoing values. In other embodiments, the DOC of the glass composition can be: greater than or equal to 0.15t to less than or equal to 0.24t, greater than or equal to 0.15t to less than or equal to 0.23t, greater than or equal to 0.15t to less than or equal to 0.22t, greater than or equal to 0.15t to less than or equal to 0.21t, greater than or equal to 0.15t to less than or equal to 0.20t, greater than or equal to 0.15t to less than or equal to 0.19t, greater than or equal to 0.15t to less than or equal to 0.18t, greater than or equal to 0.15t to less than or equal to 0.17t, or greater than or equal to 0.15t to less than or equal to 0.16t, and all ranges and sub-ranges between the foregoing values.

[0247] A compressive stress layer can be formed in the glass by exposing the glass to an ion exchange solution. In embodiments, the ion exchange solution can be a molten nitrate salt. In some embodiments, the ion exchange solution can be molten KNO3, molten NaNO3, or a combination thereof. In certain embodiments, the ion exchange solution can comprise about 100% molten KNO3, about 90% molten KNO3, about 80% molten KNO3, about 70% molten KNO3, or about 60% molten KNO3. In certain embodiments, the ion exchange solution can comprise about 10% molten NaNO3, about 20% molten NaNO3, about 30% molten NaNO3, or about 40% molten NaNO3. In other embodiments, the ion exchange solution can comprise about 80% molten KNO3and about 20% molten NaNO3, about 75% molten KNO3and about 25% molten NaNO3, about 70% molten KNO3and about 30% molten NaNO3, about 65% molten KNO3and about 35% molten NaNO3, or about 60% molten KNO3and about 40% molten NaNO3, and all ranges and sub-ranges between the foregoing values. In embodiments, other sodium and potassium salts can be used in the ion exchange solution, for example, sodium or potassium nitrite, sodium or potassium phosphate, or sodium or potassium sulfate.

[0248] The glass composition can be exposed to the ion exchange solution by immersing a glass article made from the glass composition in an ion exchange solution bath, spraying the ion exchange solution onto a glass article made from the glass composition, or any other manner of physically applying the ion exchange solution to a glass article made from the glass composition. According to embodiments, the temperature of the ion exchange solution can be greater than or equal to 400 °C to less than or equal to 500 °C, for example, greater than or equal to 410 °C to less than or equal to 490 °C, greater than or equal to 420 °C to less than or equal to 480 °C, greater than or equal to 430 °C to less than or equal to 470 °C, or greater than or equal to 440 °C to less than or equal to 460 °C, and all ranges and sub-ranges between the foregoing values, after exposure to the glass composition. In embodiments, the glass composition can be exposed to the ion exchange solution for a time greater than or equal to 4 hours to less than or equal to 48 hours, for example, greater than or equal to 8 hours to less than or equal to 44 hours, greater than or equal to 12 hours to less than or equal to 40 hours, greater than or equal to 16 hours to less than or equal to 36 hours, greater than or equal to 20 hours to less than or equal to 32 hours, or greater than or equal to 24 hours to less than or equal to 28 hours, and all ranges and sub-ranges between the foregoing values.

[0249] Ion exchange processes can be performed in ion exchange solutions under processing conditions that provide the improved compressive stress profiles disclosed, such as U.S. Patent Application Publication No. 2016 / 0102011, which is incorporated herein by reference in its entirety.

[0250] The glass articles disclosed herein have improved scratch resistance compared to other glasses. As used herein, the Knoop scratch lateral crack threshold is the onset of lateral cracking (3 or more lateral cracks out of 5 indentation events). In the Knoop scratch lateral crack threshold test, a sample and article of the glass article are first indented with a Knoop indenter with a dynamic or increasing load to identify the lateral crack onset load range for the sample population. Once the load range that can be applied is identified, a series of increasing constant load indentations (minimum of 3 or greater per load) are performed to identify the Knoop scratch threshold. The Knoop scratch threshold range can be determined by comparing the test specimen to one of the following 3 failure modes: 1) a persistent lateral surface crack that is more than twice the width of the indentation; 2) a break confined to the indentation but with a lateral surface crack less than twice the width of the indentation and with breakage visible to the unaided eye; or 3) a large subsurface lateral crack that is greater than 2 times the width of the indentation and / or with a moderate crack at the indentation apex.

[0251] In an embodiment, the threshold for transverse cracking of Knoop scratches on glass articles can be: greater than or equal to 5 N to less than or equal to 24 N, for example, greater than or equal to 6 N to less than or equal to 22 N, greater than or equal to 8 N to less than or equal to 20 N, greater than or equal to 10 N to less than or equal to 18 N, or greater than or equal to 12 N to less than or equal to 16 N, as well as all ranges and subranges between the above values. In other embodiments, the Knoop scratch transverse cracking threshold of the glass article can be: greater than or equal to 6 N and less than or equal to 24 N, greater than or equal to 7 N and less than or equal to 24 N, greater than or equal to 8 N and less than or equal to 24 N, greater than or equal to 9 N and less than or equal to 24 N, greater than or equal to 10 N and less than or equal to 24 N, greater than or equal to 11 N and less than or equal to 24 N, greater than or equal to 12 N and less than or equal to 24 N, greater than or equal to 13 N and less than or equal to 24 N, greater than or equal to 14 N and less than or equal to 24 N, greater than or equal to 15 N and less than or equal to 24 N, greater than or equal to 16 N and less than or equal to 24 N, greater than or equal to 17 N and less than or equal to 24 N, greater than or equal to 18 N and less than or equal to 24 N, greater than or equal to 19 N and less than or equal to 24 N, greater than or equal to 20 N and less than or equal to 24 N, greater than or equal to 21 N and less than or equal to 24 N, greater than or equal to 2 ... N is greater than or equal to 23 N to less than or equal to 24 N to less than or equal to 24 N, and all ranges and subranges between the above values. In other embodiments, the Knoop scratch transverse cracking threshold of the glass article can be: greater than or equal to 5 N and less than or equal to 23 N, greater than or equal to 5 N and less than or equal to 22 N, greater than or equal to 5 N and less than or equal to 21 N, greater than or equal to 5 N and less than or equal to 20 N, greater than or equal to 5 N and less than or equal to 19 N, greater than or equal to 5 N and less than or equal to 18 N, greater than or equal to 5 N and less than or equal to 17 N, greater than or equal to 5 N and less than or equal to 16 N, greater than or equal to 5 N and less than or equal to 15 N, greater than or equal to 5 N and less than or equal to 14 N, greater than or equal to 5 N and less than or equal to 13 N, greater than or equal to 5 N and less than or equal to 12 N, greater than or equal to 5 N and less than or equal to 11 N, greater than or equal to 5 N and less than or equal to 10 N, greater than or equal to 5 N and less than or equal to 9 N, greater than or equal to 5 N and less than or equal to 8 N, greater than or equal to 5 N and less than or equal to 7 N, or greater than or equal to 5 N and less than or equal to 6 N. N, and all ranges and subranges between the above values.

[0252] The glass articles disclosed herein have improved indentation resistance compared to other glasses. The indentation fracture threshold (or Vickers crack initiation threshold) is measured by a Vickers Indenter. The indentation fracture threshold is a measure of the indentation resistance of the glass. The test involves the use of a square pyramid shaped diamond indenter with a face angle of 136°, referred to as a Vickers indenter. The Vickers indenter is the same as that used for standard microhardness testing (see ASTM-E384-11). A minimum of 5 specimens are selected to be representative of the glass type and / or class of interest. For each specimen, a set of 5 indents is introduced into the specimen surface, with the 5 indents in each set being introduced at a given load, with each individual indent spaced a minimum of 5 mm apart and no less than 5 mm from the edge of the specimen. For cases where the test load is > 2 kg, a 50 kg / min indenter load / unload rate is used. For cases where the test load is < 2 kg, a 5 kg / min rate is used. A 10 second dwell time (i.e., hold time) is employed at the target load. During the dwell time, the machine maintains load control. After a period of at least 12 hours, the indents are examined under reflected light using a compound microscope at 500X magnification. Then, for each indent, the presence or absence of a median / radial crack or specimen fracture is recorded. Note that since the formation of median / radial cracks or specimen fracture is of interest for this test, the formation of lateral cracks is not considered to be an indication of threshold behavior. The specimen threshold is defined as the midpoint of the lowest consecutive indent load where greater than 50% of the individual indents fall above the threshold. For example, if 2 individual specimens (40%) out of 5 specimens have indents introduced at a 5 kg load that exceed the threshold, and 3 individual specimens (60%) out of 5 specimens have indents introduced at a 6 kg load that exceed the threshold, then the specimen threshold would be defined as the midpoint of 5 and 6 kg, or 5.5 kg. The sample average threshold is defined as the arithmetic average of all individual specimen thresholds. As with the average, the range of all specimen midpoints (lowest to highest) is also recorded for each sample. The pre-test, test, and post-test environments are controlled at 23 ± 2 °C and 50 ± 5% RH to minimize variations in the fatigue (stress corrosion) behavior of the glass specimens. It should be noted that when testing a composition or variety for the first time, the required indenter load and bracketing increment are typically determined by conducting an "iterative study". Once the performance of the sample is familiarized, subsequent testing can be conducted in a streamlined fashion, testing only those thresholds near the expected threshold, then "filling in" additional indenter loads only as needed.

[0253] In embodiments, the indentation fracture threshold is: greater than or equal to 15 kgf, for example greater than or equal to 15.5 kgf, greater than or equal to 16 kgf, greater than or equal to 16.5 kgf, greater than or equal to 17 kgf, greater than or equal to 17.5 kgf, greater than or equal to 18 kgf, greater than or equal to 18.5 kgf, greater than or equal to 19 kgf, greater than or equal to 19.5 kgf, greater than or equal to 20 kgf, greater than or equal to 15.5 kgf, greater than or equal to 20.5 kgf, greater than or equal to 21 kgf, greater than or equal to 21.5 kgf, greater than or equal to 22 kgf, greater than or equal to 22.5 kgf, and all ranges and sub-ranges therebetween. In some embodiments, the indentation fracture threshold is: less than or equal to 28 kgf, less than or equal to 27.5 kgf, less than or equal to 27 kgf, less than or equal to 26.5 kgf, less than or equal to 26 kgf, or less than or equal to 25.5 kgf, and all ranges and sub-ranges therebetween. In other embodiments, the indentation fracture threshold is: greater than or equal to 15 kgf to less than or equal to 28 kgf, greater than or equal to 16 kgf to less than or equal to 28 kgf, greater than or equal to 17 kgf to less than or equal to 28 kgf, greater than or equal to 18 kgf to less than or equal to 28 kgf, greater than or equal to 19 kgf to less than or equal to 28 kgf, greater than or equal to 20 kgf to less than or equal to 28 kgf, greater than or equal to 21 kgf to less than or equal to 28 kgf, greater than or equal to 22 kgf to less than or equal to 28 kgf, greater than or equal to 23 kgf to less than or equal to 28 kgf, greater than or equal to 24 kgf to less than or equal to 28 kgf, greater than or equal to 25 kgf to less than or equal to 28 kgf, greater than or equal to 26 kgf to less than or equal to 28 kgf, or greater than or equal to 27 kgf to less than or equal to 28 kgf, and all ranges and sub-ranges therebetween.In other embodiments, the indentation fracture threshold is: greater than or equal to 15 kgf to less than or equal to 27 kgf, greater than or equal to 15 kgf to less than or equal to 26 kgf, greater than or equal to 15 kgf to less than or equal to 25 kgf, greater than or equal to 15 kgf to less than or equal to 24 kgf, greater than or equal to 15 kgf to less than or equal to 23 kgf, greater than or equal to 15 kgf to less than or equal to 22 kgf, greater than or equal to 15 kgf to less than or equal to 21 kgf, greater than or equal to 15 kgf to less than or equal to 20 kgf, greater than or equal to 15 kgf to less than or equal to 19 kgf, greater than or equal to 15 kgf to less than or equal to 18 kgf, greater than or equal to 17 kgf to less than or equal to 26 kgf, or greater than or equal to 15 kgf to less than or equal to 16 kgf, and all ranges and sub-ranges between the foregoing values.

[0254] The glass articles disclosed herein can be incorporated into another article, such as an article having a display screen (or display article) (e.g., a consumer electronic, including a mobile phone, a tablet, a computer, and a navigation system, etc.), a building article, a transportation article (e.g., a vehicle, a train, an aircraft, a marine vessel, etc.), an appliance article, or any article that requires partial transparency, scratch resistance, wear resistance, or a combination thereof. Exemplary articles incorporating any of the glass articles disclosed herein are shown in FIGS. Figure 26A and 26B Specifically, Figure 26A and 26B A consumer electronic 500 is shown, which includes a housing 502 having a front surface 504, a back surface 506, and side surfaces 508; (not shown) electronic components at least partially or entirely within the housing and including at least a controller, a memory, and a display 510 located on or adjacent to the front surface of the housing; and a cover substrate 512 located on or over the front surface of the housing such that it is located over the display. In some embodiments, at least one of the housing 502 or a portion of the cover substrate 512 can include any of the glass articles disclosed herein.

[0255] As noted above, the glass compositions according to embodiments can be formed by any suitable method, such as: slot forming, float forming, a roll process, a fusion forming process, etc.

[0256] Exemplary glass articles can be characterized by the manner in which they are formed. For example, a glass article can be characterized as being float formable (i.e., formed by a float process), down-drawable, in particular, fusion formable, or slot drawable (i.e., formed by a down-draw process such as a fusion draw process or a slot draw process).

[0257] Some embodiments of the glass articles described herein can be formed by a down-draw process. Down-draw processes produce glass articles having a uniform thickness with a pristine surface. Because the average flexural strength of the glass article is controlled by the amount and size of surface flaws, the pristine surface, which has had minimal contact, has a higher initial strength. In addition, down-drawn glass articles have very flat, smooth surfaces that can be used in final applications without costly grinding and polishing.

[0258] Some embodiments of the glass articles can be described as fusion formable (i.e., can be formed using a fusion draw process). The fusion process uses a draw tank having a channel to accept a molten glass feedstock. The channel has a weir that is open along the length of the channel at the top on both sides of the channel. When the channel is filled with molten material, the molten glass overflows the weir. Under the influence of gravity, the molten glass flows down the outer surfaces of the draw tank as two flowing glass films. The outer surfaces of the draw tank extend downward and inward such that they join at an edge below the draw tank. The two flowing glass films join at this edge to fuse and form a single flowing glass article. When the two flowing glass films fuse together, a fusion line is formed. The presence of a fusion line is one way to identify a fusion drawn glass article. When the glass is viewed under an optical microscope, the fusion line can be seen as an optical distortion. The advantage of the fusion draw method is that because the two glass films that overflow the channel fuse together, neither outer surface of the resulting glass article has been in contact with any part of the equipment. Thus, the surface properties of the fusion drawn glass article are not affected by such contact.

[0259] Some embodiments of the glass articles described herein can be formed by a slot draw process. The slot draw process is different from the fusion draw method. In the slot draw process, a molten feedstock glass is provided to a draw tank. The bottom of the draw vessel has an open slot with a nozzle extending along the length of the slot. The molten glass flows through the slot / nozzle to be drawn down as a continuous glass article and into an annealing zone.

[0260] Item 1 includes a glass article, comprising, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 74 Si02, greater than or equal to 7 to less than or equal to 18 AI2O3, greater than or equal to 3 to less than or equal to 16 B203, greater than 0 to less than or equal to 6 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, less than or equal to 0.2 Sn02, and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide, wherein the molar ratio AI2O3:(R20 + RO) is greater than or equal to 0.9, where R20 is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent.

[0261] Item 2 includes a glass article, comprising, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 66 Si02, greater than or equal to 11.5 to less than or equal to 18 AI2O3, greater than or equal to 3 to less than or equal to 8 B203, greater than or equal to 2 to less than or equal to 6 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide, wherein the molar ratio AI2O3:(R20 + RO) is greater than or equal to 0.9, where R20 is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent.

[0262] Item 3 includes a glass article, comprising, in mole percent on an oxide basis: greater than or equal to 65 to less than or equal to 74 Si02, greater than or equal to 7 to less than or equal to 12 AI2O3, greater than or equal to 5 to less than or equal to 16 B203, greater than or equal to 0 to less than or equal to 4 Na20, greater than or equal to 0 to less than or equal to 5 P205, greater than or equal to 5 to less than or equal to 11 Li20, and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide, wherein the molar ratio AI2O3:(R20 + RO) is greater than or equal to 0.9, where R20 is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent.

[0263] Item 4 includes the glass article of any of items 2-3, wherein the glass article comprises less than or equal to 0.2 mol% Sn02.

[0264] Item 5 includes the glass article of any of the preceding items, wherein the glass article has a liquidus viscosity of less than or equal to 300 kP.

[0265] Item 6 includes the glass article of any of the preceding items, wherein the glass article comprises a molar ratio of Li20:R20 of greater than or equal to 0.4, where R20 is the sum of alkali metal oxides (in mol%).

[0266] Item 7 includes the glass article of any of the preceding items, wherein the glass article comprises greater than or equal to 80 mol% Al203+ Si02+ B203+ P205.

[0267] Item 8 includes the glass article of any of the preceding items, wherein the glass article comprises greater than or equal to 0.5 mol% to less than or equal to 2 mol% SrO.

[0268] Item 9 includes the glass article of any of the preceding items, wherein the glass article is formed by a fusion process.

[0269] Item 10 includes the glass article of any of the preceding items, wherein the glass article is strengthened by an ion exchange process to form a compressive stress layer on at least one surface of the glass article.

[0270] Item 11 includes the glass article of item 10, wherein the depth of compression (DOC) is greater than or equal to 0.15t, where t is the thickness of the glass article.

[0271] Item 12 includes the glass article of item 10 or 11, wherein the depth of compression (DOC) is greater than or equal to 0.15t to less than or equal to 0.25t, where t is the thickness of the glass article.

[0272] Item 13 includes the glass article of any of items 10-12, wherein the central tension of the glass article is greater than or equal to 30 MPa to less than or equal to 150 MPa.

[0273] Item 14 includes the glass article of item 13, wherein the central tension of the glass article is greater than or equal to 70 MPa to less than or equal to 150 MPa.

[0274] Item 15 includes the glass article of item 13, wherein the central tension of the glass article is greater than or equal to 30 MPa to less than or equal to 100 MPa.

[0275] Item 16 includes the glass article of any of Items 10-15, the glass article being strengthened by an ion exchange process that adds potassium ions to the glass article, and a potassium depth of layer (DOL) is greater than or equal to 5 µm to less than or equal to 30 µm.

[0276] Item 17 includes the glass article of any of Items 10-16, wherein the compressive stress layer has a compressive stress at its surface that is greater than or equal to 300 MPa to less than or equal to 950 MPa.

[0277] Item 18 includes the glass article of any of the preceding items, wherein the glass article has a Knoop Scribe Transverse Crack Threshold that is greater than or equal to 5 N to less than or equal to 24 N.

[0278] Item 19 includes the glass article of any of the preceding items, wherein the glass article has an Indentation Fracture Threshold that is greater than or equal to 15 kgf.

[0279] Item 20 includes the glass article of any of the preceding items, wherein the glass article comprises greater than or equal to 0 mol% to less than or equal to 6.5 mol% MgO.

[0280] Item 21 includes the glass article of any of the preceding items, wherein the glass article comprises greater than or equal to 0 mol% to less than or equal to 5 mol% CaO.

[0281] Item 22 includes the glass article of any of the preceding items, wherein the glass article comprises greater than or equal to 0 mol% to less than or equal to 2 mol% ZnO.

[0282] Item 23 includes a glass article comprising Li2O, SiO2, Al2O3, and a liquidus viscosity that is less than or equal to 300 kP, wherein RI 经退火 - RI 刚形成 is greater than or equal to 0.0003, where RI 经退火 is the refractive index of the glass heated for 1 hour at the anneal point of the glass at a wavelength of 589 nm, and RI 刚形成 is the refractive index of the as-formed glass at a wavelength of 589 nm.

[0283] Item 24 includes the glass article of Item 23, further comprising a fusion line.

[0284] Item 25 includes the glass article of Item 23 or 24, wherein RI 经退火 - RI 刚形成 is 0.0003 to 0.001.

[0285] Item 26 includes the glass article of Item 23 or 24, wherein RI 经退火 - RI 刚形成is 0.0005 to 0.001.

[0286] Item 27 includes the glass article of Item 23 or 24, wherein the R1is greater than or equal to 0.0005. 经退火 - R1 刚形成 is greater than or equal to 0.0005.

[0287] Item 28 includes the glass article of any of Items 23-27, comprising at least one alkali metal oxide (R2O) or divalent cation oxide (RO), wherein the molar ratio Al2O3:(R2O + RO) is greater than or equal to 0.9.

[0288] Item 29 includes the glass article of any of Items 23-28, wherein the glass article comprises a molar ratio Li2O:R2O that is greater than or equal to 0.4, where R2O is the sum of alkali metal oxides (in mol%).

[0289] Item 30 includes the glass article of any of Items 23-29, wherein the glass article comprises greater than or equal to 80 mol% Al2O3 + SiO2 + B2O3 + P2O5.

[0290] Item 31 includes a consumer electronic product comprising: a housing having a front surface, a back surface, and side surfaces; an electronic assembly provided at least partially within the housing, the electronic assembly comprising at least a controller, a memory, and a display, the display being provided at the front surface of the housing or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein at least one of the housing or a portion of the cover substrate comprises the glass article of any of the preceding items.

[0291] Examples

[0292] The embodiments are further illustrated by the following examples. It is to be understood that these examples do not limit the embodiments described above.

[0293] Glass compositions having the components listed in Table 2 below were prepared. In Table 2, all components are in mol%.

[0294] Table 2

[0295]

[0296]

[0297]

[0298]

[0299]

[0300]

[0301] Density, strain point, annealing point, softening point, stress optical coefficient, Young's modulus, and shear modulus were measured according to the techniques described above. Linear coefficient of thermal expansion (CTE) over the temperature range 0-300 C was determined using a push-rod dilatometer according to ASTM E228-11. Poisson's ratio was measured by a general type of resonant ultrasonic spectroscopy technique as set forth in ASTM E2001-13, entitled "Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts."

[0302] Table 3 below shows properties of the various glass compositions provided in Table 2 above. Table 3 also provides the ion exchange solution composition, temperature, and duration of the ion exchange process. CTE, DOC, CS, and Potassium DOL as reported in Table 3 were determined using the measurement techniques described above.

[0303] Table 3

[0304]

[0305] In addition to the data described above, the Knoop scratch lateral crack threshold was tested for glass 49 disclosed in Table 2 above. The results of the Knoop scratch lateral crack threshold test are shown in Figure 24 As shown in this figure, the Knoop scratch lateral crack threshold of glass 49 was higher than the comparative lithium-containing glasses. Glass 49 according to glass 49 was ion exchanged in a 20 wt% NaNCb and 80 wt% KNO3 molten salt bath at 430°C for 10 hours. Comparative glass 1 was ion exchanged in a 20 wt% NaNCb and 80 wt% KNO3 molten salt bath at 430°C for 16 hours. Comparative glass 2 was ion exchanged in a 49 wt% NaNCb and 51 wt% KNO3 molten salt bath at 380°C for 3.75 hours. Each glass was formed into a 0.8 mm thick glass sheet. Table 4 below provides the composition of comparative glass 1 and comparative glass 2 in mole%.

[0306] Table 4

[0307]

[0308] In addition to the data described above, the indentation crack threshold was also tested for glass 49 disclosed in Table 2 above. The results of the indentation crack threshold test are shown in Figure 25The indentation fracture threshold of glass 49 was higher than the comparative lithium-containing glasses, as shown in the figure. Glass articles of glass 49 were ion exchanged in a 20 wt% NaNO3and 80 wt% KNO3molten salt bath at 430°C for 10 hours. Comparative glass 1 was ion exchanged in a 20 wt% NaNO3and 80 wt% KNO3molten salt bath at 430°C for 16 hours. Comparative glass 2 was ion exchanged in a 49 wt% NaNO3and 51 wt% KNO3molten salt bath at 380°C for 3.75 hours. Each glass was formed into a 0.8 mm thick glass sheet.

[0309] It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein and fall within the scope of the appended claims and their equivalents.

Claims

1. A glass article comprising, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 74 Si02; greater than or equal to 7 to less than or equal to 18 AI2O3; greater than or equal to 3 to less than or equal to 10 B203; greater than or equal to 2 to less than or equal to 6 Na20; greater than or equal to 0 to less than or equal to 5 P205; less than or equal to 1 ZnO; greater than or equal to 0.5 to less than or equal to 2 SrO; greater than or equal to 5 to less than or equal to 11 Li20; and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide, wherein: the molar ratio AI2O3:(R2O + RO) is greater than or equal to 0.9, where R2O is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent, and the molar ratio Li20:R2O is greater than or equal to 0.4 to less than or equal to 0.7, where R2O is the sum of alkali metal oxides in mole percent.

2. The glass article of claim 1, wherein, the glass article comprises greater than or equal to 5.5 to less than or equal to 9 Li20 in mole percent.

3. A glass article comprising, in mole percent on an oxide basis: greater than or equal to 60 to less than or equal to 66 Si02; greater than or equal to 11.5 to less than or equal to 18 AI2O3; greater than or equal to 3 to less than or equal to 8 B203; greater than or equal to 2 to less than or equal to 6 Na20; greater than 0 to less than or equal to 5 P205; greater than or equal to 6.5 to less than or equal to 7.5 Li20; and greater than or equal to 0.5 to less than or equal to 6.5 divalent cation oxide, wherein, the molar ratio AI2O3:(R2O + RO) is greater than or equal to 0.9, where R2O is the sum of alkali metal oxides in mole percent and RO is the sum of divalent cation oxides in mole percent, and where the molar ratio Li20:R2O is greater than or equal to 0.4 to less than or equal to 0.7, where R2O is the sum of alkali metal oxides in mole percent.

4. A glass article comprising: greater than or equal to 5 to less than or equal to 11 Li20; greater than or equal to 60 to less than or equal to 74 Si02; greater than or equal to 7 to less than or equal to 18 AI2O3; and less than or equal to 300 kP liquidus viscosity, wherein RI 经退火 -RI 刚形成 is greater than or equal to 0.0003, where RI 经退火 is the refractive index of the glass at a wavelength of 589 nm after heating the glass at the annealing point for 1 hour, and RI 刚形成 is the refractive index of the as-formed glass at a wavelength of 589 nm, and the annealing point of the glass is greater than or equal to 580 °C and less than or equal to 675 °C.

5. The glass article of claim 3, further comprising a fusion line.

6. The glass article of claim 3, wherein, RI 经退火 -RI 刚形成 is 0.0003 to 0.

001.

7. The glass article of claim 3, wherein, RI 经退火 -RI 刚形成 is 0.0005 to 0.

001.

8. The glass article of claim 3, wherein, RI 经退火 -RI 刚形成 is greater than or equal to 0.0005.

9. The glass article of any of claims 1-8, wherein, the glass article comprises less than or equal to 0.2 Sn02in mole percent.

10. The glass article of any of claims 1-8, wherein, the glass article has a liquidus viscosity of less than or equal to 300 kP.

11. The glass article of any of claims 1-8, wherein, the glass article comprises a molar ratio Li20:R2O greater than or equal to 0.5 to less than or equal to 0.7, where R2O is the sum of alkali metal oxides in mole percent.

12. The glass article of any of claims 1-8, wherein, The glass article comprises greater than or equal to 80 mol% Al2O3 + SiO2 + B2O3 + P2O5.

13. The glass article of any of claims 1-8, wherein, The glass article is formed by a fusion process.

14. The glass article of any of claims 1-8, wherein, The glass article is strengthened by an ion exchange process to form a compressive stress layer on at least one surface of the glass article.

15. The glass article of claim 14, wherein, The compressive depth is greater than or equal to 0.15t, where t is the thickness of the glass article.

16. The glass article of claim 14, wherein, The compressive depth (DOC) is greater than or equal to 0.15t to less than or equal to 0.25t, where t is the thickness of the glass article.

17. The glass article of claim 15 or 16, wherein, The central tension of the glass article is greater than or equal to 30 MPa to less than or equal to 150 MPa.

18. The glass article of claim 15 or 16, wherein, The central tension of the glass article is greater than or equal to 70 MPa to less than or equal to 150 MPa.

19. The glass article of claim 15 or 16, wherein, The central tension of the glass article is greater than or equal to 30 MPa to less than or equal to 100 MPa.

20. The glass article of claim 15 or 16, wherein, The glass article is strengthened by an ion exchange process which adds potassium ions to the glass article and the potassium depth of layer (DOL) is greater than or equal to 5 µm to less than or equal to 30 µm.

21. The glass article of claim 15 or 16, wherein, The compressive stress layer has a compressive stress at its surface of greater than or equal to 300 MPa to less than or equal to 950 MPa.

22. The glass article of any of claims 1-8, wherein, The glass article has a Knoop scratch lateral crack threshold of greater than or equal to 5 N to less than or equal to 24 N.

23. The glass article of any of claims 1-8, wherein, The glass article has an indentation fracture threshold of greater than or equal to 15 kgf.

24. The glass article of any of claims 1-8, wherein, The glass article comprises greater than or equal to 0 mol% to less than or equal to 6.5 mol% MgO.

25. The glass article of any of claims 1-8, wherein, The glass article comprises greater than or equal to 0 mol% to less than or equal to 5 mol% CaO.

26. The glass article of any of claims 1-8, wherein, The glass article comprises greater than 0 mol% to less than or equal to 4 mol% CaO.

27. The glass article of any of claims 1-8, wherein, The glass article comprises greater than or equal to 0 mol% to less than or equal to 2 mol% ZnO.

28. The glass article of any of claims 1-8, wherein, The glass article comprises greater than or equal to 11.5 mol% to less than or equal to 18 mol% Al2O3.

29. The glass article of any of claims 1-8, wherein, The glass article comprises greater than or equal to 60 mol% to less than or equal to 66 mol% SiO2.

30. The glass article of any of claims 1-8, wherein, The glass article comprises greater than or equal to 3 mol% to less than or equal to 5 mol% B2O3.

31. The glass article of any one of claims 1-8, wherein, The glass article comprises greater than 0 mol% to less than or equal to 3 mol% P2O5.

32. The glass article of any of claims 1-8, wherein, The glass article comprises greater than 3 mol% to less than or equal to 6 mol% Na2O.

33. A consumer electronic product comprising: a housing having a front surface, a back surface, and side surfaces; electronic components at least including a controller, a memory, and a display provided at least partially within the housing, the display being provided at or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein at least one of a portion of the housing or the cover substrate comprises the glass article of any of claims 1-8.

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