Glass composition having a high Poisson ratio

Abstract

The glass composition comprises 50 mol% or more and 65 mol% SiO2; 2 mol% or more and 25 mol% Al2O3; 1 mol% or more and 40 mol% MgO; 3 mol% or more and 17 mol% Li2O; and 1 mol% or more and 10 mol% Na2O. The glass composition is substantially free of La2O3 and Y2O3. The glass composition has a Poisson ratio of 0.24 or higher. The glass composition is ion-exchangeable.

Description

Technology Field

[0001] This application claims the benefit of U.S. provisional application serial number 63 / 119062 filed on November 30, 2020, the contents of which are relied upon and incorporated herein by reference. Background Technology

[0002] This specification generally relates to a glass composition suitable for use as a cover glass for electronic devices. More specifically, this specification relates to an ion-exchangeable glass that can be formed into a cover glass for electronic devices.

[0003] The mobility of portable devices such as smartphones, tablets, portable media players, personal computers, and cameras makes them particularly vulnerable to accidental drops on hard surfaces like floors. These devices typically incorporate cover glass that can be damaged upon impact with a hard surface. In many of these devices, the cover glass serves as a display cover and incorporates touch functionality, so damage to the cover glass can negatively impact the device's usability.

[0004] When a connected portable device falls onto a hard surface, there are two main failure modes of the cover glass. One of these modes is bending failure, which occurs due to the bending of the glass when the device is subjected to dynamic loads from impact with the hard surface. The other mode is sharp contact failure, which occurs due to the introduction of damage to the glass surface. Collision between the glass and rough, hard surfaces, such as asphalt or granite, can result in indentations on the glass surface. These indentations become the sites of failure where cracks can develop and propagate on the glass surface.

[0005] Glass can enhance its resistance to bending fracture through ion exchange technology that involves inducing compressive stress on the glass surface. However, ion-exchanged glass will still be vulnerable to dynamic sharp contact due to high stress concentrations caused by localized marks on the glass resulting from sharp contact.

[0006] Glass manufacturers and handheld device manufacturers have continuously strived to improve the resistance of handheld devices to sharp contact breakage. Various solutions exist, ranging from cover glass coatings to bezels that prevent the cover glass from directly impacting a hard surface when the device is dropped. However, due to constraints in aesthetic and functional requirements, it is very difficult to completely prevent the cover glass from impacting a hard surface.

[0007] Furthermore, it is desirable to make portable devices as thin as possible. Therefore, the glass used as the cover glass for portable devices should be as thin as possible, in addition to having high strength. Thus, in addition to increasing the strength of the cover glass, it is desirable for the glass to possess mechanical properties that allow it to be formed by a process capable of creating thin glass articles, such as thin glass sheets.

[0008] Therefore, there is a need for glass having mechanical properties that can be strengthened by ion exchange, etc., and formed into thin glass articles.

[0009] According to aspect (1), a glass is provided. The glass comprises: 34 mol% or more and 65 mol% or less SiO2; 2 mol% or more and 25 mol% or less Al2O3; 1 mol% or more and 40 mol% or less MgO; 1 mol% or more and 10 mol% or less Na2O; and 3 mol% or more and 17 mol% or less Li2O. Here, the glass is substantially free of La2O3 and Y2O3 and has a Poisson ratio of 0.24 or more.

[0010] According to view (2), the glass of view (1) is provided, where the Poisson ratio is 0.25 or higher.

[0011] According to view (3), any one of view (1) to the aforementioned view is provided, where the Poisson ratio is 0.30 or less.

[0012] According to view (4), any one of view (1) to the aforementioned view is provided, where the Poisson ratio is 0.27 or less.

[0013] According to view (5), any one of view (1) to the aforementioned view is provided, and said glass contains 0 mol% or more and 16 mol% or less of B2O3.

[0014] According to view (6), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of B2O3.

[0015] According to view (7), any one of view (1) to view (5) is provided, and said glass contains 2 mol% or more and 16 mol% or less of B2O3.

[0016] According to view (8), any one of view (1) to the aforementioned view is provided, and said glass contains 0 mol% or more and 7 mol% or less of CaO.

[0017] According to view (9), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of CaO.

[0018] According to view (10), any one of view (1) to view (8) is provided, and said glass contains 1 mol% or more and 6 mol% or less of CaO.

[0019] According to view (11), any one of view (1) to the aforementioned view is provided, and said glass contains 0 mol% or more and 1 mol% or less of K2O.

[0020] According to view (12), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of K2O.

[0021] According to view (13), any one of view (1) to the aforementioned view is provided, and said glass contains 0 mol% or more and 0.2 mol% or less of SnO2.

[0022] According to view (14), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of SnO2.

[0023] According to view (15), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of SrO.

[0024] According to view (16), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of BaO.

[0025] According to view (17), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of HfO2.

[0026] According to view (18), any one of view (1) to the aforementioned view is provided, and said glass is substantially free of ZrO2.

[0027] According to view (19), any one of view (1) to the aforementioned view is provided, and said glass has a Young's modulus of 75 GPa or more and 105 GPa or less.

[0028] According to view (20), any one of view (1) to the aforementioned view is provided, and said glass has a shear modulus of 30 GPa or more and 41 GPa or less.

[0029] Additional features and advantages will be described in the following detailed description, which may be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments described herein, including the following detailed description, claims, and the attached drawings.

[0030] It should be understood that 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 characteristics of the claimed subject matter. The attached drawings are included to provide further understanding of the various embodiments and are incorporated into this specification to form part of this specification. The drawings illustrate the various embodiments described in this specification and serve to explain the principles and operations of the claimed subject matter together with the description. Brief explanation of the drawing

[0031] FIG. 1 is a schematic diagram illustrating a cross-section of glass having a compressive stress layer on its surface according to an embodiment disclosed and described herein; FIG. 2a is a plan view of an exemplary electronic device incorporating any glass article disclosed herein; and FIG. 2b is a perspective view of an exemplary electronic device of FIG. 2a. Specific details for implementing the invention

[0032] Now, lithium aluminosilicate glass will be referred to in detail according to various embodiments. Lithium aluminosilicate glass has excellent ion exchange properties, and chemical strengthening processes have been used to achieve high strength and high toughness properties in lithium aluminosilicate glass. Lithium aluminosilicate glass is a glass of high quality and high ion exchange properties. The substitution of Al2O3 into the silicate glass network increases the mutual diffusivity of monovalent cations during ion exchange. By chemical strengthening in a molten salt bath (e.g., KNO3 or NaNO3), glass with high strength, high toughness, and high indentation crack resistance can be achieved. The stress profile achieved through chemical strengthening can have various forms that improve the drop performance, strength, toughness, and other properties of the glass article.

[0033] Accordingly, lithium aluminosilicate glass, which possesses excellent physical properties, chemical durability, and ion exchangeability, is attracting attention for use as cover glass. In particular, lithium-containing aluminosilicate glass with higher fracture toughness and rapid ion exchangeability is provided herein. Through various ion exchange processes, greater center tension (CT), depth of compression (DOC), and high compressive stress (CS) can be achieved. However, the addition of lithium to aluminosilicate glass may reduce the melting point, softening point, or liquidus viscosity of the glass.

[0034] In embodiments of the glass compositions described herein, unless otherwise specified, the concentrations of constituent components (e.g., SiO2, Al2O3, Li2O, etc.) are given in molar percent (mol%) based on oxides. The constituent components of the alkali aluminosilicate glass compositions according to the embodiments are discussed individually below. It should be understood that any of the various listed ranges for one component may be individually combined with any of the various listed ranges for another component. A zero following a number used herein is intended to indicate the significant digit of the number. For example, the number "1.0" contains two significant digits, and the number "1.00" contains three significant digits.

[0035] Disclosed herein is a lithium aluminosilicate glass composition exhibiting a high Poisson ratio. In some embodiments, the glass composition is characterized by a Poisson ratio of 0.24 or higher.

[0036] The damage resistance of a material is generally a function of strength and toughness (or ductility). High strength prevents the introduction of new cracks, while high toughness hinders the propagation of existing cracks. To improve the damage resistance of silicate glass, two common approaches—external to atomic bonding or external to atomic structure—are widely used. The first external approach involves applying compressive stress to the glass surface, such as through ion exchange processes, differential CTE laminate structures, or thermal tempering methods. While this approach improves the strength of the glass, it can potentially increase its frangibility. Another widely used external approach is the fabrication of glass-polymer-glass laminate structures. If these laminates break, the ductile polymer holds the broken glass fragments together, preventing catastrophic fracture.

[0037] Another significantly different pathway inherent in the atomic bonding / structure of glass can also increase damage resistance. For example, boron-containing aluminosilicate glasses with maximized triple-coordinating boron content to introduce a 'floppy' mode and promote plastic / compressive deformation exhibit enhanced damage resistance. A similar approach is found in the design of Zr-based metallic glasses, where high fracture toughness (> 150 MPa√m) is achieved by maximizing local geometrically unstable structures to promote shear deformation. These approaches aim to increase fracture toughness by providing materials that exhibit ductile behavior.

[0038] The basis of brittle / ductile behavior is governed by the competition between shear and cleavage. At the crack tip, if the energy or stress required for shear is lower than the energy or stress required for cleavage, the crack tip is blunted by the shear, and consequently, the material will exhibit ductility or high fracture toughness. This fundamental approach can be applied to the intrinsic ductility of all types of glass.

[0039] At the atomic level, the brittle / ductile behavior of glass is governed by the competition between the bond strength and angular constraint of the glass network. A relative increase in bond strength or a relative decrease in angular constraint must prevent fracture or promote shear deformation to increase ductility. In addition to shear, compression can increase resistance to indentation or scratch, although compression may be less effective than shear under tensile loads. Therefore, adding specific types of metallic elements that bond strongly with oxygen and reduce angular constraint can increase toughness (ductility) without sacrificing strength (hardness).

[0040] As can be seen in Table 1, the binding energies for Ta, Th, Zr, La, Hf, Y, Ba, and B to oxygen are very high. The binding energies for oxygen are low for Na and K, which are typically contained in silicate glasses. Low binding energies can promote splitting or brittle fracture of the glass.

[0041] element Oxygen binding strength (kJ / mol) Si 800 Ta, Th 810 Zr 753 La 782 Hf 774 Y 714 Ba 561 B 782 Al 481 Ca 460 Mg 377 Na 272 K 339

[0042] Investigations into oxide glasses containing metal elements with high oxygen binding energies, such as Ta, La, Y, Ba, and Hf, have indicated that the "floppy" mode approach provides enhanced toughness. Previous investigations in compositional spaces containing Ta, La, Y, Ba, and Hf oxides have achieved clear glasses with a KIC of up to 1.2 MPa√m. Since there is currently no clear quantitative definition of the 'angular constraint' or 'directional flexibility' of atomic bonds, it can be difficult to distinguish glasses with excellent directional flexible bonds, particularly in glasses that do not contain expensive rare-earth oxides. It has been found that the Poisson ratio can serve as a rough guide for determining which materials will exhibit ductile behavior.

[0043] Modeling studies have demonstrated that the critical Poisson ratio for ductile behavior can vary depending on the system. For silicate systems, the critical Poisson ratio for producing ductile behavior is approximately 0.25. The glass compositions described herein have a higher Poisson ratio than conventional silicate glasses, which indicates that the glass has higher ductility and improved damage resistance.

[0044] While scratch resistance is desirable, drop performance is the most important characteristic for glass articles incorporated into mobile electronic devices. To improve drop performance on rough surfaces, fracture toughness and stress at depth are important. Furthermore, the selection of glass exhibiting ductile behavior also enhances drop performance. The glass composition space described herein was selected for its ability to achieve a high Poisson ratio.

[0045] In the glass compositions described herein, SiO2 is the largest component and is therefore the main component of the glass network formed from the glass composition. Pure SiO2 has a relatively low CTE. However, pure SiO2 has a high melting point. Therefore, if the concentration of SiO2 in the glass composition is too high, the formability of the glass composition may be reduced, as a higher concentration of SiO2 increases the melting point of the glass and this has an adverse effect on the formability of the glass. In embodiments, the glass composition generally comprises SiO2 of 34 mol% to 65 mol%, such as 35 mol% to 64 mol%, 36 mol% to 63 mol%, 37 mol% to 62 mol%, 38 mol% to 61 mol%, 39 mol% to 60 mol%, 40 mol% to 59 mol%, 41 mol% to 58 mol%, 42 mol% to 57 mol%, 43 mol% to 56 mol%, 44 mol% to 55 mol%, 45 mol% to 54 mol%, 46 mol% to 53 mol%, 47 mol% to 52 mol%, 48 mol% to 51 mol%, 49 mol% to 50 mol%, and all ranges and sub-ranges between the above values.

[0046] The glass composition contains Al2O3. Al2O3 can act as a glass network-forming agent similar to SiO2. Al2O3 can increase the viscosity of the glass composition due to tetrahedral coordination in the glass melt formed from the glass composition, and can reduce the formability of the glass composition when the amount of Al2O3 is excessive. However, if the concentration of Al2O3 is balanced with the concentrations of SiO2 and alkali oxides in the glass composition, Al2O3 can reduce the liquidus temperature of the glass melt, thereby improving liquidus viscosity and enhancing the compatibility of the glass composition with specific forming processes. In an embodiment, the glass composition generally comprises Al2O3 with a concentration of 2 mol% to 25 mol%, such as 3 mol% to 24 mol%, 4 mol% to 23 mol%, 5 mol% to 22 mol%, 6 mol% to 21 mol%, 7 mol% to 20 mol%, 8 mol% to 19 mol%, 9 mol% to 18 mol%, 10 mol% to 17 mol%, 11 mol% to 16 mol%, 12 mol% to 15 mol%, 13 mol% to 14 mol%, and all ranges and sub-ranges between the above values.

[0047] The glass composition contains Li2O. Including Li2O in the glass composition allows for better control of the ion exchange process and can further reduce the softening point of the glass, thereby increasing the manufacturability of the glass. The presence of Li2O in the glass composition can form a parabolic stress profile. In an embodiment, the glass composition contains an amount of Li2O of 3 mol% to 17 mol%, such as 4 mol% to 16 mol%, 5 mol% to 15 mol%, 6 mol% to 14 mol%, 7 mol% to 13 mol%, 8 mol% to 12 mol%, 9 mol% to 11 mol%, 10 mol% to 17 mol%, and all ranges and sub-ranges between the above values.

[0048] The glass composition also contains Na2O. Na2O helps the ion exchangeability of the glass composition and also improves the moldability, i.e., manufacturability, of the glass composition. However, if too much Na2O is added to the glass composition, the coefficient of thermal expansion (CTE) may become too low and the melting point too high. The inclusion of Na2O in the glass composition also makes it possible to achieve high compressive stress values ​​through enhanced ion exchange. In an embodiment, the glass composition contains an amount of Na2O of 1 mol% to 10 mol%, such as 1.5 mol% to 9.5 mol%, 2 mol% to 9 mol%, 2.5 mol% to 8.5 mol%, 3 mol% to 8 mol%, 3.5 mol% to 7.5 mol%, 4 mol% to 7 mol%, 4.5 mol% to 6.5 mol%, 5 mol% to 6 mol%, and all ranges and sub-ranges between the above values.

[0049] Glass contains MgO. The inclusion of MgO lowers the viscosity of the glass, which can improve its formability and manufacturability. The inclusion of MgO in the glass composition can also improve the deformation point and Young's modulus of the glass composition, as well as enhance the glass's ion exchange capacity. However, if too much MgO is added to the glass composition, the density and CTE of the glass composition increase undesirably. In an embodiment, the glass composition is 2 mol% or more and 39 mol% or less, 3 mol% or more and 38 mol% or less, 4 mol% or more and 37 mol% or less, 5 mol% or more and 36 mol% or less, 6 mol% or more and 35 mol% or less, 7 mol% or more and 34 mol% or less, 8 mol% or more and 33 mol% or less, 9 mol% or more and 32 mol% or less, 10 mol% or more and 31 mol% or less, 11 mol% or more and 30 mol% or less, 12 mol% or more and 29 mol% or less, 13 mol% or more and 28 mol% or less, 14 mol% or more and 27 mol% or less, 15 mol% or more and 26 mol% or less, 16 mol% or more and 25 mol% or less, 17 mol% or more and 24 mol% or less, 18 mol% or more and 23 mol% or less, 19 mol% or more and 22 mol% or less, 20 mol% or more and 21 mol% or less, and contains MgO in an amount of 1 mol% or more and 40 mol% or less, such as all ranges and sub-ranges between the above values.

[0050] The glass composition is substantially free of or without Y2O3. Y2O3 is a component that increases the cost of glass, and the availability of materials containing Y2O3 may be limited. The glass described herein can achieve the desired Poisson ratio and damage resistance without containing Y2O3. The term “substantially free” as used herein means that said component may be present in minute amounts as a contaminant, such as less than 0.01 mol% in the final glass, but is not added as a component of the batch material.

[0051] The glass composition is substantially non-existent of La2O3. La2O3 is a component that increases the cost of glass, and the availability of raw materials containing La2O3 may be limited. The glass described herein can achieve the desired Poisson ratio and damage resistance without containing La2O3.

[0052] Glass compositions may contain B2O3. The inclusion of B2O3 in glass provides enhanced scratch performance and increases the indentation fracture threshold of the glass. B2O3 in the glass composition also increases the fracture toughness of the glass. If the B2O3 content of the glass is too high, the maximum center tension achievable during ion exchange of the glass is reduced. Excessively high levels of B2O3 can also cause volatility issues during the glass melting and forming processes. In embodiments, the glass comprises B2O3 in an amount of 0 mol% to 16 mol%, such as greater than 0 mol% and less than or equal to 15 mol%, greater than or equal to 1 mol% and less than or equal to 1 mol%, greater than or equal to 2 mol% and less than or equal to 13 mol%, greater than or equal to 3 mol% and less than or equal to 12 mol%, greater than or equal to 4 mol% and less than or equal to 11 mol%, greater than or equal to 5 mol% and less than or equal to 10 mol%, greater than or equal to 6 mol% and less than or equal to 9 mol%, greater than or equal to 7 mol% and less than or equal to 8 mol%, greater than or equal to 2 mol% and less than or equal to 16 mol%, and all ranges and sub-ranges between the above values. In embodiments, the glass composition is substantially non-existent of B2O3.

[0053] The glass composition may contain CaO. The inclusion of CaO lowers the viscosity of the glass, which improves formability, deformation point, and Young's modulus, and can improve ion exchange capacity. However, if too much CaO is added to the glass composition, the density and CTE of the glass composition increase. In an embodiment, the glass composition contains CaO in an amount of 0 mol% to 7 mol%, such as greater than 0 mol% and less than or equal to 6.5 mol%, greater than 0.5 mol% and less than or equal to 6 mol%, greater than 1 mol% and less than or equal to 5.5 mol%, greater than 1.5 mol% and less than or equal to 5 mol%, greater than 2 mol% and less than or equal to 4.5 mol%, greater than 2.5 mol% and less than or equal to 4 mol%, greater than 3 mol% and less than or equal to 4 mol%, greater than 3.5 mol% and less than or equal to 7 mol%, greater than 1 mol% and less than or equal to 6 mol%, and all ranges and sub-ranges between the above values. In an embodiment, the glass composition is substantially free of or has no CaO.

[0054] The glass composition may contain K2O. The inclusion of a small amount of K2O in the glass can improve the ion exchange efficiency of the glass. In embodiments, the glass composition contains K2O in an amount of 0 mol% to 1 mol%, such as greater than 0 mol% and less than or equal to 1.0 mol%, greater than or equal to 0.1 mol% and less than or equal to 0.9 mol%, greater than or equal to 0.2 mol% and less than or equal to 0.8 mol%, greater than or equal to 0.3 mol% and less than or equal to 0.7 mol%, greater than or equal to 0.4 mol% and less than or equal to 0.6 mol%, greater than or equal to 0.5 mol% and less than or equal to 1.0 mol%, and all ranges and sub-ranges between the above values. In embodiments, the glass composition may be substantially free of K2O or may be free of it.

[0055] The glass composition may optionally include one or more clarifying agents. In embodiments, the clarifying agent may include, for example, SnO2. In some embodiments, SnO2 may be present in the glass composition in an amount of 0.2 mol% or less, such as 0.1 mol% or less, 0 mol% or more and 0.2 mol% or less, 0 mol% or more and 0.1 mol% or less, 0 mol% or more and 0.05 mol% or less, 0.1 mol% or more and 0.2 mol% or less, and all ranges and sub-ranges between said values. In some embodiments, the glass composition may be substantially free of SnO2 or may be free of it. In some embodiments, the glass composition may be substantially free of one or both of arsenic and antimony. In other embodiments, the glass composition may be free of one or both of arsenic and antimony.

[0056] In embodiments, the glass composition may substantially lack or be absent of at least one of ZrO2, SrO, BaO, and HfO2. In embodiments, the glass composition may substantially lack or be absent of ZrO2. In embodiments, the glass composition may substantially lack or be absent of SrO. In embodiments, the glass composition may substantially lack or be absent of BaO. In embodiments, the glass composition may substantially lack or be absent of HfO2.

[0057] In embodiments, the glass composition may be substantially free of or free of TiO2. The inclusion of TiO2 in the glass composition may cause the glass to become prone to devitrification and / or exhibit undesirable coloring.

[0058] In an embodiment, the glass composition may be substantially free of or may not contain P2O5. The inclusion of P2O5 in the glass composition may undesirably reduce the meltability and moldability of the glass composition, thereby impairing the manufacturability of the glass composition. It is not necessary to include P2O5 in the glass composition described herein to achieve the desired ion exchange performance. For this reason, P2O5 may be excluded from the glass composition so as not to negatively affect the manufacturability of the glass composition while maintaining the desired ion exchange performance.

[0059] In embodiments, the glass composition may be substantially free of Fe2O3. Iron is often present in the raw materials used to form the glass composition and, as a result, may be detected in the glass composition described herein even if it is not actively added to the glass batch.

[0060] Now, the physical properties of the glass composition disclosed above will be discussed.

[0061] The glass composition described herein has a high Poisson ratio. As previously mentioned, a high Poisson ratio of the glass composition exhibits ductile behavior that increases the damage resistance of the glass. In an embodiment, the Poisson ratio of the glass composition is 0.24 or higher, such as 0.25 or higher, 0.26 or higher, 0.27 or higher, 0.28 or higher, 0.29 or higher, or higher. In an embodiment, the Poisson ratio of the glass composition is 0.30 or lower, such as 0.29 or lower, 0.28 or lower, 0.27 or lower, 0.26 or lower, 0.25 or lower, or lower. In an embodiment, the Poisson ratio of the glass composition is 0.24 or higher, such as 0.25 or higher, 0.29 or lower, 0.26 or higher, 0.28 or lower, 0.25 or higher, 0.27 or lower, and all ranges and sub-ranges between the above values. The Poisson ratio values ​​mentioned in this disclosure refer to values ​​measured by a general type of resonant ultrasound spectroscopy specified in ASTM E2001-13, titled "Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts."

[0062] In embodiments, the Young's modulus (E) of the glass composition is 75 GPa or greater, such as 80 GPa or greater, 90 GPa or greater, 95 GPa or greater, 100 GPa or greater, or greater. In embodiments, the Young's modulus (E) of the glass composition may be 75 GPa or greater and 105 GPa or less, such as 80 GPa or greater and 100 GPa or less, 85 GPa or greater and 95 GPa or less, 90 GPa or greater and 105 GPa or less, and all ranges and sub-ranges between the above values. The Young's modulus values ​​cited in this disclosure represent values ​​measured by a general type of resonant ultrasound spectroscopy specified in ASTM E2001-13 titled "Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts."

[0063] In embodiments, the glass composition has a shear modulus (G) of 30 GPa or more, such as 31 GPa or more, 32 GPa or more, 33 GPa or more, 34 GPa or more, 35 GPa or more, 36 GPa or more, 37 GPa or more, 38 GPa or more, 39 GPa or more, 40 GPa or more, or more. In embodiments, the glass composition may have a shear modulus (G) of 30 GPa or more and 41 GPa or less, such as 31 GPa or more and 40 or less, 32 GPa or more and 39 or less, 33 GPa or more and 38 or less, 34 GPa or more and 37 or less, 35 GPa or more and 36 or less, and all ranges and sub-ranges between the above values. The shear modulus values ​​cited in this disclosure represent values ​​measured by a general type of resonant ultrasound spectroscopy specified in ASTM E2001-13, titled "Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts."

[0064] From the above composition, a glass article according to an embodiment can be formed by any suitable method. In an embodiment, the glass composition can be formed by a rolling process.

[0065] Glass compositions and articles manufactured therefrom may be characterized by the manner in which they are formed. For example, a glass composition may be characterized as float-formable (i.e., formed by a float process) or roll-formable (i.e., formed by a rolling process).

[0066] In one or more embodiments, the glass composition described herein may form a glass article exhibiting an amorphous microstructure and may be substantially free of crystals or crystallites. In other words, a glass article formed from the glass composition described herein may exclude glass-ceramic materials.

[0067] As described above, in an embodiment, the glass composition described herein may be strengthened by ion exchange, etc., and may produce a glass article that is damage-resistant for applications such as display covers, but is not limited thereto. Referring to FIG. 1, a glass article is illustrated having a first region under compressive stress extending from the surface of the glass article to a depth of compression (DOC) (e.g., first and second compression layers (120, 122) of FIG. 1) and a second region under tensile stress or central tension (CT) extending from the DOC to the center or internal region of the glass article (e.g., central region (130) of FIG. 1). As used herein, DOC represents the depth at which stress within the glass article changes from compression to tension. At the DOC, stress represents a stress value of 0 as it intersects from positive (compressive) stress to negative (tensile) stress.

[0068] According to the convention generally used in the art, compression or compressive stress is expressed as a negative (< 0) stress, and tensile or tensile stress is expressed as a positive (> 0) stress. However, throughout this description, CS is expressed as a positive or absolute value—that is, as cited herein, CS = |CS|. Compressive stress (CS) has a maximum value at or near the surface of the glass article, and CS varies by a distance d from the surface according to a function. Referring again to FIG. 1, the first segment (120) extends from the first surface (110) to a depth (d1), and the second segment (122) extends from the second surface (112) to a depth (d2). Together, these segments define the compression or CS of the glass article (100). Compressive stress (including surface CS) can be measured with a surface stress meter (FSM) using a commercially available measuring instrument, such as the FSM-6000 manufactured by Orihara Industry Co., Ltd. (Japan). Surface stress measurement relies on the accurate measurement of the stress-optical coefficient (SOC) associated with the birefringence of the glass. The SOC is measured according to Procedure C (the glass disk method) described in ASTM Standard C770-16, titled "Standard Test Method for Measurement of Glass Stress-Optical Coefficient," the full details of which are incorporated herein by reference.

[0069] In an embodiment, the compressive stress layer is 425 MPa or more and 1150 MPa or less, 450 MPa or more and 1100 MPa or less, 475 MPa or more and 1050 MPa or less, 500 MPa or more and 1000 MPa or less, 525 MPa or more and 975 MPa or less, 550 MPa or more and 950 MPa or less, 575 MPa or more and 925 MPa or less, 600 MPa or more and 900 MPa or less, 625 MPa or more and 875 MPa or less, 650 MPa or more and 850 MPa or less, 675 MPa or more and 825 MPa or less, 700 MPa or more and 800 MPa or less, 725 MPa or more and 775 MPa or less, 750 MPa or more and 1200 MPa or less, 550 MPa or more and 925 MPa or less, and all ranges between the above values ​​and It includes a CS of 400 MPa or more and 1200 MPa or less, such as a sub-range. In an embodiment, the compressive stress layer includes a CS of 400 MPa or more, such as 450 MPa or more, 500 MPa or more, 550 MPa or more, 600 MPa or more, 650 MPa or more, 700 MPa or more, 750 MPa or more, 800 MPa or more, 850 MPa or more, 900 MPa or more, or more.

[0070] In one or more embodiments, Na + and K + Ions are exchanged into the glass article, and Na + The ion is K + It diffuses to deeper depths within the glass article than ions. K + Ion penetration depth ("DOL KPotassium DOL is distinguished from DOC as it represents the potassium penetration depth as a result of the ion exchange process. Potassium DOL is generally lower than the DOC of the articles described herein. Potassium DOL is measured using a surface stress meter, such as the commercially available FSM-6000 surface stress meter manufactured by Orihara Industrial Co., Ltd. (Japan), which relies on the accurate measurement of the stress optical factor (SOC), as described above in relation to CS measurement. Potassium DOL (DOL K ) is a compressive stress spike (DOL) where the stress profile transitions from a steep spike region to a less steep deep region. SP The depth of ) can be defined. The deep region extends from the bottom of the spike to the depth of compression. In an embodiment, the DOL of the glass article K may be 4 μm or more and 11 μm or less, such as 5 μm or more and 10 μm or less, 6 μm or more and 9 μm or less, 7 μm or more and 8 μm or less, and all ranges and sub-ranges between the above values. In an embodiment, the DOL of the glass article K may be 4 μm or more, such as 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, or greater than or equal to 5 μm. In an embodiment, the DOL of the glass article K It may be 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, or 11 μm or less.

[0071] The compressive stress on both main surfaces (110, 112 in FIG. 1) is balanced by the stored tension in the central region (130) of the glass article. The maximum central tension (CT) and DOC values ​​can be measured using scattering light polarization (SCALP) techniques known in the art. The refractive near-field (RNF) method or SCALP can be used to determine the stress profile of the glass article. When the RNF method is used to measure the stress profile, the maximum CT value provided by SCALP is used in the RNF method. In particular, the stress profile determined by RNF balances the forces and is corrected by the maximum CT value provided by the SCALP measurement. The RNF method is described in U.S. Patent No. 8,854,623 titled “Systems and methods for measuring a profile characteristic of a glass sample,” which is incorporated herein by reference in its entirety. In particular, the RNF method comprises placing a glass article adjacent to a reference block, generating a polarization-switched light beam that switches between orthogonal polarizations at speeds between 1 Hz and 50 Hz, measuring the power of the polarization-switched light beam, and generating a polarization-switched reference signal, wherein the power measured at each orthogonal polarization is within 50% of each other. The method further comprises transmitting the polarization-switched light beam to the glass sample through a reference block of different depths and then relaying the transmitted polarization-switched light beam to a signal photodetector using a relay optical system, wherein the signal photodetector generates a polarization-switched detector signal. The method also comprises splitting the detector signal into the reference signal to form a normalized detector signal and determining the profile characteristics of the glass sample from the normalized detector signal.

[0072] The amount of maximum center tension of a glass article indicates the degree of strengthening produced through the ion exchange process, and a higher maximum CT value is associated with an increased degree of strengthening. If the maximum CT value is too high, the glass article may exhibit undesirable brittle behavior. In an embodiment, the glass article may have a maximum CT of 90 MPa or more, such as 95 MPa or more, 100 MPa or more, 105 MPa or more, 110 MPa or more, 115 MPa or more, 120 MPa or more, 125 MPa or more, 130 MPa or more, 135 MPa or more, 140 MPa or more, 145 MPa or more, 150 MPa or more, 155 MPa or more, or more. In an embodiment, the glass article may have a maximum CT of 90 MPa to 160 MPa, such as 95 MPa to 155 MPa, 100 MPa to 150 MPa, 105 MPa to 145 MPa, 110 MPa to 140 MPa, 115 MPa to 135 MPa, 120 MPa to 130 MPa, 125 MPa to 160 MPa, 100 MPa to 160 MPa, and all ranges and sub-ranges between the above values.

[0073] In some embodiments of this specification, the DOC is provided as part of the thickness (t) of the glass article. In an embodiment, the glass article may have a depth of compression (DOC) of 0.15 t to 0.25 t, such as 0.18 t to 0.22 t, or 0.19 t to 0.21 t, and all ranges and sub-ranges between said values.

[0074] A compressive stress layer can be formed on glass by exposing the glass to an ion exchange medium. In an embodiment, the ion exchange medium may be molten nitrate. In an embodiment, the ion exchange medium may be a molten salt bath, and KNO3, It may include NaNO3, or a combination thereof. In an embodiment, the ion exchange medium may contain an amount of KNO3 of 95 wt% or less, such as 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, or less. In an embodiment, the ion exchange medium may contain an amount of KNO3 of 75 wt% or more, such as 80 wt% or more, 85 wt% or more, 90 wt% or more, 95 wt% or more, or more. In an embodiment, the ion exchange medium may contain an amount of KNO3 of 75 wt% or more, such as 80 wt% or more and 90 wt% or less, 75 wt% or more and 85 wt% or less, and all ranges and sub-ranges between the above values. In an embodiment, the ion exchange medium may contain an amount of NaNO3 of 25 wt% or less, such as 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or less, or less. In an embodiment, the ion exchange medium may contain an amount of NaNO3 of 5 wt% or more, such as 10 wt% or more, 15 wt% or more, 20 wt% or more, or more. In an embodiment, the ion exchange medium may contain an amount of NaNO3 of 5 wt% or more, such as 10 wt% or more and 20 wt% or less, 15 wt% or more and 25 wt% or less, and all ranges and sub-ranges between the above values. It should be understood that the ion exchange medium may be defined by any combination of the aforementioned ranges. In an embodiment, other sodium and potassium salts may be used in the ion exchange medium, such as sodium or potassium nitrite, phosphate, or sulfate. In an embodiment, the ion exchange medium may include a lithium salt, such as LiNO3. The ion exchange medium may additionally include an additive that is typically included when ion-exchanging glass, such as silica.

[0075] A glass composition may be exposed to an ion exchange medium by immersing a glass substrate made of the glass composition in a bath of an ion exchange medium, spraying the ion exchange medium onto a glass substrate made of the glass composition, or otherwise physically applying the ion exchange medium to a glass substrate made of the glass composition, thereby forming an ion-exchanged glass article. When exposed to the glass composition, the ion exchange medium may be at a temperature of 360°C to 500°C, such as 370°C to 490°C, 380°C to 480°C, 390°C to 470°C, 400°C to 460°C, 410°C to 450°C, 420°C to 440°C, 430°C to 470°C, 430°C to 450°C, and all ranges and sub-ranges between the above values, depending on the embodiment. In an embodiment, the glass composition may be exposed to an ion exchange medium for 4 hours or more and 48 hours or less, such as 4 hours or more and 24 hours or less, 8 hours or more and 44 hours or less, 12 hours or more and 40 hours or less, 16 hours or more and 36 hours or less, 20 hours or more and 32 hours or less, 24 hours or more and 28 hours or less, 4 hours or more and 12 hours or less, and all ranges and sub-ranges between the above values.

[0076] The ion exchange process may be performed in an ion exchange medium under processing conditions that provide an enhanced compressive stress profile, for example, as disclosed in U.S. Patent Application Publication No. 2016 / 0102011, incorporated by reference throughout this specification. In some embodiments, the ion exchange process may be selected to form a parabolic stress profile in a glass article, such as the stress profile described in U.S. Patent Application Publication No. 2016 / 0102014, incorporated by reference throughout this specification.

[0077] It should be understood that after the ion exchange process is performed, the composition on the surface of the ion-exchanged glass article differs from the composition of the glass substrate as formed (i.e., the glass substrate before the ion exchange process). This is, for example, Li + or Na + Alkali metal ions of a type of glass substrate formed as such, respectively, e.g., Na + or K + This is the result of replacement with larger alkali metal ions, such as those. However, in embodiments, the glass composition at or near the center of depth of the glass article still has the composition of the non-ion-exchanged glass substrate as formed and can be used to form the glass article. As utilized herein, the center of the glass article refers to any location of the glass article at a distance of at least 0.5t from all surfaces of the glass article, where t refers to the thickness of the glass article.

[0078] The glass articles disclosed herein may be incorporated into other articles such as articles having a display (or display articles) (e.g., consumer electronics including mobile phones, tablets, computers, navigation systems, etc.), construction articles, transport articles (e.g., automobiles, trains, aircraft, ships, etc.), home appliances, or any articles requiring transparency, scratch resistance, wear resistance, or a combination thereof. An exemplary article incorporating any of the glass articles disclosed herein is illustrated in FIGS. 2a and 2b. Specifically, FIGS. 2a and 2b show a consumer electronic device (200) comprising: a housing (202) having a front (204), a rear (206), and a side (208); an electrical component (not shown) that is at least partially inside or entirely within the housing and includes at least a controller, memory, and a display (210) on the front of the housing or adjacent thereto; and a cover (212) on the front of the housing or above it so as to be placed over the display. In an embodiment, at least one part of at least one of the cover (212) and the housing (202) may include any of the glass articles described herein.

[0079] Examples

[0080] The embodiments will become more clear through the following examples. It should be understood that these examples are not limited to the embodiments described above.

[0081] A glass composition was prepared and analyzed. The analyzed glass composition contains the components listed in Table 2 below and was prepared by a conventional glass molding method. In Table 2, all components are in mol%, and the Poisson ratio (ν), Young's modulus (E), and shear modulus (G) of the glass composition were measured according to the method disclosed herein.

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] All compositional components, relationships, and ratios described herein are provided in mol% unless otherwise specified. All ranges disclosed herein include all ranges and sub-ranges covered by the broadly disclosed ranges, regardless of whether they were explicitly mentioned before or after the ranges were disclosed.

[0092] It will be apparent to those skilled in the art that various modifications and variations may be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Accordingly, this specification is intended to include modifications and variations of the various embodiments described herein, provided that such modifications and variations fall within the scope of the appended claims and equivalents.

Claims

Claim 1 A glass comprising 34 mol% or more and 65 mol% or less SiO2; 2 mol% or more and 25 mol% or less Al2O3; 5.8 mol% or more and 15.9 mol% or less B2O3; at least one of 5.8 mol% or more and 36 mol% or less MgO or 8 mol% or more and 15.9 mol% or less B2O3; 1 mol% or more and 10 mol% or less Na2O; and 3 mol% or more and 17 mol% or less Li2O, wherein the sum of Al2O3 and MgO is 22.6 mol% or more and 40.3 mol% or less, and the sum of B2O3, Al2O3 and MgO is 32.7 mol% or more and 51.7 mol% or less, wherein the glass comprises less than 0.01 mol% of La2O3 and Y2O3, and has a Poisson ratio of 0.25 or more. Claim 2 The glass of claim 1, wherein the Poisson ratio is 0.27 or less. Claim 3 Glass according to claim 1 or 2, wherein the Poisson ratio is 0.30 or less. Claim 4 The glass according to claim 1 or 2, wherein the glass comprises 0 mol% or more and 7 mol% or less of CaO. Claim 5 The glass according to claim 1 or 2, wherein the glass comprises 1 mol% or more and 6 mol% or less of CaO. Claim 6 The glass according to claim 1 or 2, wherein the glass comprises 0 mol% or more and 1 mol% or less of K2O. Claim 7 The glass according to claim 1 or 2, wherein the glass comprises 0 mol% or more and 0.2 mol% or less of SnO2. Claim 8 The glass of claim 1 or 2, wherein the glass comprises less than 0.01 mol% of at least one of the following: CaO, K2O, SnO2, SrO, BaO, HfO2 and ZrO2. Claim 9 The glass of claim 1 or 2, wherein the glass has a Young's modulus of 75 GPa or more and 105 GPa or less. Claim 10 The glass according to claim 1 or 2, wherein the glass has a shear modulus of 30 GPa or more and 41 GPa or less. Claim 11 The glass of claim 1 or 2, wherein the glass comprises 8.3 mol% or more of B2O3. Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete

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