Transparent β-quartz glass ceramics

Abstract

A transparent β-quartz glass ceramic is provided. The glass ceramic comprises a primary crystalline phase comprising a β-quartz solid solution, a secondary crystalline phase comprising tetragonal ZrO2, and an amorphous phase of lithium aluminosilicate. The glass ceramic can be ion exchanged using a molten nitrate bath. A method for producing the glass ceramic is also provided.

Description

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 119,072, filed on November 30, 2020, the contents of which are hereby incorporated by reference in their entirety. Technical Field

[0002] The present disclosure relates generally to transparent glass-ceramic compositions and, more particularly, to transparent beta-quartz glass-ceramics that can be formed into cover glasses or housings for electronic devices. Background Art

[0003] Portable electronic devices, such as smartphones, tablet computers, and wearable devices (e.g., watches and fitness trackers), continue to become smaller and more complex. Consequently, the materials typically used on at least one exterior surface of such portable electronic devices also continue to become more complex. For example, as portable electronic devices become smaller and thinner to meet consumer demand, the display covers and housings used in these portable electronic devices also become smaller and thinner, leading to higher performance requirements for the materials used to form these components.

[0004] Glass-ceramic materials with high transparency are attractive for such applications due to their high mechanical strength. Exemplary glass-ceramic materials are those that contain a β-quartz solid solution crystalline phase and exhibit high transparency. β-quartz solid solution glass-ceramics that include magnesium in the crystalline phase can be chemically strengthened by ion exchange. Ion exchange occurs as lithium ions in the molten salt bath exchange with magnesium ions in the β-quartz solid solution crystalline phase. Due to the Mg 2+ The mobility of ions is increased, so a high temperature bath (>700°C) is required. Such a high temperature bath is expensive.

[0005] Therefore, there is a need for β-quartz solid solution glass-ceramic materials that can be strengthened by low-cost means. Summary of the Invention

[0006] According to aspect (1), a glass ceramic product is provided. The glass ceramic product comprises: a primary crystalline phase comprising a β-quartz solid solution; a secondary crystalline phase comprising tetragonal ZrO2; and a lithium aluminosilicate amorphous phase, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.3, R2O is Li2O+Na2O+K2O+Cs2O+Rb2O, and R'O is MgO+CaO+SrO+BaO+ZnO.

[0007] According to aspect (2), there is provided the glass ceramic article of aspect (1), wherein the crystallinity of the glass ceramic is greater than 50 wt%.

[0008] According to aspect (3), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, wherein the grain size of the main crystalline phase is greater than or equal to 50 nm and less than or equal to 100 nm.

[0009] According to aspect (4), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, wherein the glass ceramic has a transmittance greater than or equal to 90% in the wavelength range of 400 nm to 750 nm at a thickness of 0.8 mm.

[0010] According to aspect (5), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 65 mol % and less than or equal to 80 mol % SiO 2 .

[0011] According to aspect (6), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 8 mol % and less than or equal to 20 mol % Al 2 O 3 .

[0012] According to aspect (7), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 4 mol % and less than or equal to 18 mol % MgO.

[0013] According to aspect (8), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 0 mol % and less than or equal to 4 mol % ZnO.

[0014] According to aspect (9), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 1 mol % and less than or equal to 4 mol % ZrO 2 .

[0015] According to aspect (10), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 0 mol % and less than or equal to 0.4 mol % SnO 2 .

[0016] According to aspect (11), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 0 mol % and less than or equal to 1 mol % TiO 2 .

[0017] According to aspect (12), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, wherein the glass ceramic is substantially free of TiO2.

[0018] According to aspect (13), there is provided a glass ceramic article of any one of aspects (1) to the previous aspects, wherein the glass ceramic is substantially free of Bi2O3 and B2O3.

[0019] According to aspect (14), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.1.

[0020] According to aspect (15), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, wherein the molar ratio (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.0.

[0021] According to aspect (16), there is provided a glass ceramic article of any one of aspects (1) to the previous aspects, comprising greater than or equal to 2 mol % and less than or equal to 8 mol % Li2O.

[0022] According to aspect (17), a glass ceramic article of any one of aspects (1) to the previous aspects is provided, comprising: greater than or equal to 0 mol % and less than or equal to 5 mol % Na2O; and greater than or equal to 0 mol % and less than or equal to 5 mol % K2O.

[0023] According to aspect (18), there is provided the glass ceramic article of any one of aspects (1) to the previous aspects, comprising a compressive stress layer extending from the surface to a compression depth.

[0024] According to aspect (19), there is provided the glass ceramic article of aspect (18), wherein the compression depth is greater than or equal to 10 μm.

[0025] According to aspect (20), there is provided a glass ceramic article according to any one of aspects (18) to the previous aspects, wherein the compression depth is less than or equal to 60 μm.

[0026] According to aspect (21), the glass ceramic article of aspect (18) to any one of the previous aspects is provided, wherein the compression depth is less than or equal to 0.2t, where t is the thickness of the glass ceramic article.

[0027] According to aspect (22), there is provided the glass ceramic article of aspect (18) to any one of the previous aspects, wherein the compressive stress layer comprises a compressive stress greater than or equal to 100 MPa.

[0028] According to aspect (23), a consumer electronic product is provided. The consumer electronic product comprises: a housing comprising a front surface, a rear surface, and side surfaces; an electrical component at least partially located within the housing, the electrical component comprising a controller, a memory, and a display, the display being located at or adjacent to the front surface of the housing; and a cover substrate disposed above the display; wherein at least a portion of at least one of the housing or the cover substrate comprises the glass-ceramic article of any one of aspects (1) to the preceding aspects.

[0029] According to aspect (24), a method for producing a glass ceramic article is provided. The method comprises the following steps: nucleating a glass substrate to form a nucleated glass substrate; ceramizing the nucleated glass substrate to form a glass ceramic article, wherein the glass substrate comprises lithium aluminosilicate, and the glass ceramic article comprises: a primary crystalline phase comprising a β-quartz solid solution; a secondary crystalline phase comprising tetragonal ZrO2; and an amorphous lithium aluminosilicate phase, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.3, R2O is Li2O+Na2O+K2O+Cs2O+Rb2O, and R'O is MgO+CaO+SrO+BaO+ZnO.

[0030] According to aspect (25), there is provided the method of aspect (24), wherein the nucleation step comprises treatment in an environment at a temperature greater than or equal to 700°C and less than or equal to 800°C.

[0031] According to aspect (26), the method of any one of aspects (24) to the previous aspects is provided, wherein the nucleation step lasts for a time greater than or equal to 10 minutes and less than or equal to 12 hours.

[0032] According to aspect (27), there is provided the method of any one of aspects (24) to the previous aspects, wherein the ceramizing step comprises treatment in an environment at a temperature greater than or equal to 900°C and less than or equal to 1000°C.

[0033] According to aspect (28), the method of any one of aspects (24) to the previous aspects is provided, wherein the ceramizing step lasts for a time greater than or equal to 10 minutes and less than or equal to 4 hours.

[0034] According to aspect (29), a method according to aspect (24) to any of the previous aspects is provided, further comprising an intermediate heat treatment of the nucleated glass substrate, wherein the intermediate heat treatment is performed after the nucleation step and before the ceramicization step, and comprises treatment in an environment at a temperature higher than the nucleation step and lower than the ceramicization step.

[0035] According to aspect (30), there is provided the method of aspect (29), wherein the intermediate heat treatment comprises treatment in an environment at a temperature greater than or equal to 800°C and less than or equal to 900°C.

[0036] According to aspect (31), the method of any one of aspects (29) to the previous aspects is provided, wherein the intermediate heat treatment lasts for a time greater than or equal to 10 minutes and less than or equal to 4 hours.

[0037] According to aspect (32), the method of aspect (24) to any one of the previous aspects is provided, further comprising the step of: performing ion exchange on the glass ceramic article in a molten salt bath, wherein the molten salt bath comprises NaNO3, KNO3, or a combination thereof.

[0038] According to aspect (33), there is provided the method of aspect (32), wherein the temperature of the molten salt bath is greater than or equal to 350°C and less than or equal to 550°C.

[0039] According to aspect (34), the method of any one of aspects (32) to the previous aspects is provided, wherein the ion exchange is continued for a time greater than or equal to 30 minutes and less than or equal to 24 hours.

[0040] According to aspect (35), a method of aspect (24) to any one of the previous aspects is provided, wherein the glass substrate comprises: greater than or equal to 65 mol% and less than or equal to 80 mol% SiO2; greater than or equal to 8 mol% and less than or equal to 20 mol% Al2O3; greater than or equal to 2 mol% and less than or equal to 8 mol% Li2O; greater than or equal to 4 mol% and less than or equal to 18 mol% MgO; greater than or equal to 0 mol% and less than or equal to 4 mol% ZnO; greater than or equal to 1 mol% and less than or equal to 4 mol% ZrO2; greater than or equal to 0 mol% and less than or equal to 0.4 mol% SnO2, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.3.

[0041] According to aspect (36), the method of any one of aspects (24) to the previous aspects is provided, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.1.

[0042] According to aspect (37), a method of aspect (24) to any one of the previous aspects is provided, wherein the glass substrate comprises: greater than or equal to 0 mol% and less than or equal to 1 mol% TiO2, wherein the glass substrate is substantially free of Bi2O3 and B2O3.

[0043] According to aspect (38), a glass is provided. The glass comprises: greater than or equal to 65 mol% and less than or equal to 80 mol% SiO2; greater than or equal to 8 mol% and less than or equal to 20 mol% Al2O3; greater than or equal to 2 mol% and less than or equal to 8 mol% Li2O; greater than or equal to 4 mol% and less than or equal to 18 mol% MgO; greater than or equal to 0 mol% and less than or equal to 4 mol% ZnO; greater than or equal to 1 mol% and less than or equal to 4 mol% ZrO2; greater than or equal to 0 ... or equal to 0 mol % and less than or equal to 0.4 mol % SnO2; greater than or equal to 0 mol % and less than or equal to 1 mol % TiO2; wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.3, R2O is Li2O+Na2O+K2O+Cs2O+Rb2O, R'O is MgO+CaO+SrO+BaO+ZnO, and the glass is substantially free of Bi2O3 and B2O3.

[0044] According to aspect (39), the glass of aspect (38) is provided, wherein the glass is substantially free of TiO2.

[0045] According to aspect (40), the glass of aspect (38) to any one of the previous aspects is provided, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.1.

[0046] According to aspect (41), the glass of aspect (38) to any one of the previous aspects is provided, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.0.

[0047] According to aspect (42), the glass of aspect (38) to any one of the previous aspects is provided, comprising greater than or equal to 0 mol % and less than or equal to 5 mol % Na2O.

[0048] According to aspect (43), the glass of aspect (38) to any one of the previous aspects is provided, comprising greater than or equal to 0 mol % and less than or equal to 5 mol % K2O.

[0049] Additional features and advantages will be described in the detailed description that follows, and those skilled in the art may understand the additional features and advantages in part from that description, or may learn the additional features and advantages by practicing the embodiments described herein, including the detailed description that follows, the claims, and the drawings.

[0050] It should 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 operation of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 schematically illustrates a cross-section of a glass-ceramic having a compressive stress layer on its surface according to embodiments described and illustrated herein;

[0052] Figure 2A is a plan view of an exemplary electronic device incorporating any of the glass-ceramic articles disclosed herein;

[0053] Figure 2B for Figure 2A A perspective view of an exemplary electronic device;

[0054] Figure 3 is an X-ray diffraction analysis of the glass-ceramic product according to the embodiment;

[0055] Figure 4 is a scanning electron microscope image of a glass-ceramic article according to an embodiment;

[0056] Figure 5 for Figure 4 Scanning electron microscope images of glass-ceramic products at higher magnifications;

[0057] Figure 6 is a graph of measured transmittance as a function of wavelength for glass-ceramic articles according to embodiments;

[0058] Figure 7 is a graph of NaO concentration as a function of depth below the surface of an ion-exchanged glass-ceramic article according to an embodiment;

[0059] Figure 8 is a Weibull plot of ring-on-ring strength of a non-ion-exchanged glass-ceramic article and an ion-exchanged glass-ceramic article according to an embodiment; and

[0060] Figure 9 Schematic diagram of the ring-to-ring test equipment. DETAILED DESCRIPTION

[0061] Transparent β-quartz glass-ceramics according to various embodiments will now be described in detail. More specifically, the transparent β-quartz glass-ceramics can be ion-exchanged using a molten nitrate bath. Therefore, the transparent magnesite spinel glass-ceramics are suitable for use in display covers and housings for portable electronic devices.

[0062] In the following description, in the several views shown in the accompanying drawings, the same reference numerals represent the same or corresponding parts. It should also be understood that, unless otherwise specified, terms such as "top", "bottom", "outward", "inward" and the like are convenient words and should not be interpreted as restrictive terms. Whenever a group is described as consisting of at least one of a group of elements or their combinations, it should be understood that the group can be composed of any number of those elements alone or in combination with each other. Unless otherwise specified, when stated, the range of values ​​includes the upper and lower limits of the range and any range therebetween. The indefinite articles "one", "an" and the corresponding definite articles "the" used herein mean "at least one" or "one or more", unless otherwise specified. It should also be understood that the various features disclosed in the specification and the drawings can be used in any and all combinations.

[0063] Unless otherwise stated, all compositions of the glasses described herein are expressed in mole percent (mol %), and the components are provided on an oxide basis. Unless otherwise stated, all temperatures are expressed in degrees Celsius (° C.).

[0064] It should be noted that the terms "substantially" and "about" may be used herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. For example, a composition that is "substantially free of K2O" is one in which K2O is not actively added or formulated into the composition, but may be present in very small amounts (e.g., in an amount of less than about 0.01 mol%) as a contaminant. As used herein, when the term "about" is used to modify a value, the exact value is also disclosed.

[0065] The glass-ceramics described herein comprise a primary crystalline phase, a secondary crystalline phase, and a residual amorphous (glass) phase. The primary crystalline phase is the predominant crystalline phase and is defined herein as the crystalline phase that accounts for the largest portion of the glass-ceramic by weight. Thus, the amount of the secondary crystalline phase present in the glass-ceramic can be less than the amount of the primary crystalline phase, and the amount of the crystalline phase of the glass-ceramic can be described by weight percentage of the glass-ceramic. In some embodiments, the glass-ceramic can include additional crystalline phases such that the glass-ceramic includes more than two crystalline phases.

[0066] In embodiments, the primary crystalline phase comprises a β-quartz solid solution. A β-quartz solid solution is a β-quartz crystal structure "filled" with additional oxide components (e.g., Al2O3, MgO, and / or ZnO). It should be understood that references herein to a β-quartz crystalline phase are intended to describe the β-quartz solid solution crystalline phase.

[0067] In an embodiment, the grain size of the main crystalline phase is less than or equal to 100nm (e.g., less than or equal to 95nm, less than or equal to 90nm, less than or equal to 85nm, less than or equal to 80nm, less than or equal to 75nm, less than or equal to 70nm, less than or equal to 65nm, less than or equal to 60nm, less than or equal to 55nm, or less). In an embodiment, the grain size of the main crystalline phase is greater than or equal to 50nm (e.g., greater than or equal to 55nm, greater than or equal to 60nm, greater than or equal to 65nm, greater than or equal to 70nm, greater than or equal to 75nm, greater than or equal to 80nm, greater than or equal to 85nm, greater than or equal to 90nm, greater than or equal to 95nm, or more). In an embodiment, the grain size of the primary crystalline phase is greater than or equal to 50 nm and less than or equal to 100 nm (e.g., greater than or equal to 55 nm and less than or equal to 95 nm, greater than or equal to 60 nm and less than or equal to 90 nm, greater than or equal to 65 nm and less than or equal to 85 nm, greater than or equal to 70 nm and less than or equal to 80 nm, greater than or equal to 70 nm and less than or equal to 75 nm, and any and all ranges derived from any of the foregoing endpoints). As used herein, grain size is determined by powder X-ray diffraction (XRD) analysis using a scan from 10 to 80 degrees 2θ, unless otherwise specified. Grain size is estimated by measuring the full-width half-maximum intensity (FWHM) and then calculating using the Scherrer equation function available in MDI Jade, a software package for phase identification and quantitative analysis. As used herein, grain size refers to the average grain size.

[0068] In an embodiment, the secondary crystalline phase comprises tetragonal zirconia, which can be expressed as t-ZrO . The formation of tetragonal ZrO in the glass-ceramic requires the presence of ZrO in the precursor glass. Without wishing to be bound by any particular theory, it is believed that the tetragonal ZrO crystalline phase crystallizes before the β-quartz crystalline phase during ceramizing and serves as a nucleation site for the β-quartz crystalline phase. In some embodiments, the composition of the precursor glass and the ceramizing conditions may result in a glass-ceramic comprising additional crystalline phases in addition to those described above.

[0069] In an embodiment, the total crystallinity of the glass-ceramic is high enough to provide enhanced mechanical properties (e.g., hardness, Young's modulus, and scratch resistance), but low enough so that the ion exchangeability and transparency of the glass-ceramic will not deteriorate. As used herein, total crystallinity is provided in wt %, and refers to the sum of the wt % of all crystalline phases present in the glass-ceramic. In an embodiment, the total crystallinity is greater than or equal to 50 wt % (e.g., greater than or equal to 55 wt %, greater than or equal to 60 wt %, greater than or equal to 65 wt %, greater than or equal to 70 wt %, greater than or equal to 75 wt %, greater than or equal to 80 wt %, greater than or equal to 85 wt % or greater). In an embodiment, the total crystallinity is less than or equal to 90 wt % (e.g., less than or equal to 85 wt %, less than or equal to 80 wt %, less than or equal to 75 wt %, less than or equal to 70 wt %, less than or equal to 65 wt %, less than or equal to 60 wt %, less than or equal to 55 wt % or less). In an embodiment, the total crystallinity is greater than or equal to 50 wt % and less than or equal to 90 wt % (e.g., greater than or equal to 55 wt % and less than or equal to 85 wt %, greater than or equal to 60 wt % and less than or equal to 80 wt %, greater than or equal to 65 wt % and less than or equal to 75 wt %, greater than or equal to 50 wt % and less than or equal to 70 wt %, and any and all ranges derived from any of the foregoing endpoints). The total crystallinity of the glass-ceramic is determined by Rietveld quantitative analysis of the XRD data collected as described above. The Rietveld analysis employs a least squares approach to model the XRD data and then determine the concentration of the phase in the sample based on the known lattice and scale factors of the identified phase.

[0070] The glass-ceramics disclosed herein are transparent. As used herein, when the glass-ceramics presents a transmittance of at least 80% over the entire visible wavelength range (400nm to 750nm), it is considered to be transparent. As used herein, transmittance refers to total transmittance and is measured using a Perkin Elmer Lambda 950UV / VIS / NIR spectrophotometer utilizing a 150mm integrating sphere. The sample is mounted at the entrance of the sphere to allow collection of wide-angle scattered light. Total transmittance data are collected using a reference Spectralon reflective dish above the sphere outlet. The percentage (% T) of total transmittance is calculated relative to an open beam baseline measurement. Unless otherwise noted, transmittance is measured on a glass-ceramic article with a thickness of 0.8mm. In an embodiment, the glass-ceramic exhibits a transmittance greater than or equal to 80% (e.g., greater than or equal to 81%, greater than or equal to 82%, greater than or equal to 83%, greater than or equal to 84%, greater than or equal to 85%, greater than or equal to 86%, greater than or equal to 87%, greater than or equal to 88%, greater than or equal to 89%, greater than or equal to 90%, or greater) in the visible light wavelength range.

[0071] The composition of the glass-ceramics will now be described. The composition of the glass-ceramics according to the embodiments is discussed separately below with reference to the composition of the precursor glass. Prior to any ion exchange treatment, the composition of the precursor glass is understood to be the same as the overall composition of the glass-ceramic formed therefrom. The precursor glass compositions described herein allow for the formation of glass-ceramic articles comprising an amorphous phase of lithium aluminosilicate, allowing the amorphous phase to be ion exchanged with a bath containing sodium and / or potassium. The glass-ceramics described herein are formed from a lithium aluminosilicate precursor glass. It should be understood that any of the various described ranges for one component may be combined individually with any of the various described ranges for any other component.

[0072] In the embodiments of the glass-ceramics disclosed herein, SiO2 is the most abundant component. SiO2 serves as the primary glass-forming oxide in the precursor glass and stabilizes the network structure of the precursor glass and the glass-ceramic. Pure SiO2 has a high melting point. Therefore, if the concentration of SiO2 in the glass-ceramic is too high, the formability of the precursor glass composition used to form the glass-ceramic may be reduced because a higher concentration of SiO2 increases the difficulty of melting the glass, which in turn adversely affects the formability of the precursor glass. In embodiments, the glass composition includes SiO2 in an amount generally greater than or equal to 65 mol% (e.g., greater than or equal to 66 mol%, greater than or equal to 67 mol%, greater than or equal to 68 mol%, greater than or equal to 69 mol%, greater than or equal to 70 mol%, greater than or equal to 71 mol%, greater than or equal to 72 mol%, greater than or equal to 73 mol%, greater than or equal to 74 mol%, greater than or equal to 75 mol%, greater than or equal to 76 mol%, greater than or equal to 77 mol%, greater than or equal to 78 mol%, greater than or equal to 79 mol%, or greater). In embodiments, the glass composition includes SiO in an amount less than or equal to 80 mol% (e.g., less than or equal to 79 mol%, less than or equal to 78 mol%, less than or equal to 77 mol%, less than or equal to 76 mol%, less than or equal to 75 mol%, less than or equal to 74 mol%, less than or equal to 73 mol%, less than or equal to 72 mol%, less than or equal to 71 mol%, less than or equal to 70 mol%, less than or equal to 69 mol%, less than or equal to 68 mol%, less than or equal to 67 mol%, less than or equal to 66 mol%, or less). In embodiments, the glass composition includes SiO in an amount greater than or equal to 65 mol% and less than or equal to 80 mol% (e.g., greater than or equal to 66 mol% and less than or equal to 79 mol%, greater than or equal to 67 mol% and less than or equal to 78 mol%, greater than or equal to 68 mol% and less than or equal to 77 mol%, greater than or equal to 69 mol% and less than or equal to 76 mol%, greater than or equal to 70 mol% and less than or equal to 75 mol%, greater than or equal to 71 mol% and less than or equal to 74 mol%, greater than or equal to 72 mol% and less than or equal to 73 mol%, and any and all subranges derived from any of the foregoing endpoints).

[0073] Glass-ceramics include Al2O3. When the amount of Al2O3 is too high, Al2O3 may increase the viscosity of the precursor glass composition and reduce the formability of the glass composition. However, when the concentration of Al2O3 is balanced with the concentration of SiO2 and the concentration of alkali metal oxides in the glass composition, Al2O3 can lower the liquidus temperature of the glass melt, thereby enhancing the liquidus viscosity and improving the compatibility of the precursor glass composition with certain forming processes. Including Al2O3 also improves the mechanical properties and chemical durability of the glass-ceramics. When the precursor glass is ceramized to form the glass-ceramics, the Al2O3 in the precursor glass also supplies the aluminum required to form the beta-quartz solid solution crystalline phase. In embodiments, the precursor glass composition includes Al2O3 in an amount greater than or equal to 8 mol% (e.g., 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%, greater than or equal to 17 mol%, greater than or equal to 18 mol%, greater than or equal to 19 mol%, or greater). In embodiments, the glass composition includes Al2O3 in an amount less than or equal to 20 mol% (e.g., less than or equal to 19 mol%, 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). In embodiments, the glass composition includes Al2O3 in an amount greater than or equal to 8 mol% and less than or equal to 20 mol% (e.g., greater than or equal to 9 mol% and less than or equal to 19 mol%, greater than or equal to 10 mol% and less than or equal to 18 mol%, greater than or equal to 11 mol% and less than or equal to 17 mol%, greater than or equal to 12 mol% and less than or equal to 16 mol%, greater than or equal to 13 mol% and less than or equal to 15 mol%, greater than or equal to 8 mol% and less than or equal to 14 mol%, and any and all subranges derived from any of the foregoing endpoints).

[0074] Glass-ceramic includes one or more alkali metal oxides.Alkali metal oxides promote the chemical strengthening (for example, by ion exchange treatment) of glass-ceramic. The sum of alkali metal oxides (Li2O, Na2O, K2O, Cs2O and Rb2O) in glass-ceramic can be referred to as "R2O", and R2O can be represented by mole %. In some embodiments, glass-ceramic can include a mixture (for example, Li2O and Na2O combination, Li2O and K2O combination, or Li2O, Na2O and K2O combination) of alkali metal oxides. Without wishing to be bound by any particular theory, it is believed that at least some of the alkali metal oxides separate into the residual glass phase of glass-ceramic after ceramizing, and promote the ion exchange of glass-ceramic.

[0075] Glass ceramics include lithium. Including Li2O in the glass ceramics allows ion exchange treatment and reduces the softening point of the precursor glass composition. When the precursor glass is ceramicized, Li2O can be distributed in the residual glass phase of β-quartz solid solution and glass ceramics. In an embodiment, most of the lithium is contained in the residual glass phase of the glass ceramics. In an embodiment, the amount of Li2O included in the precursor glass composition is greater than or equal to 2 mol% (e.g., greater than or equal to 3 mol%, greater than or equal to 4 mol%, greater than or equal to 5 mol%, greater than or equal to 6 mol%, greater than or equal to 7 mol%, or greater). In an embodiment, the amount of Li2O included in the glass composition is less than or equal to 8 mol% (e.g., less than or equal to 7 mol%, less than or equal to 6 mol%, less than or equal to 5 mol%, less than or equal to 4 mol%, less than or equal to 3 mol%, or less). In embodiments, the glass composition includes LiO in an amount greater than or equal to 2 mol% and less than or equal to 8 mol% (e.g., greater than or equal to 3 mol% and less than or equal to 7 mol%, greater than or equal to 4 mol% and less than or equal to 6 mol%, greater than or equal to 4 mol% and less than or equal to 5 mol%, and any and all subranges derived from any of the foregoing endpoints).

[0076] In some embodiments, the amount of Na2O included in the precursor glass composition is less than or equal to 5 mol% (e.g., less than or equal to 4 mol%, less than or equal to 3 mol%, less than or equal to 2 mol%, less than or equal to 1 mol% or less). In some embodiments, the amount of Na2O included in the precursor glass composition is less than or equal to 5 mol% (e.g., less than or equal to 4 mol%, less than or equal to 3 mol%, less than or equal to 2 mol%, less than or equal to 1 mol% or less). In some embodiments, the amount of Na2O included in the precursor glass composition is greater than or equal to 0 mol% and less than or equal to 5 mol% (e.g., greater than or equal to 1 mol% and less than or equal to 4 mol%, greater than or equal to 2 mol% and less than or equal to 3 mol%, and any and all sub-ranges formed by any one of the aforementioned endpoints). In an embodiment, the precursor glass composition is substantially free of Na2O or free of Na2O.

[0077] Glass ceramics and precursor glasses may further include K2O. Including K2O can reduce the melting temperature of the precursor glass and reduce the ceramicization time required for producing glass ceramics. In an embodiment, the amount of K2O included in the precursor glass composition is greater than or equal to 0 mol% (e.g., greater than or equal to 1 mol%, greater than or equal to 2 mol%, greater than or equal to 3 mol%, greater than or equal to 4 mol%, or greater). In some embodiments, the amount of K2O included in the precursor glass composition is less than or equal to 5 mol% (e.g., less than or equal to 4 mol%, less than or equal to 3 mol%, less than or equal to 2 mol%, less than or equal to 1 mol%, or less). In an embodiment, the amount of K2O included in the precursor glass composition is greater than or equal to 0 mol% and less than or equal to 5 mol% (e.g., greater than or equal to 1 mol% and less than or equal to 4 mol%, greater than or equal to 2 mol% and less than or equal to 3 mol%, and any and all sub-ranges formed by any of the aforementioned endpoints). In an embodiment, the precursor glass composition is substantially free of K2O or free of K2O.

[0078] Glass ceramics include MgO. When precursor glass is ceramicized to form glass ceramics, the MgO supply in the precursor glass forms the magnesium required for beta-quartz solid solution crystalline phase, and also improves the melting behavior of glass. In an embodiment, the amount of MgO in the precursor glass is greater than or equal to 4 mol % (for example, greater than or equal to 5 mol %, greater than or equal to 6 mol %, greater than or equal to 7 mol %, 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 %, greater than or equal to 17 mol %, or larger). In an embodiment, the amount of MgO in the precursor glass is less than or equal to 18 mol% (e.g., 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%, less than or equal to 8 mol%, less than or equal to 7 mol%, less than or equal to 6 mol%, less than or equal to 5 mol%, or less). In an embodiment, the amount of MgO in the precursor glass is greater than or equal to 4 mol% and less than or equal to 18 mol% (e.g., greater than or equal to 5 mol% and less than or equal to 17 mol%, greater than or equal to 6 mol% and less than or equal to 16 mol%, greater than or equal to 7 mol% and less than or equal to 15 mol%, greater than or equal to 8 mol% and less than or equal to 14 mol%, greater than or equal to 9 mol% and less than or equal to 13 mol%, greater than or equal to 10 mol% and less than or equal to 12 mol%, greater than or equal to 11 mol% and less than or equal to 18 mol%, and any and all subranges formed by any of the foregoing endpoints).

[0079] The glass ceramics of the embodiment may further include ZnO. When the precursor glass is ceramicized to form glass ceramics, the ZnO in the precursor glass can help form a β-quartz solid solution crystalline phase. In an embodiment, the amount of ZnO included in the glass composition is greater than or equal to 0 mol % (e.g., greater than or equal to 1 mol %, greater than or equal to 2 mol %, greater than or equal to 3 mol %, or greater). In an embodiment, the amount of ZnO included in the glass composition is less than or equal to 4 mol % (e.g., less than or equal to 3 mol %, less than or equal to 2 mol %, less than or equal to 1 mol %, or less). In embodiments, the glass composition includes ZnO in an amount greater than or equal to 0 mol% and less than or equal to 4 mol% (e.g., greater than or equal to 0.5 mol% and less than or equal to 3.5 mol%, greater than or equal to 1 mol% and less than or equal to 3 mol%, greater than or equal to 1.5 mol% and less than or equal to 2.5 mol%, greater than or equal to 0.5 mol% and less than or equal to 2 mol%, and any and all subranges derived from any of the foregoing endpoints). In embodiments, the precursor glass composition is substantially free of ZnO, or free of ZnO.

[0080] Glass ceramics include ZrO2. ZrO2 acts as a nucleating agent, allowing the glass ceramic to be nucleated as a whole. If the concentration of ZrO2 is too low, the precursor glass may not be able to crystallize to form glass ceramics during ceramicization. If the concentration of ZrO2 is too high, when the precursor glass is cooled during the formation process, the precursor glass may spontaneously lose clarity. In addition to serving as a nucleating agent, the presence of ZrO2 in the precursor glass promotes the crystallization of tetragonal ZrO2 during the ceramic process. In an embodiment, the amount of ZrO2 in the precursor glass is greater than 1 mol% (e.g., greater than 1.5 mol%, greater than 2 mol%, greater than 2.5 mol%, greater than 3 mol%, greater than 3.5 mol%, or greater). In an embodiment, the amount of ZrO2 in the precursor glass is greater than 1 mol% and less than or equal to 4 mol% (e.g., greater than or equal to 1.5 mol% and less than or equal to 3.5 mol%, greater than or equal to 2 mol% and less than or equal to 3 mol%, greater than or equal to 2.5 mol% and less than or equal to 4 mol%, and any and all subranges formed by any of the foregoing endpoints).

[0081] In an embodiment, the glass-ceramic may include TiO2. TiO2 can serve as an additional nucleating agent. If the content of TiO2 is too high, the glass-ceramic may have an undesirable colored appearance. For example, even when transparent in the visible light range, the glass-ceramic including TiO2 may have a yellow or brown appearance. In an embodiment, the amount of TiO2 in the precursor glass is greater than or equal to 0 mol% (e.g., greater than or equal to 0.25 mol%, greater than or equal to 0.5 mol%, greater than or equal to 0.75 mol%, or greater). In an embodiment, the amount of TiO2 in the precursor glass is less than or equal to 1 mol% (e.g., less than or equal to 0.75 mol%, less than or equal to 0.5 mol%, less than or equal to 0.25 mol%, or less). In an embodiment, the amount of TiO2 in the precursor glass is greater than or equal to 0 mol% and less than or equal to 1 mol% (e.g., greater than or equal to 0.25 mol% and less than or equal to 0.75 mol%, or greater than or equal to 0 mol% and less than or equal to 0.5 mol%, and any and all subranges formed by the foregoing endpoints). In an embodiment, the glass-ceramic is substantially free of TiO2, or free of TiO2.

[0082] In an embodiment, the glass ceramic may further include BaO. Including BaO in the glass ceramic may increase the refractive index of the residual glass phase in the glass ceramic. In an embodiment, the glass ceramic is substantially free of BaO, or free of BaO.

[0083] In embodiments, the glass-ceramic may optionally include one or more fining agents. In some embodiments, the fining agent may include, for example, tin oxide (SnO2) and / or arsenic oxide. In embodiments, the amount of SnO2 present in the precursor glass composition may be less than or equal to 0.4 mol% (e.g., greater than or equal to 0 mol% and less than or equal to 0.3 mol%, greater than or equal to 0.1 mol% and less than or equal to 0.2 mol%, and all ranges and subranges therebetween). In embodiments, the glass-ceramic is substantially free of SnO2, or free of SnO2. In embodiments, the glass-ceramic may be free of, or substantially free of, one or both of arsenic and antimony.

[0084] In an embodiment, the glass ceramic may be substantially free of Bi2O3, or free of Bi2O3. In an embodiment, the glass ceramic may be substantially free of B2O3, or free of B2O3. In an embodiment, the glass ceramic may be substantially free of Bi2O3 and B2O3, or free of Bi2O3 and B2O3.

[0085] Glass-ceramics are characterized by the molar ratio of the total alkali and divalent metal oxide content to the alumina content. This molar ratio can be expressed as (R2O + R'O) / Al2O3, where R2O is defined above and R'O is the total content of MgO, CaO, SrO, BaO, and ZnO in the glass-ceramic. The glass-ceramics and precursor glass compositions have a (R2O+R'O) / Al2O3 value greater than, or equal to, 0.9 and less than, or equal to, 1.3 (e.g., greater than, or equal to, 0.9 and less than, or equal to, 1.2, greater than, or equal to, 0.9 and less than, or equal to, 1.1, greater than, or equal to, 0.91 and less than, or equal to, 1.09, greater than, or equal to, 0.92 and less than, or equal to, 1.08, greater than, or equal to, 0.93 and less than, or equal to, 1.07, greater than, or equal to, 0.94 and less than, or equal to, 1.06, greater than, or equal to, 0.95 and less than, or equal to, 1.05, greater than, or equal to, 0.96 and less than, or equal to, 1.04, greater than, or equal to, 0.97 and less than, or equal to, 1.03, greater than, or equal to, 0.98 and less than, or equal to, 1.02, greater than, or equal to, 0.99 and less than, or equal to, 1.01, greater than, or equal to, 0.9 and less than, or equal to, 1.0, and any and all subranges derived from any of the foregoing endpoints). When the (R2O+R'O) / Al2O3 value is outside the specified range, the transparency of the glass-ceramic may be undesirably deteriorated.

[0086] In an embodiment, a precursor glass article (also referred to herein as a glass substrate) may be subjected to a ceramizing process to form a glass-ceramic article. In an embodiment, the composition of the precursor glass article includes: greater than or equal to 65 mol% and less than or equal to 80 mol% SiO2; greater than or equal to 8 mol% and less than or equal to 20 mol% Al2O3; greater than or equal to 2 mol% and less than or equal to 8 mol% Li2O; greater than or equal to 4 mol% and less than or equal to 18 mol% MgO; greater than or equal to 0 mol% and less than or equal to 4 mol% ZnO; greater than or equal to 1 mol% and less than or equal to 4 mol% ZrO2; greater than or equal to 0 mol% and less than or equal to 0.4 mol% SnO2; greater than or equal to 0 mol% and less than or equal to 1 mol% TiO2, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.3, and the precursor glass article is substantially free of Bi2O3 and B2O3.

[0087] As can be seen from the above, glass-ceramics according to embodiments can be formed from precursor glass products formed by any suitable method (e.g., slot forming, float forming, roll forming, fusion forming, press forming, etc.). The precursor glass products can be characterized by the manner in which they are formed. For example, the precursor glass products can be characterized as float formable (i.e., formed by a float process), down-drawable, and more specifically, fusion formable or slot-drawable (i.e., formed by a down-draw process (e.g., a fusion draw process or a slot draw process)).

[0088] Glass-ceramics can be formed by ceramizing a precursor glass substrate under any suitable conditions. Ceramics include a nucleation process for forming crystal nuclei in the precursor glass substrate and a ceramizing process for forming the glass-ceramic article. The ceramizing process may also include an intermediate heat treatment performed between the nucleation process and the ceramizing process.

[0089] The nucleation treatment may be performed at any temperature sufficient to form a nucleated glass substrate. In embodiments, the nucleation treatment is performed at a temperature greater than or equal to 700° C. (e.g., greater than or equal to 710° C., greater than or equal to 720° C., greater than or equal to 730° C., greater than or equal to 740° C., greater than or equal to 750° C., greater than or equal to 760° C., greater than or equal to 770° C., greater than or equal to 780° C., greater than or equal to 790° C., or higher). In embodiments, the nucleation treatment is performed at a temperature less than or equal to 800° C. (e.g., less than or equal to 790° C., less than or equal to 780° C., less than or equal to 770° C., less than or equal to 760° C., less than or equal to 750° C., less than or equal to 740° C., less than or equal to 730° C., less than or equal to 720° C., less than or equal to 710° C., or lower). In an embodiment, the temperature at which the nucleation treatment is performed is greater than or equal to 700° C. and less than or equal to 800° C. (e.g., greater than or equal to 710° C. and less than or equal to 790° C., greater than or equal to about 720° C. and less than or equal to about 780° C., greater than or equal to about 730° C. and less than or equal to about 770° C., greater than or equal to about 740° C. and less than or equal to about 760° C., greater than or equal to about 750° C. and less than or equal to about 800° C., and any and all subranges derived from any of the foregoing endpoints). It should be understood that when the nucleation treatment is described as being performed at a given temperature, the temperature refers to the environment (e.g., a kiln, furnace, or oven) in which the nucleation treatment is performed.

[0090] In embodiments, the duration of the nucleation treatment is greater than 10 minutes (e.g., greater than or equal to 30 minutes, greater than or equal to 1.0 hour, greater than or equal to 1.5 hours, greater than or equal to 2.0 hours, greater than or equal to 2.5 hours, greater than or equal to 3.0 hours, greater than or equal to 3.5 hours, or longer). In embodiments, the duration of the nucleation treatment is greater than or equal to 10 minutes and less than or equal to 12 hours (e.g., greater than or equal to 10 minutes and less than or equal to 4 hours, greater than or equal to 30 minutes and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to about 3.0 hours, greater than or equal to 1.5 hours and less than or equal to about 2.5 hours, greater than or equal to 2.0 hours and less than or equal to about 4.0 hours, and any and all subranges derived from any of the foregoing endpoints).

[0091] In an embodiment, the temperature at which the ceramic treatment is performed is greater than or equal to 900° C. (e.g., greater than or equal to 910° C., greater than or equal to 920° C., greater than or equal to 930° C., greater than or equal to 940° C., greater than or equal to 950° C., greater than or equal to 960° C., greater than or equal to 970° C., greater than or equal to 980° C., greater than or equal to 990° C., or higher). In an embodiment, the temperature at which the ceramic treatment is performed is greater than or equal to 900° C. and less than or equal to 1000° C. (e.g., greater than or equal to 910° C. and less than or equal to 990° C., greater than or equal to 920° C. and less than or equal to 980° C., greater than or equal to 930° C. and less than or equal to 970° C., greater than or equal to 940° C. and less than or equal to 960° C., greater than or equal to 950° C. and less than or equal to 1000° C., and any and all subranges formed by any of the foregoing endpoints). It should be understood that when a ceramizing process is described as being performed at a given temperature, the temperature refers to the environment (eg, kiln, furnace, or oven) in which the ceramizing process is performed.

[0092] In embodiments, the time that ceramicization processes continues is greater than 10 minutes (for example, greater than or equal to 30 minutes, greater than or equal to 1.0 hour, greater than or equal to 1.5 hours, greater than or equal to 2.0 hours, greater than or equal to 2.5 hours, greater than or equal to 3.0 hours, greater than or equal to 3.5 hours, or longer). In embodiments, the time that ceramicization processes continues is greater than or equal to 10 minutes and less than or equal to 4.0 hours (for example, greater than or equal to 30 minutes and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to about 3.0 hours, greater than or equal to 1.5 hours and less than or equal to about 2.5 hours, greater than or equal to 2.0 hours and less than or equal to about 4.0 hours, and any and all subranges formed by any one in aforementioned endpoints).

[0093] The ceramizing of the precursor glass substrate for forming the glass-ceramic article can include intermediate thermal treatment.Intermediate thermal treatment is carried out between nucleation treatment and ceramizing treatment, and makes the nucleated glass substrate stand intermediate thermal treatment.Intermediate thermal treatment can be carried out at a temperature between the temperature of nucleation treatment and ceramizing treatment.Intermediate thermal treatment can be considered as secondary nucleation treatment, and helps to ensure that the nucleated glass substrate is fully nucleated, to produce glass-ceramics with desired transparency. In an embodiment, ceramizing does not include intermediate thermal treatment. When ceramizing does not include intermediate thermal treatment, ceramizing treatment can be carried out at any temperature for intermediate thermal treatment and ceramizing treatment as described herein.

[0094] In an embodiment, the temperature at which the intermediate treatment is performed is greater than or equal to 800° C. (e.g., greater than or equal to 810° C., greater than or equal to 820° C., greater than or equal to 830° C., greater than or equal to 840° C., greater than or equal to 850° C., greater than or equal to 860° C., greater than or equal to 870° C., greater than or equal to 880° C., greater than or equal to 890° C., or higher). In an embodiment, the temperature at which the intermediate treatment is performed is greater than or equal to 800° C. and less than or equal to 900° C. (e.g., greater than or equal to 810° C. and less than or equal to 890° C., greater than or equal to 820° C. and less than or equal to 880° C., greater than or equal to 830° C. and less than or equal to 870° C., greater than or equal to 840° C. and less than or equal to 860° C., greater than or equal to 850° C. and less than or equal to 900° C., and any and all subranges formed by any of the foregoing endpoints). It should be understood that when an intermediate heat treatment is described as being performed at a given temperature, the temperature refers to the environment (e.g., kiln, furnace, or oven) in which the intermediate heat treatment is performed.

[0095] In an embodiment, the intermediate heat treatment lasts for greater than 10 minutes (e.g., greater than or equal to 30 minutes, greater than or equal to 1.0 hour, greater than or equal to 1.5 hours, greater than or equal to 2.0 hours, greater than or equal to 2.5 hours, greater than or equal to 3.0 hours, greater than or equal to 3.5 hours, or longer). In an embodiment, the intermediate heat treatment lasts for greater than or equal to 10 minutes and less than or equal to 4.0 hours (e.g., greater than or equal to 30 minutes and less than or equal to 3.5 hours, greater than or equal to 1.0 hour and less than or equal to about 3.0 hours, greater than or equal to 1.5 hours and less than or equal to about 2.5 hours, greater than or equal to 2.0 hours and less than or equal to about 4.0 hours, and any and all subranges formed by any of the foregoing endpoints).

[0096] In embodiments, the glass-ceramic may also be chemically strengthened, for example, by ion exchange, to produce a glass-ceramic with damage resistance for applications such as, but not limited to, display housings. Chemical strengthening of a glass-ceramic article increases the strength of the glass-ceramic article (e.g., as can be characterized by the ring-to-ring test described herein). Figure 1 , the glass-ceramic has a first region under compressive stress (e.g., Figure 1 and a second region in tensile stress or central tension (CT) extending from the DOC to the center or interior region of the glass-ceramic (e.g., Figure 1 As used herein, DOC refers to the depth at which stress in the glass-ceramic changes from compression to tension. At the DOC, stress crosses from positive (compressive) stress to negative (tensile) stress and therefore exhibits a zero stress value.

[0097] According to the convention commonly used in the art, compressive or compressive stress is expressed as a negative (<0) stress, while tensile or tensile stress is expressed as a positive (>0) stress. However, in this specification, CS is expressed as a positive or absolute value (i.e., as described herein, CS=|CS|). The compressive stress (CS) may have a maximum value at the surface of the glass-ceramic, while CS may vary as a function of the distance d from the surface. Referring again to Figure 1 , first compressive layer 120 extends from first surface 110 to a depth d1, while second compressive layer 122 extends from second surface 112 to a depth d2. Compressive stress (including surface CS) is measured using a surface stress meter (FSM) using a commercially available instrument, such as the FSM-6000 manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurement relies on accurate measurement of the stress-optical coefficient (SOC), which is related to the birefringence of the glass-ceramic. The SOC is then measured according to Procedure C (Glass Disc Method) as described in ASTM Standard C770-16, entitled "Standard Test Method for Measurement of Glass Stress-Optical Coefficient," the contents of which are incorporated herein by reference in their entirety.

[0098] Two compressive stress regions ( Figure 1 The compressive stress of the glass (120, 122) is balanced by the tension stored in the central region (130) of the glass. The maximum central tension (CT) and DOC values ​​are measured using the scattered light polarizer (SCALP) technique known in the art.

[0099] The lithium contained in the amorphous phase of the glass-ceramic enables efficient and relatively low-temperature ion exchange (e.g., using a molten sodium nitrate and / or potassium nitrate salt bath). This differs from other β-quartz solid solution glass-ceramics that chemically strengthen using lithium by exchanging magnesium ions, which require very high bath temperatures (e.g., >700°C) due to the slower migration of magnesium ions.

[0100] In the ion exchange treatment, the glass-ceramic article is contacted with a molten salt bath. In an embodiment, the glass-ceramic article may be immersed in a molten salt bath. In an embodiment, the molten salt bath comprises a molten nitrate. In an embodiment, the molten nitrate may be KNO 3 , NaNO 3 , or a combination thereof. In an embodiment, the molten salt bath may comprise less than or equal to 100 wt % KNO 3 (e.g., less than or equal to 90 wt % KNO 3 , less than or equal to 80 wt % KNO 3 , less than or equal to 70 wt % KNO 3 , less than or equal to 60 wt % KNO 3 , less than or equal to 50 wt % KNO 3 , less than or equal to 40 wt % KNO 3 , less than or equal to 30 wt % molten KNO 3 , less than or equal to 20 wt % molten KNO 3 , less than or equal to 10 wt % molten KNO 3 , or less). In an embodiment, the molten salt bath may include greater than or equal to 10 wt% NaNO3 (e.g., greater than or equal to 20 wt% NaNO3, greater than or equal to 30 wt% NaNO3, greater than or equal to 40 wt% NaNO3, greater than or equal to 50 wt% NaNO3, greater than or equal to 60 wt% NaNO3, greater than or equal to 70 wt% NaNO3, greater than or equal to 80 wt% NaNO3, greater than or equal to 90 wt% NaNO3, or greater). In an embodiment, the molten salt bath may include 100 wt% NaNO3. In an embodiment, the molten salt bath may additionally include silicic acid (e.g., less than or equal to 1 wt% silicic acid).

[0101] By immersing the glass ceramic in a molten salt bath, the glass ceramic can be exposed to a molten salt bath. After exposure to the glass ceramic, according to an embodiment, the temperature of the molten salt bath can be greater than or equal to 350°C and less than or equal to 550°C (e.g., greater than or equal to 360°C and less than or equal to 540°C, greater than or equal to 370°C and less than or equal to 530°C, greater than or equal to 380°C and less than or equal to 520°C, greater than or equal to 390°C and less than or equal to 510°C, greater than or equal to 400°C and less than or equal to 500°C, greater than or equal to 410°C and less than or equal to 490°C, greater than or equal to 420°C and less than or equal to 480°C, greater than or equal to 430°C and less than or equal to 470°C, greater than or equal to 440°C and less than or equal to 460°C, greater than or equal to 390°C and less than or equal to 450°C, and any and all subranges formed by any of the aforementioned endpoints). The relatively low molten salt bath range allows for effective ion exchange strengthening of the glass-ceramics described herein, while providing significant cost savings compared to other chemically strengthened β-quartz solid solution glass-ceramics.

[0102] In an embodiment, the glass-ceramic may be exposed to the molten salt bath for a time period greater than or equal to 30 minutes and less than or equal to 48 hours (e.g., greater than or equal to 30 minutes and less than or equal to 24 hours, greater than or equal to 1 hour and less than or equal to 44 hours, greater than or equal to 4 hours and less than or equal to 40 hours, greater than or equal to 8 hours and less than or equal to 36 hours, greater than or equal to 12 hours and less than or equal to 32 hours, greater than or equal to 16 hours and less than or equal to 28 hours, greater than or equal to 20 hours and less than or equal to 24 hours, greater than or equal to 30 minutes and less than or equal to 8 hours, and all subranges formed by any of the foregoing endpoints).

[0103] As mentioned above Figure 1The ion-exchanged glass-ceramic article includes a compressive stress layer extending from its surface to a compression depth. In an embodiment, the compression depth is greater than or equal to 10 μm (e.g., greater than or equal to 15 μm, greater than or equal to 20 μm, greater than or equal to 25 μm, greater than or equal to 30 μm, greater than or equal to 35 μm, greater than or equal to 40 μm, greater than or equal to 45 μm, greater than or equal to 50 μm, greater than or equal to 55 μm, or greater). In an embodiment, the compression depth is greater than or equal to 10 μm and less than or equal to 60 μm (e.g., greater than or equal to 15 μm and less than or equal to 55 μm, greater than or equal to 20 μm and less than or equal to 50 μm, greater than or equal to 25 μm and less than or equal to 45 μm, greater than or equal to 30 μm and less than or equal to 40 μm, greater than or equal to 35 μm and less than or equal to 50 μm, and any and all subranges formed by any of the aforementioned endpoints). In an embodiment, the compression depth is less than or equal to 0.2t, where t is the thickness of the glass-ceramic article, such that the compression depth may be greater than or equal to 10 μm and less than or equal to 0.2t.

[0104] The compressive stress layer of the ion-exchanged glass-ceramic article comprises a maximum compressive stress. In an embodiment, the maximum compressive stress is greater than or equal to 100 MPa or greater. In an embodiment, the maximum compressive stress is greater than or equal to 100 MPa and less than or equal to 1000 MPa.

[0105] After the ion exchange treatment is performed, it is understood that the composition at the surface of the ion-exchanged glass-ceramic is different from the composition of the as-formed glass-ceramic (i.e., the glass-ceramic before the ion exchange treatment). This is because one of the alkali metal ions (e.g., Li + ) is replaced by larger alkali metal ions (e.g., Na + or K + ) is replaced. However, in an embodiment, the composition of the ion-exchanged glass-ceramic product at or near its center still has the composition of the freshly formed glass-ceramic. Similarly, the ion exchange treatment can change the microstructure at the surface of the glass-ceramic (for example, by converting the crystalline region into an amorphous region or vice versa). In an embodiment, the microstructure of the glass-ceramic at or near the depth center of the ion-exchanged glass-ceramic product is identical to the microstructure of the freshly formed glass-ceramic. Therefore, the composition and microstructure at the center of the ion-exchanged glass-ceramic product are expected to be identical to the composition and microstructure of the freshly formed glass-ceramic. For the purpose of this discussion, the center of the ion-exchanged glass-ceramic product refers to any portion of the interior of the ion-exchanged glass-ceramic product that is located at a distance of at least half the thickness from all its surfaces.

[0106] The glass-ceramics disclosed herein (in either as-formed or ion-exchanged form) can be incorporated into another article (e.g., an article having a display (or display article) (e.g., consumer electronics, including mobile phones, tablets, computers, navigation systems, etc.), an architectural article, a transportation article (e.g., a vehicle, train, aircraft, marine craft, etc.), an electrical article, or any article requiring some transparency, scratch resistance, abrasion resistance, or a combination thereof). Figure 2A and Figure 2B The figures illustrate exemplary articles that can be combined with any of the glass-ceramic articles disclosed herein. Specifically, Figure 2A and Figure 2B A consumer electronic device 200 is presented, comprising: a housing 202 having a front surface 204, a rear surface 206, and side surfaces 208; electrical components (not shown) located at least partially or entirely within the housing and including at least a controller, memory, and a display 210 located at or adjacent to the front surface of the housing; and a cover substrate 212 located at or above the front surface of the housing and above the display. In some embodiments, at least a portion of at least one of the cover substrate 212 and / or the housing 202 may comprise any of the glass articles disclosed herein.

[0107] Example

[0108] The following examples will further clarify the embodiments. It should be understood that these examples are not limited to the above embodiments.

[0109] Prepare and ceramicize the precursor glass substrate of the composition listed in the following table 1 according to shown ceramicization program, to form glass ceramic product.When ceramicization program only comprises two steps, do not adopt intermediate heat treatment.In table 1, all components are provided with mole %, and outward appearance is reported according to observation, and phase combination is determined according to X-ray diffraction (XRD) analysis, and KIC fracture toughness is measured according to mountain-shaped notch short bar (CNSB) method.

[0110] Table 1

[0111]

[0112]

[0113] Figure 3 The XRD pattern of Example 1 is shown, indicating the presence of both β-quartz and tetragonal zirconia phases.

[0114] The sample of Example 1 was polished and then etched using 1% hydrofluoric acid for 1 minute. Figure 4 and Figure 5Scanning electron microscope (SEM) images of the polished and etched surfaces at different magnifications show the microstructure of the glass-ceramic.

[0115] As described above, the transmittance of the sample according to Example 1 having a thickness of 0.8 mm was measured. Figure 6 Shows the measured transmittance as a function of wavelength.

[0116] A glass-ceramic sample having the same composition as Example 1 in Table 1 was produced using a ceramizing procedure, wherein a nucleation treatment was performed at 780°C for 2 hours, an intermediate heat treatment was performed at 850°C for 2 hours, and a ceramizing treatment was performed at 930°C for 2 hours. The sample was then ion exchanged in a molten salt bath containing 100 wt% NaNO3 at a bath temperature of 390°C for 3.5 hours to produce a chemically strengthened glass-ceramic sample. The Na2O concentration was measured as a function of the depth below the surface of the chemically strengthened glass-ceramic sample by a microprobe, and the results are shown in FIG. Figure 7 The compression depth is similar to the penetration depth of Na2O. Figure 7 The thickness is about 50 μm.

[0117] The sample produced according to Example 1 in Table 1 had a thickness of 0.8 mm. The sample was then ion exchanged in a molten salt bath containing 100 wt% NaNO3 at a bath temperature of 430°C for 4 hours to produce a chemically strengthened glass-ceramic sample. The non-ion-exchanged sample and the ion-exchanged sample were then subjected to a ring-to-ring test, and the results were as follows: Figure 8 The square data points are samples that have undergone ion exchange, while the circular data points are samples that have not undergone ion exchange. Figure 8 As shown, the ion-exchanged sample exhibits a ring-to-ring intensity that is approximately twice that of the non-ion-exchanged sample.

[0118] The ring-on-ring (ROR) test is a measurement method used to test the surface strength of flat glass-ceramic samples. ASTM C1499-09 (2013), entitled "Standard Test Method for Monotonic Equibiaxial Flexural Strength of Advanced Ceramics at Ambient Temperature," serves as the basis for the ROR test method described herein. The contents of ASTM C1499-09 are incorporated herein by reference in their entirety.

[0119] For ROR testing, a sample is placed between two concentric rings of different sizes to determine the equibiaxial flexural strength (i.e., the maximum stress a material can sustain when subjected to deflection between two concentric rings). In ROR configuration 400, a glass substrate article 410 is supported by a support ring 420 having a diameter D2. A force F is applied to the surface of the glass substrate article by a load cell (not shown) via a load ring 430 having a diameter D1.

[0120] The ratio of the load ring to the support ring diameter, D1 / D2, can range from 0.2 to 0.5. In some embodiments, D1 / D2 is 0.5. The load and support rings 130, 120 should be concentrically aligned to within 0.5% of the support ring diameter, D2. The load cell used for testing should be accurate to within ±1% at any load within the selected range. Testing should be conducted at a temperature of 23 ± 2°C and a relative humidity of 40 ± 10%.

[0121] For fixture design, the radius r of the protruding surface of the load ring 430 is in the range of h / 2≤r≤3h / 2, where h is the thickness of the glass substrate article 410. The load and support rings 430, 420 are made of hardened steel with a hardness HRc>40. ROR fixtures are commercially available.

[0122] The expected failure mechanism for ROR testing is to observe fracture of the glass substrate article 410 originating from the surface 430a within the load ring 430. Failure occurring outside this region (i.e., between the load ring 430 and the support ring 420) is omitted from the data analysis. However, due to the thinness and high strength of the glass substrate article 410, large deflections exceeding ½ of the sample thickness h are sometimes observed. Therefore, it is not uncommon to observe a high percentage of failure originating from beneath the load ring 430. Without knowing the stress development within and beneath the ring (collected via strain gauge analysis) and the cause of failure for each sample, it is impossible to accurately calculate stress. Therefore, ROR testing focuses on measuring the peak load at the failure site during response.

[0123] The strength of glass-based products depends on the presence of surface defects. However, because the strength of glass is inherently statistical, it is impossible to precisely predict the likelihood of a defect of a given size. Therefore, a probability distribution can be used as a statistical representation of the acquired data.

[0124] Unless otherwise indicated, all components, relationships, and ratios described in this specification are provided in mole %. Regardless of whether explicitly stated before or after the disclosed range, all ranges disclosed in this specification include any and all ranges and sub-ranges encompassed by the broadly disclosed range.

[0125] Those skilled in the art will appreciate 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. Therefore, this disclosure is intended to encompass modifications and variations of the various embodiments provided herein that fall within the scope of the appended claims and their equivalents.

Claims

1. A glass ceramic product comprising: a main crystalline phase comprising a β-quartz solid solution; A secondary crystalline phase comprising tetragonal ZrO2; and Lithium aluminum silicate amorphous phase, The molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.3, R2O is Li2O+Na2O+K2O+Cs2O+Rb2O, and R'O is MgO+CaO+SrO+BaO+ZnO.

2. The glass-ceramic article of claim 1, wherein the glass-ceramic article has a crystallinity greater than 50 wt%. 3 . The glass-ceramic product according to claim 1 , wherein the grain size of the main crystalline phase is greater than or equal to 50 nm and less than or equal to 100 nm. 4 . The glass ceramic article according to claim 1 , wherein the glass ceramic article has a transmittance greater than or equal to 90% in a wavelength range of 400 nm to 750 nm at a thickness of 0.8 mm.

5. The glass-ceramic article according to claim 1 or 2, comprising greater than or equal to 65 mol% and less than or equal to 80 mol% of SiO2.

6. The glass-ceramic article according to claim 1 or 2, comprising greater than or equal to 8 mol% and less than or equal to 20 mol% of Al2O3.

7. The glass-ceramic article of claim 1 or 2, comprising greater than or equal to 4 mol% and less than or equal to 18 mol% of MgO.

8. The glass-ceramic article according to claim 1 or 2, comprising greater than or equal to 0 mol% and less than or equal to 4 mol% of ZnO.

9. The glass-ceramic article according to claim 1 or 2, comprising greater than or equal to 1 mol% and less than or equal to 4 mol% ZrO2.

10. The glass-ceramic article according to claim 1 or 2, comprising greater than or equal to 0 mol% and less than or equal to 0.4 mol% of SnO2.

11. The glass-ceramic article of claim 1 or 2, comprising greater than or equal to 0 mol% and less than or equal to 1 mol% TiO2.

12. The glass-ceramic article of claim 1 or 2, wherein the glass-ceramic article is substantially free of TiO2.

13. The glass-ceramic article of claim 1 or 2, wherein the glass-ceramic article is substantially free of Bi2O3 and B2O3.

14. The glass-ceramic article of claim 1 or 2, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.

1.

15. The glass-ceramic article of claim 1 or 2, wherein the molar ratio (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.

0.

16. The glass-ceramic article of claim 1 or 2, comprising greater than or equal to 2 mol% and less than or equal to 8 mol% Li2O.

17. The glass-ceramic article according to claim 1 or 2, comprising: greater than or equal to 0 mol % and less than or equal to 5 mol % Na2O; and Greater than or equal to 0 mol % and less than or equal to 5 mol % K2O.

18. The glass-ceramic article of claim 1 or 2, comprising a compressive stress layer extending from the surface to a compression depth.

19. The glass-ceramic article of claim 18, wherein the compression depth is greater than or equal to 10 μm.

20. The glass-ceramic article of claim 18, wherein the compression depth is less than or equal to 60 μm.

21. The glass-ceramic article of claim 18, wherein the compression depth is less than or equal to 0.2t, where t is the thickness of the glass-ceramic article.

22. The glass-ceramic article of claim 18, wherein the compressive stress layer comprises a compressive stress greater than or equal to 100 MPa.

23. A consumer electronic product comprising: a housing comprising a front surface, a rear surface, and side surfaces; an electronic component at least partially located within the housing, the electronic component including a controller, a memory, and a display, the display being located at or adjacent to the front surface of the housing; and a cover substrate disposed above the display, At least a portion of at least one of the housing or the cover substrate comprises the glass-ceramic article according to claim 1 or 2.

24. A method for producing a glass-ceramic product, comprising: nucleating the glass substrate to form a nucleated glass substrate; Ceramics are performed on the nucleated glass substrate to form a glass-ceramic product. wherein the glass substrate comprises lithium aluminosilicate, and the glass-ceramic article comprises: A main crystalline phase comprising a β-quartz solid solution; A secondary crystalline phase comprising tetragonal ZrO2; and Lithium aluminum silicate amorphous phase, The molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.3, R2O is Li2O+Na2O+K2O+Cs2O+Rb2O, and R'O is MgO+CaO+SrO+BaO+ZnO.

25. The method of claim 24, wherein the nucleation step comprises processing in an environment at a temperature greater than or equal to 700°C and less than or equal to 800°C.

26. The method of claim 24 or 25, wherein the nucleation step lasts for a time greater than or equal to 10 minutes and less than or equal to 12 hours.

27. The method of claim 24 or 25, wherein the ceramizing step comprises treatment in an environment at a temperature greater than or equal to 900°C and less than or equal to 1000°C.

28. The method of claim 24 or 25, wherein the ceramizing step lasts for a period of time greater than or equal to 10 minutes and less than or equal to 4 hours.

29. method as claimed in claim 24 or 25, further comprise the intermediate thermal treatment of nucleation glass substrate, wherein intermediate thermal treatment is carried out after this nucleation step and before this ceramizing step, and is included in the processing in the environment under the temperature higher than this nucleation step and lower than this ceramizing step temperature.

30. The method of claim 29, wherein the intermediate heat treatment comprises treatment in an environment at a temperature greater than or equal to 800°C and less than or equal to 900°C.

31. The method of claim 29, wherein the intermediate heat treatment lasts for a period greater than or equal to 10 minutes and less than or equal to 4 hours.

32. The method of claim 24 or 25, further comprising ion exchanging the glass-ceramic article in a molten salt bath, wherein the molten salt bath comprises NaNO3, KNO3, or a combination thereof.

33. The method of claim 32, wherein the temperature of the molten salt bath is greater than or equal to 350°C and less than or equal to 550°C.

34. The method of claim 32, wherein the ion exchange lasts for a period of time greater than or equal to 30 minutes and less than or equal to 24 hours.

35. The method of claim 24 or 25, wherein the glass substrate comprises: 65 mol% or more and 80 mol% or less of SiO2; 8 mol% or more and 20 mol% or less of Al2O3; 2 mol% or more and 8 mol% or less of Li2O; 4 mol% or more and 18 mol% or less of MgO; 0 mol % or more and 4 mol % or less of ZnO; 1 mol % or more and 4 mol % or less of ZrO 2 ; and greater than or equal to 0 mol % and less than or equal to 0.4 mol % of SnO2, The molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.

3.

36. The method of claim 24 or 25, wherein the molar ratio of (R2O+R'O) / Al2O3 is greater than or equal to 0.9 and less than or equal to 1.

1.

37. The method of claim 24 or 25, wherein the glass substrate comprises: greater than or equal to 0 mol % and less than or equal to 1 mol % of TiO2, The glass substrate basically does not contain Bi2O3 and B2O3.

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