Glasses and glass-ceramics with metal oxide concentration gradients

Abstract

To provide a glass based object exhibiting improved damage resistance including improved fracture resistance.SOLUTION: The invention is configured so that, density of metal oxide which varies along a thickness range from almost 0 t to 0.3 t and which is not zero, is applied to a glass based object comprising a first surface and a second surface which is arranged on a side opposite to the first surface which define a thickness (t), and then a stress profile which reduces from the first surface to a value between the first surface and the second surface, and increases from the value to the second surface is applied. The applied stress profile has a CT area which is approximated by a stress (x)=MaxCT-(((MaxCT (n+1)) / 0.5n) |(x / t)-0.5|n), and in the formula, MaxCT is a maximum CT value, and is applied as a positive value of a unit of MPa, and x is a position along a thickness (t) of micrometer, and n is a value between 1.5 and 5.SELECTED DRAWING: Figure 39

Description

Description of Related Applications

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Patent Application No. 62 / 194,967, filed July 21, 2015; U.S. Provisional Patent Application No. 62 / 171,110, filed June 4, 2015; U.S. Provisional Patent Application No. 62 / 117,585, filed February 18, 2015; and U.S. Provisional Patent Application No. 62 / 061,372, filed October 8, 2014, the contents of which are relied upon and incorporated herein by reference in their entireties. [Technical Field]

[0002] The present disclosure relates to glass-based articles that exhibit improved damage resistance, including improved fracture resistance, and more particularly to glass and glass-ceramic articles that exhibit a non-zero metal oxide concentration gradient or a metal oxide concentration that varies along a substantial portion of their thickness. [Background technology]

[0003] Glass-based articles often experience severe impacts that can result in large scratches on the surface of such articles. Such scratches can extend to a depth of up to about 200 micrometers from the surface. Traditionally, thermally strengthened glass has been used to prevent breakage that could result in such scratches in the glass. This is because thermally strengthened glass often exhibits a large compressive stress (CS) layer (e.g., about 21% of the total thickness of the glass), which can prevent scratch propagation and therefore breakage. An example of a stress profile resulting from thermal strengthening is shown in FIG. 1. In FIG. 1, a heat-treated glass-based article 100 has a first surface 101, a thickness t1, and a surface CS 110. The glass-based article 100 exhibits a decreasing CS from the first surface 101 to a depth of layer (DOL) 130, as defined herein, where the stress changes from compressive to tensile, reaching a maximum central tension (CT) 120.

[0004] Thermal strengthening is currently limited to thick glass-based articles (i.e., glass-based articles with a thickness t1 of about 3 millimeters or greater) because a sufficient thermal gradient must be created between the core and surface of such articles to achieve thermal strengthening and the desired residual stresses. Such thick articles are undesirable or impractical in many applications, such as displays (e.g., consumer electronics including cell phones, tablets, computers, navigation systems, etc.), buildings (e.g., windows, shower panels, countertops, etc.), transportation (e.g., automobiles, trains, aircraft, marine vessels, etc.), appliances, or any application requiring a thin, lightweight article that demands good fracture resistance.

[0005] While known chemically strengthened glass-based articles do not exhibit the stress profile of thermally strengthened glass-based articles, chemical strengthening is not limited by the thickness of the glass-based article in the same manner as thermal strengthening. An example of a stress profile resulting from chemical strengthening (e.g., by ion exchange) is shown in FIG. 2. In FIG. 2, a chemically strengthened glass-based article 200 has a first surface 201, a thickness t2, and a surface CS 210. The glass-based article 200 exhibits a CS that decreases from the first surface 201 to a DOC 230, as defined herein, at the depth of this layer, the stress changes from compressive to tensile, reaching a maximum CT 220. As shown in FIG. 2, such a profile exhibits a flat CT region, or a CT region of constant or nearly constant tensile stress, and often a smaller maximum CT value compared to the maximum median value shown in FIG. 1. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need for thin glass-based articles that exhibit improved fracture resistance. [Means for solving the problem]

[0007] A first aspect of the present disclosure relates to a glass-based article having a first surface and a second surface opposite the first surface, the second surface defining a thickness (t) (e.g., about 3 millimeters or less, about 1 millimeter or less, or about 0.5 millimeters or less), and a stress profile extending along the thickness. In one or more embodiments, all points on the stress profile between thickness ranges of about 0·t to 0.3·t and from greater than 0.7·t have a tangent less than about −0.1 MPa / micrometer or greater than about 0.1 MPa / micrometer.

[0008] In embodiments, the glass-based article has a non-zero metal oxide concentration that varies along a substantial portion or the entire thickness of the glass-based article. The variation in metal oxide concentration may be referred to herein as a gradient. In some embodiments, the metal oxide concentration varies non-zero along a thickness range of about 0·t to 0.3·t. In some embodiments, the metal oxide concentration varies non-zero along a thickness range of about 0·t to 0.35·t, about 0·t to 0.4·t, about 0·t to 0.45·t, or about 0·t to 0.48·t. The metal oxide may be described as causing stress in the glass-based article. The variation in metal oxide concentration may include a change of about 0.2 mol % along a thickness segment of about 100 micrometers. The concentration variation may be continuous along the thickness range. In some embodiments, the concentration variation may be continuous along a thickness segment ranging from about 10 micrometers to about 30 micrometers.

[0009] In some embodiments, the concentration of metal oxide decreases from the first surface to a point between the first surface and the second surface, and increases from that point to the second surface.

[0010] As used herein, the metal oxide includes strengthening ions or ions that cause CS in the glass-based article. In some embodiments, the metal oxide has the largest ionic diameter of all metal oxides in the glass-based substrate. In one or more embodiments, the metal oxide may include an alkali metal oxide or a combination of different metal oxides or alkali metal oxides. Exemplary metal oxides include AgO. Exemplary alkali metal oxides include any one or more of LiO, NaO, KO, RbO, and CsO. The metal oxide may be present in a non-zero concentration of the particular metal oxide that varies along a substantial portion or the entire thickness of the glass-based article. In some embodiments, the concentration of the metal oxide decreases from the first surface to a point between the first and second surfaces and then increases from that point to the second surface. The concentration of the metal oxide may be non-zero at that point.

[0011] The concentration of the metal oxide may be about 0.05 mol% or greater or about 1 mol% or greater throughout the thickness. For example, the concentration of Na2O may be about 0.05 mol% or greater throughout the thickness of the glass-based article, but such concentration of Na2O decreases from the first surface to a point between the first and second surfaces and increases from that point to the second surface. In some cases, the total concentration of metal oxide along the entire thickness of the glass-based article is in the range of about 1 mol% to about 20 mol%. In some embodiments, the concentration of metal oxide near the surface may be greater than 1 or 1.5 times (e.g., 5, 10, 15, or even 20 times) the concentration of the same metal oxide at a depth ranging from about 0.4 t to about 0.6 t. The concentration of the metal oxide may be determined from a baseline amount of the metal oxide concentration in the glass-based article before it is altered to exhibit a concentration profile (i.e., a gradient or variation as described herein).

[0012] In one or more embodiments, the glass-based article has a concentration of a first metal oxide and a concentration of a second metal oxide such that the concentration of the first metal oxide ranges from about 0 mol% to about 15 mol% along a first thickness range of about 0t to about 0.5t, and the concentration of the second metal oxide ranges from about 0 mol% to about 10 mol% along a second thickness range of about 0 micrometers to about 25 micrometers. The glass-based article may have a concentration of an optional third metal oxide. The first metal oxide may be NaO and the second metal oxide may be KO.

[0013] In one or more embodiments, the glass-based article has a surface Cs of about 150 MPa or greater, or about 200 MPa or greater. In one or more embodiments, the glass-based article may have a surface Cs of greater than about 300 MPa, greater than about 600 MPa, or greater than about 700 MPa. The glass-based article may exhibit a chemical depth of about 0.4·t or greater.

[0014] In some embodiments, the glass-based article may have a CS layer extending from the first surface to a DOC of about 0.1 t or greater. In some cases, the glass-based article has a CT layer having a non-zero metal oxide concentration that varies along a substantial portion of the thickness t. The CT layer may exhibit a maximum CT such that the ratio of maximum CT to surface CS is in the range of about 0.01 to about 0.5. The maximum CT may be about 25 MPa or greater.

[0015] In one or more embodiments, the glass-based article has a structure in which, when the glass-based article is broken, the glass-based article is broken into 1 square inch (approximately 6.4516 cm 2 In some cases, the glass-based article may exhibit a fracture resistance of at least 2 fragments per square inch (approximately 6.4516 cm). 2 ) may break into 3 or more pieces, 5 or more pieces, or 10 or more pieces.

[0016] In some cases, the glass-based article has a thermal conductivity of about 0 J / m2 Over 20J / m 2 It may exhibit a stored tensile energy of less than 100 kJ / cm.

[0017] The CT region of one or more embodiments of the glass-based article has the formula: Stress(x)=MaxCT-(((MaxCT·(n+1)) / 0.5 n )·|(x / t)-0.5| n ) where MaxCT is the maximum CT value, given as a positive value in units of MPa, x is the position along the thickness (t) in micrometers, and n is between 1.5 and 5 (or 1.8 to about 2).

[0018] The glass-based article may include an amorphous structure, a crystalline structure, or a combination thereof. The glass-based article may be transparent or opaque. In some embodiments, the glass-based article exhibits a substantially white or substantially black color. Additionally or alternatively, the glass-based article may include a colorant to impart a particular color.

[0019] A second aspect of this disclosure relates to an amorphous glass substrate having a composition comprising, in mole percent, SiO in an amount ranging from about 68 to about 75, AlO in an amount ranging from about 12 to about 15, BO in an amount ranging from about 0.5 to about 5, LiO in an amount ranging from about 2 to about 8, NaO in an amount ranging from about 0 to about 6, MgO in an amount ranging from about 1 to about 4, ZnO in an amount ranging from about 0 to about 3, and CaO in an amount ranging from about 0 to about 5. In some embodiments, the glass substrate has a ratio of LiO to RO ranging from about 0.5 to about 1; a difference between the total amount of RO and the amount of AlO ranging from about -5 to about 0; and R in an amount ranging from about 0 to about 3. x the difference between the total amount (mol %) of O and the amount of Al2O3; and the ratio of the amount (mol %) of MgO to the total amount (mol %) of RO ranging from about 0 to about 2.

[0020] In one or more embodiments, the glass substrate is ion-exchangeable. In other embodiments, the glass substrate is strengthened by ion-exchange.

[0021] A third aspect of this disclosure relates to a method of forming a fracture-resistant glass-based article as described herein, the method comprising providing a glass-based substrate having a first surface and a second surface defining a thickness of about 3 millimeters or less, and imparting a stress profile to the glass-based substrate having a CT layer and a CS layer, the CS layer having a surface CS, a chemical depth of about 0.4t or greater and a DOC of about 0.1t or greater, the CT layer having a maximum CT, and a ratio of the maximum CT to the surface CS of about 0.01 to about 0.5.

[0022] Additional features and advantages will be set forth in the following detailed description, and in part will become readily apparent to those skilled in the art from that description, or may be learned by practicing the embodiments as described herein, including the following detailed description, claims, and accompanying drawings.

[0023] It is to be understood that both the foregoing general description and the following detailed description are merely explanatory and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate one or more embodiments, and together with the description, serve to explain the principles and operation of various embodiments. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view through the thickness of a known thermally strengthened glass-based article; [Figure 2] 1 is a cross-sectional view through the thickness of a known chemically strengthened glass-based article; [Figure 3] 1 is a cross-sectional view through the thickness of a chemically strengthened glass-based article according to one or more embodiments of the present disclosure; [Figure 4]Schematic cross-section of a ring-on-ring device [Figure 5] Graph showing the concentration of Na2O in known chemically strengthened glass-based articles and glass-based articles according to one or more embodiments of the present disclosure. [Figure 6] Graph showing CT and DOC values ​​as a function of ion exchange time, according to one or more embodiments of the present disclosure. [Figure 7] Graph comparing stress profiles as a function of depth for known chemically strengthened glass-based articles and glass-based articles according to one or more embodiments of the present disclosure. [Figure 8] Graph of stress profiles for known chemically strengthened glasses and glass-ceramics [Figure 9] Graphs of stress profiles for glasses and glass-ceramics according to one or more embodiments of the present disclosure. [Figure 9A] Graph of breakage height in drop test of Example 3D [Figure 10] Graph comparing known stress profiles of chemically strengthened glass-based articles and stress profiles of glass-based articles according to one or more embodiments of the present disclosure. [Figure 11] Graph showing stress profiles for Examples 4A-4D as a function of thickness [Figure 12] Graph showing individual stored tensile energy data points for Examples 4B-4D [Figure 13] Graph showing the concentration of K2O and Na2O as a function of depth for Examples 4B-4D [Figure 14] Graph showing the same data as in Figure 13, but with a different scale to more clearly show the concentration of Na2O as a function of depth. [Figure 15] Graph showing stress profiles for Examples 4A and 4C-4F as a function of depth [Figure 16] Graph showing different scales in Figure 14 [Figure 17] Graph showing stress profiles for Examples 5A-5G as a function of depth [Figure 18]Graph showing DOC values ​​for Examples 5A-5G as a function of duration of the second and / or third ion exchange steps. [Figure 19] Graph showing the C values ​​of Examples 5A-5G as a function of the duration of the second and / or third ion exchange steps. [Figure 20] Graph showing stress profiles for Examples 6A-1 through 6A-6 as a function of depth. [Figure 21] Graph showing CT and DOC values ​​of Examples 6A-1 to 6A-6 as a function of ion exchange time. [Figure 22] Graph showing stress profiles for Examples 6B-1 through 6B-6 as a function of depth. [Figure 23] Graph showing CT and DOC values ​​of Examples 6B-1 to 6B-6 as a function of ion exchange time. [Figure 24] Graph showing stress profiles for Examples 6C-1 through 6C-6 as a function of depth. [Figure 25] Graph showing CT and DOC values ​​of Examples 6C-1 to 6C-6 as a function of ion exchange time. [Figure 26] Graph showing stress profiles for Examples 6D-1 to 6D-6 as a function of depth [Figure 27] Graph showing CT and DOC values ​​of Examples 6D-1 to 6D-6 as a function of ion exchange time. [Figure 28] Graph showing CT as a function of ion exchange time for Examples 7A-7G [Figure 29] Graphs showing the change in median tension value and stored tensile energy as a function of ion exchange time, both for Examples 7A-7G. [Figure 30] Graph showing stress profiles for Comparative Example 8A and Example 8B as a function of depth [Figure 31] Graph showing stored tensile energy of Comparative Example 8A and Example 8B as a function of CT. [Figure 32] Graph showing stored tensile energy of Comparative Example 8C and Example 8D as a function of CT. [Figure 33] Graph showing drop breakage height for Examples 2, 6, and 9B, and Comparative Example 9A [Figure 34] Graph showing ring-on-ring results during polishing for Examples 2, 6, and 9B, and Comparative Example 9B [Figure 35] Weibull distribution plot showing four-point bending results for Examples 2 and 9B [Figure 36] 1 is a schematic cross-sectional view of an embodiment of an apparatus used to perform the inverted ball on sandpaper (IBoS) test described in this disclosure. [Figure 37] Schematic cross-sectional view showing the dominant mechanism of failure due to damage introduction in bending that typically occurs in glass-based articles used in portable or handheld electronic devices. [Figure 38] 1 is a flow diagram of a method for performing IBoS testing on the device described herein. [Figure 39] Graphs illustrating various stress profiles according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0025] Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying examples and drawings.

[0026] In the following description, like reference characters refer to like or corresponding parts throughout the several views shown in the drawings. It is also understood that, unless otherwise specified, terms such as "upper," "lower," "outer," "inner," and the like are words of convenience and should not be considered limiting terms. Furthermore, whenever a group is described as comprising at least one of a group of elements and combinations thereof, it is understood that the group may comprise, consist essentially of, or consist of any of those listed elements, either individually or in combination with one another. Similarly, whenever a group is described as consisting of at least one of a group of elements or combinations thereof, it is understood that the group may consist of any of those listed elements, either individually or in combination with one another. Unless otherwise specified, ranges of values, when recited, include both the upper and lower limits of the range, as well as any ranges therebetween. As used herein, unless otherwise specified, nouns are intended to refer to "at least one" or "one or more" objects. It is also understood that the various features disclosed in this specification and in the drawings may be used in any and all combinations.

[0027] As used herein, the terms "glass-based article" and "glass-based substrate" are used in the broadest sense to include any object made entirely or partially from glass. Glass-based articles include laminates of glass and non-glass materials, laminates of glass and crystalline materials, and glass-ceramics (containing amorphous and crystalline phases). Unless otherwise specified, all compositions are expressed in mole percent (mol%).

[0028] Please note that the terms "substantially" and "about" may be used herein to represent the inherent degree of uncertainty that may contribute to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to represent the degree to which a quantitative representation may vary from the stated standard without changing the basic functionality of the subject matter at issue. Thus, for example, a glass-based article that is "substantially free of MgO" is one in which MgO is not actively added or batched into the glass-based article, but may be present in negligible amounts as a contaminant.

[0029] Referring generally to the drawings, and particularly to Figures 1-3, it will be understood that the illustrations are for purposes of describing particular embodiments and are not intended to limit the scope of the disclosure or the appended claims thereto. The drawings are not necessarily drawn to scale, and certain features and certain views of the drawings may be shown exaggerated in scale or schematic form for clarity and conciseness.

[0030] As used herein, DOC refers to the depth within a glass-based article where stress changes from compressive to tensile. At the DOC, the stress crosses from positive (compressive) to negative (tensile) stress (e.g., 130 in Figure 1), and therefore exhibits a stress value of zero.

[0031] As used herein, the terms "chemical depth," "chemical depth of layer," and "depth of chemical layer" may be used interchangeably and refer to the depth to which metal oxide or alkali metal oxide ions (e.g., metal ions or alkali metal ions) diffuse into a glass-based article and the depth at which the concentration of the ions reaches a minimum value as determined by electron probe microanalysis (EPMA) or glow discharge optical emission spectroscopy (GD-OES). Specifically, the depth of NaO diffusion or the depth of Na + Ion concentrations may be determined using EPMA and FSM (described in more detail below).

[0032] According to convention commonly used in the art, compression is expressed as a negative (<0) stress and tension as a positive (>0) stress. However, throughout this description, Cs will be expressed as a positive or absolute value - i.e., as set forth herein, Cs = |Cs|.

[0033] Described herein are thin, chemically strengthened glass-based articles, including glasses such as silicate glasses, including alkali-containing glasses, and glass-ceramics, that may be used as cover glass for portable electronic devices and touch-enabled displays. The glass-based articles may also be used in displays (or display articles) (e.g., billboards, point-of-sale systems, computers, navigation systems, etc.), architectural articles (walls, fixtures, panels, windows, etc.), transportation articles (e.g., automotive applications, trains, aircraft, marine vessels, etc.), electrical appliances (e.g., washing machines, dryers, dishwashers, refrigerators, etc.), or any article requiring some degree of fracture resistance.

[0034] In particular, the glass-based articles described herein are thin and typically exhibit stress profiles achievable only by thermally strengthening thicker glass articles (e.g., greater than about 2 mm or 3 mm in thickness). The glass-based articles exhibit unique stress profiles along their thickness. In some cases, the glass-based articles exhibit greater surface CS than thermally strengthened glass articles. In one or more embodiments, the glass-based articles exhibit a deep compression layer (CS increasing or decreasing more gradually than known chemically strengthened glass-based articles) such that the glass-based articles exhibit significantly improved fracture resistance even when the glass-based article or a device containing it is dropped onto a hard, rough surface. The glass-based articles of one or more embodiments exhibit greater maximum CT values ​​than some known chemically strengthened glass substrates.

[0035] The CS and depth of compressive stress layer ("DOL") are measured using means known in the art. DOL is distinguished from DOC by a measurement technique in which the DOL is determined by a surface stress meter (FSM) using commercially available instruments, such as the FSM-6000 manufactured by Luceo Co., Ltd. (Tokyo, Japan). Methods for measuring CS and depth of layer are described in ASTM 1422C-99, entitled "Standard Specification for Chemically Strengthened Flat Glass," and ASTM 1279.19779, entitled "Standard Test Method for Non-Destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-Strengthened, and Fully-Tempered Flat Glass," the contents of which are incorporated herein by reference in their entirety. Surface stress measurement relies on accurate measurement of the stress optical coefficient (SOC), which is related to the birefringence of the glass. SOC is then measured by methods known in the art, such as the fiber and four-point bend method, and the bulk cylinder method, both of which are described in ASTM Standard C770-98(2008), entitled "Standard Test Method for Measurement of Glass Stress-Optical Coefficient," the contents of which are incorporated herein by reference in their entirety.

[0036] For tempered glass-based articles in which the CS layer extends to greater depths within the glass-based article, the FSM technique may suffer from contrast issues that affect the observed DOL values. At deeper DOL values, the contrast between the TE and TM spectra becomes inadequate, and therefore calculating the difference between the TE and TM spectra—determining the DOL—may become more difficult. Furthermore, the FSM technique cannot determine the stress profile (i.e., the variation of CS as a function of depth within the glass-based article). Furthermore, the FSM technique cannot determine the DOL resulting from the ion exchange of certain elements, such as, for example, sodium with lithium.

[0037] To more accurately determine the DOC and stress profile for strengthened glass-based articles, the techniques described below were developed.

[0038] In U.S. Patent Application No. 13 / 463,322 of the same title, filed May 3, 2012 by Rostislav V. Roussev et al. (hereinafter "Roussev I"), which claims priority to U.S. Provisional Patent Application No. 61 / 489,800, filed May 25, 2011, entitled "Systems And Methods for Measuring the Stress Profile of Ion-Exchanged Glass," two methods are disclosed for obtaining detailed and accurate stress profiles (stress as a function of depth) of tempered or chemically strengthened glass. Spectra of coupled optical modes for TM and TE polarizations are collected by a prism coupling technique and used in combination to obtain detailed and accurate TM and TE refractive index profiles. TM (z) and n TE (z). The contents of the prior application are hereby incorporated by reference in their entirety.

[0039] In one embodiment, the detailed refractive index profile is obtained from the mode spectrum using the inverse Wenzel-Kramers-Brillouin (IWKB) method.

[0040] In another embodiment, the detailed refractive index profile is obtained by fitting the measured mode spectrum to a numerically calculated spectrum of a predetermined functional form that describes the shape of the refractive index profile, and obtaining the parameters of the functional form from the best fit. The detailed stress profile S(z) is calculated from the difference between the obtained TM and TE refractive index profiles by using known values ​​of the stress optical coefficient (SOC): S(z)=[n TM (z)-n TE (z)] / SOC (2) Due to the small value of SOC, the birefringence n TM (z)-n TE (z) is the refractive index n TM (z) and n TE (z) is a small fraction (typically on the order of 1%) of the modal effective refractive index. To obtain a stress profile that is not significantly distorted by noise in the measured modal spectrum, it is necessary to determine the modal effective refractive index with an accuracy on the order of 0.00001 RIU. The method disclosed in Roussev I further includes techniques applied to the raw data to ensure such high accuracy of the measured modal refractive index despite noise and / or insufficient contrast in the collected TE and TM mode spectra or images of the mode spectra. Such techniques include noise averaging, filtering, and curve fitting to find the locations of extrema corresponding to the modes with sub-pixel resolution.

[0041] Similarly, U.S. Patent Application No. 14 / 033,954, filed September 23, 2013, by Rostislav V. Roussev et al., which claims priority to U.S. Provisional Patent Application No. 61 / 706,891, filed September 28, 2012, entitled "Systems and Methods for Measuring Birefringence in Glass and Glass-Ceramics" (hereinafter "Roussev II"), discloses apparatus and methods for optically measuring birefringence on the surfaces of glasses and glass-ceramics, including opaque glasses and glass-ceramics. Unlike Roussev I, in which separate modal spectra are identified, the method disclosed in Roussev II relies on a thorough analysis of the angular intensity distributions for TM and TE light reflected at the prism-sample interface in a prism-coupled measurement format. The contents of the prior application are incorporated herein by reference in their entirety.

[0042] Therefore, the accurate distribution of reflected light intensity versus angle is much more important than in conventional prism-coupled stress measurements, which only determine the positions of distinct modes. To this end, the methods disclosed in Roussev I and Roussev II include techniques for normalizing the intensity spectrum, including normalizing to a reference image or signal, correcting for detector nonlinearities, averaging multiple images to reduce image noise and speckle, and applying digital filtering to further smooth the intensity angular spectrum. Furthermore, one method involves forming a contrast signal, which is additionally normalized to correct for fundamental differences in shape between the TM and TE signals. The above-described method relies on obtaining two nearly identical signals and determining their relative displacement with subpixel resolution by comparing the portions of the signals containing the steepest slopes. Birefringence is proportional to the relative displacement, and the coefficient is determined by the design of the device, including the shape and refractive index of the prism, the focal length of the lens, and the pixel spacing on the sensor. The stress is determined by multiplying the measured birefringence by a known stress-optical coefficient.

[0043] In another disclosed method, the derivatives of the TM and TE signals are determined after applying some combination of the signal processing techniques described above. The positions of the maximum derivatives of the TM and TE signals are obtained with sub-pixel resolution, and the birefringence is proportional to the spacing between these two maxima, with coefficients determined as described above by the device parameters.

[0044] Related to the requirement for accurate intensity extraction, the device includes several enhancements, such as a light-scattering surface (static diffuser) adjacent to or on the prism entrance surface to improve the angular uniformity of the illumination, a moving diffuser for speckle reduction when the light source is coherent or partially coherent, and a light-absorbing coating on portions of the input and output faces of the prism as well as on the sides of the prism to reduce parasitic background that tends to distort the intensity signal. Additionally, the device may include an infrared light source to enable measurement of opaque materials.

[0045] Furthermore, Roussev II discloses the extinction coefficients of the samples studied and the wavelength ranges that can be measured using the described method and apparatus enhancements. s λ<250πσ s where α s is the optical attenuation coefficient at the measurement wavelength λ, and σ s is the expected value of stress to be measured with the precision typically required for practical applications. This wide range allows practically important measurements to be obtained at wavelengths where high optical attenuation makes conventional measurement methods inapplicable. For example, Roussev II discloses successful measurements of stress-induced birefringence in opaque white glass-ceramics at a wavelength of 1550 nm, where the attenuation is greater than about 30 dB / mm.

[0046] Although some issues were noted above with the FSM technique at deeper DOL values, FSM is still a useful conventional technique that can be utilized with the understanding that there may be an error range of up to ±20% at deeper DOL values. As used herein, DOL refers to the depth of the compressive stress layer calculated using the FSM technique, while DOC refers to the depth of the compressive stress layer determined by the method described in Roussev I and II.

[0047] As previously mentioned, the glass-based articles described herein may be chemically strengthened by ion exchange, exhibiting stress profiles that differ from those exhibited by known strengthened glasses. During this process, ions at or near the surface of the glass-based article are replaced—or exchanged—with larger ions having the same valence or oxidation state. In those embodiments in which the glass-based article comprises an alkali aluminosilicate glass, the ions in the surface layer of the glass and the larger ions are Li + (when present in glass-based articles), Na + , K. + , Rb + , and C.S. + Alternatively, the monovalent cations in the surface layer are Ag + The cations may be replaced with monovalent cations other than alkali metal cations, such as:

[0048] The ion exchange process is generally carried out by immersing the glass-based article in a molten salt bath (or two or more molten salt baths) containing larger ions to be exchanged for smaller ions in the glass-based article. It should be noted that aqueous salt baths may also be used. Moreover, the bath composition may contain multiple types of larger ions (e.g., Na + and K. +), or a single larger ion. Those skilled in the art will recognize that the parameters of the ion exchange process, including but not limited to, the bath composition and temperature, immersion time, the number of immersions of the glass-based article in the salt bath(s), the use of multiple salt baths, and additional steps such as annealing, washing, etc., generally depend on the composition of the glass-based article (including the structure of the article and any crystalline phases present), and the desired DOL or DOC and CS of the glass-based article resulting from the tempering operation. As an example, ion exchange of a glass-based article may be carried out by immersion of the glass-based article in at least one molten bath containing salts such as, but not limited to, nitrates, sulfates, and chlorides of larger alkali metal ions. Typical nitrates include KNO, NaNO, LiNO, and combinations thereof. The temperature of the molten salt bath typically ranges from about 380°C to about 450°C, while the immersion time ranges from about 15 minutes to about 100 hours, depending on the thickness of the glass, the temperature of the bath, and the diffusivity of the glass. However, temperatures and soaking times other than those stated above may also be used.

[0049] In one or more embodiments, the glass-based article may be immersed in a molten salt bath of 100% NaNO having a temperature of about 370°C to about 480°C. In some embodiments, the glass-based substrate may be immersed in a molten mixed salt bath including about 5% to about 90% KNO and about 10% to about 95% NaNO. In some embodiments, the glass-based substrate may be immersed in a molten mixed salt bath including NaSO and NaNO and having a wider temperature range (e.g., up to about 500°C). In one or more embodiments, the glass-based article may be immersed in a second bath after immersion in the first bath. Immersion in the second bath may include immersion in a molten salt bath with 100% KNO for 15 minutes to 8 hours.

[0050] The ion exchange conditions can be tailored to impart a "spike," i.e., to increase the gradient of the stress profile at or near the surface. This spike can be achieved with a single bath or multiple baths, with the baths having a single composition or a mixture of compositions, due to the unique properties of the glass compositions used in the glass-based articles described herein.

[0051] As shown in FIG. 3, the glass-based article 300 of one or more embodiments has a first surface 302 and a second surface 304 opposite the first surface that define a thickness t. In one or more embodiments, the thickness t can be about 3 millimeters or less (e.g., in a range from about 0.01 millimeters to about 3 millimeters, from about 0.1 millimeters to about 3 millimeters, from about 0.2 millimeters to about 3 millimeters, from about 0.3 millimeters to about 3 millimeters, from about 0.4 millimeters to about 3 millimeters, from about 0.01 millimeters to about 2.5 millimeters, from about 0.01 millimeters to about 2 millimeters, from about 0.01 millimeters to about 1.5 millimeters, from about 0.01 millimeters to about 1 millimeter, from about 0.01 millimeters to about 0.9 millimeters, from about 0.01 millimeters to about 0.8 millimeters, from about 0.01 millimeters to about 0.7 millimeters, from about 0.01 millimeters to about 0.6 millimeters, from about 0.01 millimeters to about 0.5 millimeters, from about 0.1 millimeters to about 0.5 millimeters, or from about 0.3 millimeters to about 0.5 millimeters).

[0052] The glass-based article has a stress profile that extends from a first surface 302 to a second surface 304 (or along the entire thickness, t). In the embodiment shown in Figure 3, a stress profile 312 as measured by Roussev I and II as described herein is shown along with a stress profile 340 estimated by FSM measurement techniques as described herein. The x-axis represents stress values ​​and the y-axis represents depth or thickness within the glass-based article.

[0053] As shown in FIG. 3 , stress profile 312 shows CS layer 315 (having surface CS 310), CT layer 325 (having maximum CT 320), and DOC 317, where stress profile 312 goes from compressive to tensile at 330. CT layer 325 also has an associated depth or length 327 (CT region or layer). Estimated stress profile 340 shows a DOL that is greater than the DOC. As used herein, references to DOC and DOL relate to their respective depths from one surface (either first surface 302 or second surface 304), with the understanding that such DOC or DOL may exist from the other surface.

[0054] Surface CS 310 can be about 150 MPa or greater or about 200 MPa or greater (e.g., about 250 MPa or greater, about 300 MPa or greater, about 400 MPa or greater, about 450 MPa or greater, about 500 MPa or greater, or about 550 MPa or greater). Surface CS 310 can be up to about 900 MPa, up to about 1000 MPa, up to about 1100 MPa, or up to about 1200 MPa. Maximum CT 320 can be about 25 MPa or greater, about 50 MPa or greater, or about 100 MPa or greater (e.g., about 150 MPa or greater, about 200 MPa or greater, about 250 MPa or greater, or about 300 MPa or greater). In some embodiments, the maximum CT 320 may range from about 50 MPa to about 250 MPa (e.g., from about 75 MPa to about 250 MPa, from about 100 MPa to about 250 MPa, from about 150 MPa to about 250 MPa, from about 50 MPa to about 175 MPa, from about 50 MPa to about 150 MPa, or from about 50 MPa to about 100 MPa). The maximum CT 320 may be located in a range from about 0.3·t to about 0.7·t, from about 0.4·t to about 0.6·t, or from about 0.45·t to about 0.55·t. It should be noted that any one or more of the surface CS 310 and the maximum CT 320 will depend on the thickness of the glass-based article. For example, a glass-based article having a thickness of about 0.8 mm may have a maximum CT of about 100 MPa or greater. As the thickness of the glass-based article decreases, the maximum CT may increase. In other words, the maximum CT increases as the thickness decreases (i.e., as the glass-based article becomes thinner).

[0055] In some embodiments, the ratio of maximum CT 320 to surface CS 310 can be in the range of about 0.05 to about 1 (e.g., in the range of about 0.05 to about 0.5, about 0.05 to about 0.3, about 0.05 to about 0.2, about 0.05 to about 0.1, about 0.5 to about 0.8, about 0.5 to about 1, about 0.2 to about 0.5, about 0.3 to about 0.5). In known chemically strengthened glass-based articles, the ratio of maximum CT 320 to surface CS 310 is 0.1 or less. In some embodiments, the surface CS can be 1.5 times (or 2 times or 2.5 times) or more the maximum CT. In some embodiments, the surface CS can be up to about 20 times the maximum CT.

[0056] In one or more embodiments, the stress profile 312 has a maximum C, generally at a surface C 310, which can be found at one or both of the first surface 302 and the second surface 304. In one or more embodiments, the C layer or region 315 extends along a portion of its thickness to a DOC 317. In one or more embodiments, the DOC 317 can be about 0.1·t or greater. For example, the DOC 317 can be about 0.12·t or greater, about 0.14·t or greater, about 0.15·t or greater, about 0.16·t or greater, 0.17·t or greater, 0.18·t or greater, 0.19·t or greater, 0.20·t or greater, about 0.21·t or greater, or up to about 0.25·t. In some embodiments, the DOC 317 is less than the chemical depth 342. Chemical depth 342 may be about 0.4·t or greater, about 0.5·t or greater, about 0.55·t or greater, or about 0.6·t or greater. In one or more embodiments, stress profile 312 may be described as parabolic in shape. In some embodiments, the stress profile along a depth or region of the glass-based article exhibiting tensile stress exhibits a parabolic shape. In one or more particular embodiments, stress profile 312 lacks any flat stress (i.e., compressive or tensile) portion or portion exhibiting substantially constant stress (i.e., compressive or tensile). In some embodiments, the CT region exhibits a stress profile that is substantially free of flat stress or substantially constant stress. In one or more embodiments, all points of stress profile 312 between the thickness ranges of about 0·t to about 0.2·t and greater than 0.8·t (or about 0·t to about 0.3·t and greater than 0.7·t) have a tangent less than about −0.1 MPa / micrometer or greater than about 0.1 MPa / micrometer. In some embodiments, the tangent may be less than about -0.2 MPa / micrometer or greater than about 0.2 MPa / micrometer. In some more particular embodiments, the tangent may be less than about -0.3 MPa / micrometer or greater than about 0.3 MPa / micrometer. In even more particular embodiments, the tangent may be less than about -0.5 MPa / micrometer or greater than about 0.5 MPa / micrometer.In other words, the stress profile of one or more embodiments along these thickness ranges (i.e., from about 0·t to about 0.2·t and greater than 0.8·t, or from about 0·t to about 0.3·t and greater than 0.7·t) excludes points with tangents as described herein. Without being bound by theory, known error functions or quasi-linear stress profiles have points along these thickness ranges (i.e., from about 0·t to about 0.2·t and greater than 0.8·t, or from about 0·t to about 0.3·t and greater than 0.7·t) with tangents of about −0.1 MPa / micrometer to about 0.1 MPa / micrometer, about −0.2 MPa / micrometer to about 0.2 MPa / micrometer, about −0.3 MPa / micrometer to about 0.3 MPa / micrometer, or about −0.5 MPa / micrometer to about 0.5 MPa / micrometer (indicating a flat or zero-gradient stress profile along such thickness ranges, as shown at 220 in FIG. 2 ). The stress profile of one or more embodiments of the present disclosure does not exhibit such a stress profile, as shown in FIG. 3, having a flat or zero gradient stress profile along these thickness ranges.

[0057] In one or more embodiments, the glass-based article exhibits a stress profile having a maximum tangent and a minimum tangent in the thickness ranges of about 0.1·t to 0.3·t and about 0.7·t to 0.9·t. In some cases, the difference between the maximum tangent and the minimum tangent is about 3.5 MP / micrometer or less, about 3 MP / micrometer or less, about 2.5 MP / micrometer or less, or about 2 MP / micrometer or less.

[0058] In one or more embodiments, the stress profile 312 is substantially free of any linear segments extending through the depth of the glass-based article, or along at least a portion of the thickness t. In other words, the stress profile 312 increases or decreases substantially continuously along the thickness t. In some embodiments, the stress profile is substantially free of any linear segments in the depth direction having a length of about 10 micrometers or more, about 50 micrometers or more, about 100 micrometers or more, or about 200 micrometers or more. As used herein, the term "linear" refers to a gradient along the linear segment having a magnitude of less than about 5 MPa / micrometer, or less than about 2 MPa / micrometer. In some embodiments, one or more portions of the stress profile that are substantially free of any linear segments in the depth direction exist at a depth within the glass-based article of about 5 micrometers or more (e.g., 10 micrometers or more, or 15 micrometers or more) from either or both of the first surface or the second surface. For example, along a depth of about 0 micrometers to less than about 5 micrometers from the first surface, the stress profile may include a linear segment, but from a depth of about 5 micrometers or more from the first surface, the stress profile may be substantially free of linear segments.

[0059] In some embodiments, the stress profile may include a linear segment from a depth of about 0t to about 0.1t, and may be substantially free of a linear segment from a depth of about 0.1t to about 0.4t. In some embodiments, the stress profile in the thickness range of about 0t to about 0.1t may have a gradient ranging from about 20 MPa / micrometer to about 200 MPa / micrometer. As described herein, such embodiments may be formed using a single ion exchange process, or multiple (e.g., two or more) ion exchange processes, whereby the bath includes two or more alkali salts or is a mixed alkali salt bath.

[0060] In one or more embodiments, the glass-based article may be described in terms of the shape of the stress profile along the CT region (327 in Figure 3). For example, in some embodiments, the stress profile along the CT region (where the stress is tensile) may be approximated by the formula: In some embodiments, the stress profile along the CT region is given by Equation (1):

[0061]

number

[0062] In equation (1), Stress(x) is the stress value at location x, where Stress is positive (tension). MaxCT is the maximum central tension as a positive value expressed in MPa. The value x is the location along the thickness (t) in micrometers and ranges from 0 to t; x=0 is one surface (302 in FIG. 3), x=0.5t is the center of the glass-based article, and Stress(x)=MaxCT, x=t is the opposite surface (304 in FIG. 3). The MaxCT used in equation (1) can range from about 50 MPa to about 350 MPa (e.g., 60 MPa to about 300 MPa, or about 70 MPa to about 270 MPa), and n is an approximation parameter from 1.5 to 5 (e.g., from 2 to 4, from 2 to 3, or from 1.8 to 2.2), whereby n=2 can give a parabolic stress profile, and exponents that deviate from n=2 give the stress profile a near-parabolic stress profile. Figure 39 shows example stress profiles for various combinations of MaxCT and n (from 1.5 to 5, as indicated in the legend) for a 0.8 mm thick glass-based article.

[0063] In some embodiments, the stress profile may be altered by heat treatment. In such embodiments, the heat treatment may occur before any ion-exchange process, during any ion-exchange process, or after all ion-exchange processes. In some embodiments, the heat treatment may reduce the slope of the stress profile at or near the surface. In some embodiments where a steeper or larger slope is desired at the surface, an ion-exchange process after the heat treatment may be used to provide a "spike" at or near the surface, i.e., increase the slope of the stress profile.

[0064] In one or more embodiments, the stress profile 312 (and / or estimated stress profile 340) results from a non-zero concentration of metal oxide that varies along a portion of the thickness. The concentration variation may be referred to herein as a gradient. In some embodiments, the metal oxide concentration varies non-zero along a thickness range of about 0·t to about 0.3·t. In some embodiments, the metal oxide concentration varies non-zero along a thickness range of about 0·t to about 0.35·t, about 0·t to about 0.4·t, about 0·t to about 0.45·t, or about 0·t to about 0.48·t. The metal oxide may be described as inducing stress in the glass-based article. The concentration variation may be continuous along the thickness range described above. The concentration variation may include a change of about 0.2 mol % in metal oxide concentration along a thickness segment of about 100 micrometers. This variation may be measured by methods known in the art, including a microprobe, as shown in Example 1. Metal oxides that have non-zero concentrations that vary along a portion of the thickness may be described as causing stress in the glass-based article.

[0065] The concentration variation can be continuous along the thickness ranges described above. In some embodiments, the concentration variation can be continuous along a thickness segment ranging from about 10 micrometers to about 30 micrometers. In some embodiments, the concentration of the metal oxide decreases from the first surface to a point between the first surface and the second surface, and then increases from that point to the second surface.

[0066] The metal oxide concentration may include multiple metal oxides (e.g., a combination of NaO and KO). In some embodiments where two metal oxides are utilized and the ions have different radii, the concentration of the ions with larger radii is greater than the concentration of the ions with smaller radii at shallower depths, while at greater depths the concentration of the smaller ions with larger radii is greater than the concentration of the larger ions. For example, if a single Na- and K-containing bath is used in the ion exchange process, the concentration of K in the glass-based article may be greater than the concentration of the smaller ions with larger radii. + The concentration of ions is higher at shallower depths than Na + ions, whereas at deeper depths, Na + The concentration of ions is K + The concentration of ions is greater than the concentration of ions at the surface. This is due, in part, to the size of the ions. In such glass-based articles, areas at or near the surface have a larger CS due to the greater amount of larger ions at or near the surface. This larger CS would be manifested by a stress profile at or near the surface having a steeper slope (i.e., a spike in the stress profile at the surface).

[0067] The concentration gradient or variation of one or more metal oxides is created by chemically strengthening the glass-based article, for example, by the ion exchange process described previously herein, in which a plurality of first metal ions in the glass-based article are exchanged for a plurality of second metal ions. The first metal ions can be ions of lithium, sodium, potassium, and rubidium. The second metal ions can be ions of one of sodium, potassium, rubidium, and cesium, provided that the second alkali metal ion has an ionic radius larger than the ionic radius of the first alkali metal ion. The second metal ions are present in the glass-based substrate as their oxides (e.g., Na2O, KO, Rb2O, Cs2O, or combinations thereof).

[0068] In one or more embodiments, a concentration gradient of the metal oxide extends through a substantial portion of the thickness t or the entire thickness t of the glass-based article including the CT layer 325. In one or more embodiments, the concentration of the metal oxide is about 0.5 mol % or greater in the CT layer 325. In some embodiments, the concentration of the metal oxide can be about 0.5 mol % or greater (e.g., about 1 mol % or greater) along the entire thickness of the glass-based article, being greatest at the first surface 302 and / or the second surface 304 and decreasing substantially constantly to a point between the first surface 302 and the second surface 304. At that point, the concentration of the metal oxide is minimum along the entire thickness t; however, the concentration is also non-zero at that point. In other words, a non-zero concentration of the particular metal oxide extends along a substantial portion of the thickness t (as described herein) or the entire thickness t. In some embodiments, the lowest concentration of the particular metal oxide is in the CT layer 327. The total concentration of a particular metal oxide in the glass-based article may range from about 1 mole % to about 20 mole %.

[0069] In one or more embodiments, the glass-based article has a first metal oxide concentration and a second metal oxide concentration, where the first metal oxide concentration ranges from about 0 mol% to about 15 mol% along a first thickness range of about 0t to about 0.5t, and the second metal oxide concentration ranges from about 0 mol% to about 10 mol% along a second thickness range of about 0 micrometers to about 25 micrometers (or about 0 micrometers to about 12 micrometers). The glass-based article may have an optional third metal oxide concentration. The first metal oxide may include NaO, and the second metal oxide may include KO.

[0070] The concentration of said metal oxide may be determined from a base amount of metal oxide in the glass-based article before it is altered to include a concentration gradient of such metal oxide.

[0071] In one or more embodiments, the glass-based articles may be described in terms of how they break and the fragments resulting from such breakage. In one or more embodiments, when a glass-based article breaks, it breaks into two or more pieces per square inch (or per 6.4516 square centimeters). In some cases, the glass-based article breaks into three or more, four or more, five or more, or ten or more pieces per square inch (or per 6.4516 square centimeters) of the glass-based article (prior to breakage). In some cases, when a glass-based article breaks, it breaks into fragments such that 50% or more of the fragments have a surface area that is less than 5%, less than 2%, or less than 1% of the surface area of ​​the glass-based article (prior to breakage). In some embodiments, when a glass-based article breaks, it breaks into fragments such that 90% or more or even 100% of the fragments have a surface area that is less than 5%, less than 2%, or less than 1% of the surface area of ​​the glass-based article (prior to breakage).

[0072] In one or more embodiments, after chemically strengthening the glass-based article, the resulting stress profile 312 (and estimated stress profile 340) of the glass-based article provides improved fracture resistance. For example, in some embodiments, the glass-based article, upon fracture, comprises fragments having an average longest cross-sectional dimension of about 2·t or less (e.g., 1.8·t, 1.6·t, 1.5·t, 1.4·t, 1.2·t, or 1·t or less).

[0073] In one or more embodiments, the glass-based article has a compressibility of about 0.7 MPa m 1 / 2 Fracture toughness (K 1C In some cases, the fracture toughness is about 0.8 MPa m 1 / 2 or more, or approximately 0.9 MPa m 1 / 2 In some embodiments, the fracture toughness is about 0.7 MPa m 1 / 2 to approximately 1 MPa m 1 / 2 may be in the range of

[0074] In some embodiments, the substrate may be characterized as having a hardness of about 500 HVN to about 800 HVN as measured by the Vickers hardness test under a 200 g load.

[0075] The glass-based articles described herein have a thermal conductivity of 0 J / m 2 Over 20J / m 2 In some cases, the stored tensile energy is about 1 J / m 2 to about 20 J / m 2 , about 2J / m 2 to about 20 J / m 2 , about 3J / m 2 to about 20 J / m 2 , about 4J / m 2 to about 20 J / m 2 , about 1J / m 2 to approximately 19 J / m 2 , about 1J / m 2 to approximately 18 J / m 2 , about 1J / m 2 to approximately 16 J / m2 , about 4J / m 2 to about 20 J / m 2 , or about 4 J / m 2 to approximately 18 J / m 2 The stored tensile energy can be in the range of .

[0076]

number

[0077] is formed by integrating the stored elastic energy Σ per unit area of ​​the sample of thickness t in the tensile region using the equation, where σ is the stress and E is Young's modulus.

[0078] More specifically, the stored tensile energy is calculated according to the following equation (3):

[0079]

number

[0080] where n is Poisson's ratio, E is the elastic modulus, and the integral is calculated over the tension region only.

[0081] In one or more embodiments, the glass-based article exhibits improved surface strength when subjected to a Ring-on-Ring Abrasion (AROR) testing. The strength of a material is defined as the stress at which fracture occurs. The A-ROR test is a surface strength measurement for testing flat glass specimens, and 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 Ring-on-Ring Abrasion ROR test method described herein. The contents of ASTM C1499-09 are incorporated herein by reference in their entirety. In one embodiment, the glass specimens are abraded with 90-grit silicon carbide (SiC) particles delivered to the glass sample using the method and apparatus described in Annex A2, entitled "Abrasion Procedures," of ASTM C158-02(2012), entitled "Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)," prior to ring-on-ring testing. The contents of ASTM C158-02, and particularly Annex 2, are incorporated herein by reference in their entirety.

[0082] Prior to ring-on-ring testing, the surface of the glass-based article is abraded as described in ASTM C158-02, Annex 2, using the apparatus shown in Figure A2.1 of ASTM C158-02 to standardize and / or control the surface defect condition of the sample. The abrasive is blasted onto the surface 110 of the glass-based article at a load of 15 psi (approximately 103 kPa) using an air pressure of 304 kPa (44 psi); however, in the examples below, the abrasive was blasted onto the surface 110 at loads of 25 psi (approximately 172 kPa) and 45 psi (approximately 310 kPa). After the airflow was established, the abrasive was blasted onto the surface 110 at a load of 5 cm. 3 of abrasive is placed in the funnel and the sample is sandblasted for 5 seconds after the introduction of the abrasive.

[0083] For ring-on-ring testing, a glass sample 410 having at least one polished surface, as shown in Figure 4, is placed between two concentric rings of different sizes, also shown in Figure 4, to determine the equibiaxial bending strength (i.e., the maximum stress the material can sustain when subjected to bending between two concentric rings). In the ring-on-ring as-polished configuration 400, the polished glass-based article 410 is supported by a support ring 420 having a diameter D2. A force F is applied by a load cell (not shown) to the surface of the glass-based article by a loading ring 430 having a diameter D1.

[0084] The diameter ratio D1 / D2 of the load ring to the support ring will be in the range of about 0.2 to about 0.5. In some embodiments, D1 / D2 is about 0.5. The load and support rings 430, 420 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. In some embodiments, testing is performed at a temperature of 23±2°C and a relative humidity of 40±10%.

[0085] For the design of the instrument, the radius r of the protruding surface of the load ring 430 is h / 2≦r≦3h / 2, where h is the thickness of the glass-based article 410. The load and support rings 430, 420 are generally made of a material having a hardness of HR c Made from hardened steel >40. ROR instruments are commercially available.

[0086] The objective failure mechanism of the ROR test is to observe cracking of the glass-based article 410 originating from surface 430a within the loading ring 430. Failures occurring outside of this region—i.e., between the loading ring 430 and the support ring 420—are excluded from data analysis. However, due to the thinness and high strength of the glass-based article 410, large deflections exceeding one-half the specimen thickness h can be observed. Therefore, it is not uncommon to observe a high percentage of failures originating from below the loading ring 430. Without knowing the stress development both inside and below the ring (gathered via strain gauge analysis) and the point of failure initiation for each specimen, stress cannot be accurately calculated. Therefore, the ROR test focuses on the maximum load at failure as the measured response.

[0087] The strength of glass-based articles depends on the presence of surface flaws. However, because the strength of glass is statistical in nature, the tendency for flaws of a given size to exist cannot be accurately predicted. Therefore, probability distributions can generally be used as statistical representations of the data obtained.

[0088] In some embodiments, the strengthened glass-based articles described herein have a surface or equibiaxial flexural strength of at least 20 kgf (about 196 N) and up to about 30 kgf (about 294 N), as determined by a ring-on-ring test while abrading using a load of 25 psi (about 172 kPa) or even 45 psi (about 310 kPa) to abrade the surface. The surface strength is at least 25 kgf (about 245 N) in other embodiments, and at least 30 kgf (about 294 N) in still other embodiments.

[0089] In some embodiments, the strengthened glass-based articles described herein may be described in terms of their performance in an inverted ball-on-sandpaper (IBoS) test. The IBoS test is a dynamic, component-level test that mimics the dominant mechanism of failure due to damage introduction and bending that typically occurs in glass-based articles used in portable or handheld electronic devices, as shown generally in FIG. 36. In the field, damage introduction occurs at the top surface of the glass-based article (FIG. 37a). A crack initiates at the top surface of the glass-based article, and either the damage penetrates the glass-based article (FIG. 37b), or the crack propagates from the bending of the top surface or from within the glass-based article (FIG. 37c). The IBoS test is designed to simultaneously introduce damage to the surface of the glass and apply bending under dynamic load. In some cases, the glass-based article exhibits improved drop performance when it contains compressive stress compared to the same glass-based article without compressive stress.

[0090] The IBoS testing apparatus is shown schematically in FIG. 36. The apparatus 500 includes a test stand 510 and a ball 530. The ball 530 is a rigid or solid ball, such as a stainless steel ball. In one embodiment, the ball 530 is a 10 mm diameter, 4.2 gram stainless steel ball. The ball 530 is dropped directly onto the glass-based article sample 518 from a predetermined height h. The test stand 510 includes a solid base 512 made of a hard, rigid material, such as granite. An abrasive-covered sheet 514 is placed on top of the solid base 512 with the abrasive-covered surface facing upward. In some embodiments, the sheet 514 is abrasive paper with a 30-grit surface, and in other embodiments, a 180-grit surface. The glass-based article sample 518 is held in place on the sheet 514 by a sample holder 515 such that a gap 516 exists between the glass-based article sample 518 and the sheet 514. An air gap 516 between the glass sheet 514 and the glass-based article sample 518 allows the glass-based article sample 518 to bend upon impact of the ball 530 on the polished surface of the sheet 514. In one embodiment, the glass-based article sample 518 is clamped at all corners to constrain bending only to the point of ball impact and ensure repeatability. In some embodiments, the sample holder 515 and test stand 510 are adapted to accommodate sample thicknesses up to about 2 mm. The air gap 516 ranges from about 50 μm to about 100 μm. The air gap 516 is adapted to adjust for differences in material stiffness (Young's modulus, EMod), including the sample's elastic modulus and thickness. Adhesive tape 520 may be used to cover the top surface of the glass-based article sample 518 to collect fragments in the event of a breakage of the glass-based article sample 518 upon impact of the ball 530.

[0091] A variety of materials may be used as the abrasive surface. In one particular embodiment, the abrasive surface is abrasive paper, such as silicon carbide or alumina abrasive paper, industrial abrasive paper, or any abrasive known to those skilled in the art to have comparable hardness and / or sharpness. In some embodiments, abrasive paper with 30 grit may be used, as it has a more consistent surface topography than either concrete or asphalt, as well as a grain size and sharpness that produces the desired level of surface damage to the sample.

[0092] In one embodiment, a method 600 for conducting an IBoS test using the previously described apparatus 500 is shown in FIG. 38. In step 610, a glass-based article sample (518 in FIG. 36) previously described and secured in a sample holder 515 is placed in a test stand 510 such that a gap 516 is formed between the glass-based article sample 518 and the sheet 514 having an abrasive surface. Method 600 assumes that the sheet 514 having an abrasive surface has already been placed in the test stand 510. However, in some embodiments, the method may include placing the sheet 514 in the test stand 510 with the abrasive surface facing upward. In some embodiments (step 610a), adhesive tape 520 is applied to the top surface of the glass-based article sample 518 before the glass-based article sample 518 is secured in the sample holder 515.

[0093] In step 620, a solid sphere 530 of predetermined mass and size is dropped from a predetermined height h onto the top surface of the glass-based article sample 518 so that the sphere 530 impacts the top surface approximately at the center of the top surface (i.e., within 1 mm, or within 3 mm, or within 5 mm, or within 10 mm of the center). After the impact in step 620, the extent of damage to the glass-based article sample 518 is determined (step 630). As previously stated, the term "crack" as used herein means that a crack propagates through the entire thickness and / or surface of a substrate when the substrate is dropped or impacted by an object.

[0094] In method 600, the sheet 514 having an abrasive surface may be replaced after each drop to avoid the "aging" hardening that has been observed with repeated use of other types of drop test surfaces (e.g., concrete or asphalt).

[0095] Various predetermined drop heights h and increments are commonly used in method 600. The test may, for example, initially use a minimum drop height (e.g., about 10-20 cm). This height may then be increased for successive drops by either a prescribed increment or a variable increment. The test described in method 600 stops once the glass-based article sample 518 breaks or cracks (step 631). Alternatively, the drop test in method 600 may stop once the drop height h reaches a maximum drop height (e.g., about 100 cm) without cracking, or step 620 may be repeated at that maximum height until cracking occurs.

[0096] In some embodiments, the IBoS test of method 600 is performed only once on each glass-based article sample 518 at each predetermined height h. However, in other embodiments, multiple tests may be performed on each sample at each height.

[0097] If cracking of the glass-based article sample 518 occurs (step 631 in FIG. 38 ), IBoS testing according to method 600 ends (step 640). If no cracking is observed upon dropping the ball at the predetermined drop height (step 632), the drop height is increased by a predetermined increment, e.g., 5, 10, or 20 cm (step 634), and steps 620 and 630 are repeated until either cracking of the sample is observed (step 631) or the maximum test height is reached without the sample cracking (step 636). Once either step 631 or 636 is reached, testing according to method 600 ends.

[0098] When subjected to the inverted ball on sandpaper (IBoS) test described above, embodiments of the glass-based articles described herein have a survival rate of at least about 60% when a ball is dropped onto a glass surface from a height of 100 cm. For example, a glass-based article is said to have a 60% survival rate when dropped from a given height (here, 100 cm) if three out of five identical (or nearly identical) samples (i.e., having substantially the same composition and, when tempered as described herein, having substantially the same compressive stress and compressive or compressive stress layer depth) survive the IBoS test without cracking. In other embodiments, the survival rate of the tempered glass-based article in the 100 cm IBoS test is at least about 70%, in other embodiments at least about 80%, and in still other embodiments at least about 90%. In other embodiments, the survival rate of a tempered glass-based article dropped from a height of 100 cm in the IBoS test is at least about 60%, in other embodiments at least about 70%, in still other embodiments at least about 80%, and in other embodiments at least about 90%. In one or more embodiments, the survival rate of a tempered glass-based article dropped from a height of 150 cm in the IBoS test is at least about 60%, in other embodiments at least about 70%, in still other embodiments at least about 80%, and in other embodiments at least about 90%.

[0099] To determine the survival rate of a glass-based article when dropped from a predetermined height using the IBoS test method and apparatus described above, at least five identical (or nearly identical) samples of the glass-based article (i.e., having approximately the same composition and approximately the same compressive stress and compression or depth of layer) are tested, although a greater number of samples (e.g., 10, 20, 30, etc.) may be tested to increase the confidence level of the test results. Each sample is dropped once from the predetermined height (e.g., 100 cm or 150 cm) or dropped from progressively higher heights without breaking until the predetermined height is reached, and then visually (i.e., with the naked eye) examined for evidence of cracking (the formation and propagation of a crack throughout the entire thickness and / or surface of the sample). If no cracks are observed after the drop from the predetermined height, the sample is considered to have "survived" the drop test; if cracks are observed when the sample is dropped from a height below the predetermined height, the sample is considered to have "failed" (or "did not survive"). Survival is determined as the percentage of sample population that survives the drop test. For example, if 7 samples out of a group of 10 samples do not break when dropped from a given height, the survival rate of the glass would be 70%.

[0100] The glass-based articles described herein may be transparent or opaque. In one or more embodiments, the glass-based articles may have a thickness of about 1 millimeter or less and exhibit a transmittance of about 88% or greater over a wavelength range of about 380 nm to about 780 nm. In other embodiments, the glass-based articles may have a thickness of about 1 millimeter or less and exhibit a transmittance of about 10% or less over a wavelength range of about 380 nm to about 780 nm.

[0101] The glass-based article may also exhibit a substantially white color. For example, the glass-based article may have an L of about 88 or greater under CIE illuminant F02. * Values, a range from about -3 to about +3 * values, and b in the range of about -6 to about +6 *Alternatively, the glass-based article may have an L of about 40 or less under CIE illuminant F02. * Values, a range from about -3 to about +3 * values, and b in the range of about -6 to about +6 * The CIELAB color space coordinates of the color values ​​may also exist under other CIE illuminants (e.g., D65).

[0102] The choice of substrate is not particularly limited. In some instances, glass-based articles may be described as having high cation diffusivity due to ion exchange. In one or more embodiments, the glass or glass-ceramic has a fast ion exchange capacity, i.e., a diffusivity of 500 μm or greater. 2 / hr or 450μm at 460℃ 2 It may be characterized as over / hours.

[0103] At a particular temperature, the diffusivity is given by equation (4):

[0104]

number

[0105] where DOL is the depth of the ion exchange layer and T is the ion exchange time taken to reach that DOL.

[0106] The glass-based article may include an amorphous substrate, a crystalline substrate, or a combination thereof (e.g., a glass-ceramic substrate). In one or more embodiments, the substrate of the glass-based article (before being chemically strengthened as described herein) may comprise a glass having a composition, expressed in mole percent (mol%), including SiO in the range of about 40 to about 80, AlO in the range of about 10 to about 30, BO in the range of about 0 to about 10, RO in the range of about 0 to about 20, and RO in the range of about 0 to about 15. In some cases, the composition may include either or both of ZrO in the range of about 0 mol% to about 5 mol% and PO in the range of about 0 mol% to about 15 mol%. TiO may be present at about 0 mol% to about 2 mol%.

[0107] In some embodiments, the glass composition may include SiO in an amount, expressed as mole percent, ranging from about 45 to about 80, about 45 to about 75, about 45 to about 70, about 45 to about 65, about 45 to about 60, about 50 to about 70, about 55 to about 70, about 60 to about 70, about 70 to about 75, about 70 to about 72, or about 50 to about 65.

[0108] In some embodiments, the glass composition may include Al2O3 in an amount, expressed in mole percent, ranging from about 5 to about 28, from about 5 to about 26, from about 5 to about 25, from about 5 to about 24, from about 5 to about 22, from about 5 to about 20, from about 6 to about 30, from about 8 to about 30, from about 10 to about 30, from about 12 to about 30, from about 14 to about 30, from about 16 to about 30, from about 18 to about 30, from about 18 to about 28, or from about 12 to about 15.

[0109] In one or more embodiments, the glass composition may contain B2O3 in an amount, expressed in mole percent, ranging from about 0 to about 8, about 0 to about 6, about 0 to about 4, about 0.1 to about 8, about 0.1 to about 6, about 0.1 to about 4, about 1 to about 10, about 2 to about 10, about 4 to about 10, about 2 to about 8, about 0.1 to about 5, or about 1 to about 3. In some cases, the glass composition may be substantially free of B2O3. As used herein, the phrase "substantially free" with respect to a component of a glass composition means that the component is not actively or intentionally added to the glass composition during initial batch formulation or subsequent ion exchange, but may be present as an impurity. For example, a glass may be described as substantially free of a component if the component is present in an amount less than about 0.1001 mole percent.

[0110] In some embodiments, the glass composition may include one or more alkaline earth metal oxides, such as MgO, CaO, and ZnO. In some embodiments, the total amount of the one or more alkaline earth metal oxides may be a non-zero amount to about 15 mol%. In one or more particular embodiments, the total amount of any of the alkaline earth metal oxides may be a non-zero amount to about 14 mol%, about 12 mol%, about 10 mol%, about 8 mol%, about 6 mol%, about 4 mol%, about 2 mol%, or about 1.5 mol%. In some embodiments, the total amount, expressed in mol%, of the one or more alkaline earth metal oxides may be in the range of about 0.1 to 10, about 0.1 to 8, about 0.1 to 6, about 0.1 to 5, about 1 to 10, about 2 to 10, or about 2.5 to 8. The amount of MgO may be in the range of about 0 mol% to about 5 mol% (e.g., about 2 mol% to about 4 mol%). The amount of ZnO may range from about 0 mol% to about 2 mol%. The amount of CaO may range from about 0 mol% to about 2 mol%. In one or more embodiments, the glass composition may include MgO and may be substantially free of CaO and ZnO. In one variation, the glass composition may include either CaO or ZnO and may be substantially free of the others of MgO, CaO, and ZnO. In one or more particular embodiments, the glass composition may include only two of the alkaline earth metal oxides, MgO, CaO, and ZnO, and may be substantially free of the third alkaline earth metal oxide.

[0111] The total amount of alkali metal oxides R2O, expressed in mole percent, in the glass composition can be in the range of about 5 to about 20, about 5 to about 18, about 5 to about 16, about 5 to about 15, about 5 to about 14, about 5 to about 12, about 5 to about 10, about 5 to about 8, about 6 to about 20, about 7 to about 20, about 8 to about 20, about 9 to about 20, about 10 to about 20, about 6 to about 13, or about 8 to about 12.

[0112] In one or more embodiments, the glass composition includes NaO in an amount ranging from about 0 mol% to about 18 mol%, from about 0 mol% to about 16 mol%, from about 0 mol% to about 14 mol%, from about 0 mol% to about 10 mol%, from about 0 mol% to about 5 mol%, from about 0 mol% to about 2 mol%, from about 0.1 mol% to about 6 mol%, from about 0.1 mol% to about 5 mol%, from about 1 mol% to about 5 mol%, from about 2 mol% to about 5 mol%, or from about 10 mol% to about 20 mol%.

[0113] In some embodiments, the amounts of Li2O and Na2O are controlled to specific amounts or ratios to balance formability and ion-exchangeability. For example, as the amount of Li2O increases, the liquidus viscosity may decrease, thereby making certain forming methods unusable; however, such glass compositions may be ion-exchanged to deeper DOC levels as described herein. The amount of Na2O can alter the liquidus viscosity but may inhibit ion-exchange to deeper DOC levels.

[0114] In one or more embodiments, the glass composition may include KO in an amount less than about 5 mol%, less than about 4 mol%, less than about 3 mol%, less than about 2 mol%, or less than about 1 mol%. In one or more alternative embodiments, the glass composition may be substantially free of KO, as defined herein.

[0115] In one or more embodiments, the glass composition may include LiO in an amount from about 0 mol% to about 18 mol%, from about 0 mol% to about 15 mol%, or from about 0 mol% to about 10 mol%, from about 0 mol% to about 8 mol%, from about 0 mol% to about 6 mol%, from about 0 mol% to about 4 mol%, or from about 0 mol% to about 2 mol%. In some embodiments, the glass composition may include LiO in an amount from about 2 mol% to about 10 mol%, from about 4 mol% to about 10 mol%, from about 6 mol% to about 10 mol%, or from about 5 mol% to about 8 mol%. In one or more alternative embodiments, the glass composition may be substantially free of LiO, as defined herein.

[0116] In one or more embodiments, the glass composition may include FeO. In such embodiments, FeO may be present in an amount less than about 1 mol%, less than about 0.9 mol%, less than about 0.8 mol%, less than about 0.7 mol%, less than about 0.6 mol%, less than about 0.5 mol%, less than about 0.4 mol%, less than about 0.3 mol%, less than about 0.2 mol%, less than about 0.1 mol%, and all ranges and sub-ranges therebetween. In one or more alternative embodiments, the glass composition may be substantially free of FeO, as defined herein.

[0117] In one or more embodiments, the glass composition may include ZrO. In such embodiments, ZrO may be present in an amount less than about 1 mol%, less than about 0.9 mol%, less than about 0.8 mol%, less than about 0.7 mol%, less than about 0.6 mol%, less than about 0.5 mol%, less than about 0.4 mol%, less than about 0.3 mol%, less than about 0.2 mol%, less than about 0.1 mol%, and all ranges and sub-ranges therebetween. In one or more alternative embodiments, the glass composition may be substantially free of ZrO, as defined herein.

[0118] In one or more embodiments, the glass composition may include P2O5 in the range of about 0 mol% to about 10 mol%, about 0 mol% to about 8 mol%, about 0 mol% to about 6 mol%, about 0 mol% to about 4 mol%, about 0.1 mol% to about 10 mol%, about 0.1 mol% to about 8 mol%, about 4 mol% to about 8 mol%, or about 5 mol% to about 8 mol%. In some cases, the glass composition may be substantially free of P2O5.

[0119] In one or more embodiments, the glass composition may include TiO. In such embodiments, TiO may be present in an amount less than about 6 mol%, less than about 4 mol%, less than about 2 mol%, or less than about 1 mol%. In one or more alternative embodiments, the glass composition may be substantially free of TiO, as defined herein. In some embodiments, TiO is present in an amount ranging from about 0.1 mol% to about 6 mol%, or from about 0.1 mol% to about 4 mol%.

[0120] In some embodiments, the glass composition may include various compositional relationships. For example, the glass composition may include a ratio of the amount (mol %) of LiO to the total amount (mol %) of R0 ranging from about 0.5 to about 1. In some embodiments, the glass composition may include a difference in the total amount (mol %) of R0 to the amount (mol %) of Al2O3 ranging from about -5 to about 0. In some cases, the glass composition may include a difference in the total amount (mol %) of R0 to the amount (mol %) of Al2O3 ranging from about 0 to about 3. x The glass composition of one or more embodiments may exhibit a ratio of the amount of MgO (mol %) to the total amount of RO (mol %) ranging from about 0 to about 2.

[0121] In some embodiments, the glass composition may be substantially free of nucleating agents. Typical examples of nucleating agents include TiO2, ZrO2, etc. Nucleating agents are sometimes described in terms of their function as components in a glass that can initiate the formation of crystallites in the glass.

[0122] In some embodiments, the composition used in the glass substrate may include 0-2 mol% of at least one fining agent selected from the group including Na2SO4, NaCl, NaF, NaBr, K2SO4, KCl, KF, KBr, and SnO2. Glass compositions according to one or more embodiments may further include SnO2 in the range of about 0 to about 2, about 0 to about 1, about 0.1 to about 2, about 0.1 to about 1, or about 1 to about 2. The glass compositions disclosed herein may be substantially free of As2O3 and / or Sb2O3.

[0123] In one or more embodiments, the composition may specifically comprise 62 mol% to 75 mol% SiO, 10.5 mol% to about 17 mol% AlO, 5 mol% to about 13 mol% LiO, 0 mol% to about 4 mol% ZnO, 0 mol% to about 8 mol% MgO, 2 mol% to about 5 mol% TiO, 0 mol% to about 4 mol% BO, 0 mol% to about 5 mol% NaO, 0 mol% to about 4 mol% KO, 0 mol% to about 2 mol% ZrO, 0 mol% to about 7 mol% PO, 0 mol% to about 0.3 mol% FeO, 0 mol% to about 2 mol% MnO, x and 0.05 mol% to about 0.2 mol% SnO2. In one or more embodiments, the composition may include 67 mol% to about 74 mol% SiO2, 11 mol% to about 15 mol% Al2O3, 5.5 mol% to about 9 mol% Li2O, 0.5 mol% to about 2 mol% ZnO, 2 mol% to about 4.5 mol% MgO, 3 mol% to about 4.5 mol% TiO2, 0 mol% to about 2.2 mol% B2O3, 0 mol% to about 1 mol% Na2O, 0 mol% to about 1 mol% K2O, 0 mol% to about 1 mol% ZrO2, 0 mol% to about 4 mol% PO5, 0 mol% to about 0.1 mol% Fe2O3, 0 mol% to about 1.5 mol% MnO xand 0.08 mol% to about 0.16 mol% SnO2. In one or more embodiments, the composition may include 70 mol% to 75 mol% SiO2, 10 mol% to about 15 mol% Al2O3, 5 mol% to about 13 mol% Li2O, 0 mol% to about 4 mol% ZnO, 0.1 mol% to about 8 mol% MgO, 0 mol% to about 5 mol% TiO2, 0.1 mol% to about 4 mol% B2O3, 0.1 mol% to about 5 mol% Na2O, 0 mol% to about 4 mol% K2O, 0 mol% to about 2 mol% ZrO2, 0 mol% to about 7 mol% PO5, 0 mol% to about 0.3 mol% Fe2O3, 0 mol% to about 2 mol% MnO x and 0.05 mol % to about 0.2 mol % SnO2.

[0124] In one or more embodiments, the composition comprises 52 mol% to about 63 mol% SiO, 11 mol% to about 15 mol% AlO, 5.5 mol% to about 9 mol% LiO, 0.5 mol% to about 2 mol% ZnO, 2 mol% to about 4.5 mol% MgO, 3 mol% to about 4.5 mol% TiO, 0 mol% to about 2.2 mol% BO, 0 mol% to about 1 mol% NaO, 0 mol% to about 1 mol% KO, 0 mol% to about 1 mol% ZrO, 0 mol% to about 4 mol% PO, 0 mol% to about 0.1 mol% FeO, 0 mol% to about 1.5 mol% MnO. x , and 0.08 mol % to about 0.16 mol % SnO2.

[0125] Other exemplary compositions of glass-based articles, as described herein, before being chemically strengthened are shown in Table 1.

[0126] [Table 1-1]

[0127] [Table 1-2]

[0128] When the glass-based article comprises a glass-ceramic, the crystalline phases may include beta-spodumene, rutile, gahnite, or other known crystalline phases and combinations thereof.

[0129] The glass-based article may be substantially planar, although other embodiments may use curved or otherwise shaped or shaped substrates. In some cases, the glass-based article may have a 3D or 2.5D shape. The glass-based article may be substantially optically clear, transparent, and free of light scattering. The glass-based article may have a refractive index ranging from about 1.45 to about 1.55. As used herein, refractive index values ​​refer to a wavelength of 550 nm.

[0130] Additionally, or alternatively, the thickness of the glass-based article may be constant along one or more dimensions, or may vary along one or more of its dimensions for aesthetic and / or functional reasons. For example, the edges of the glass-based article may be thicker than more central regions of the glass composition. The length, width, and thickness dimensions of the glass-based article may also vary depending on the application or use of the article.

[0131] The glass-based article may be characterized by the manner in which it is formed. For example, a glass-based article may be characterized as float-formable (i.e., formed by a float process), down-drawable, and particularly fusion-formable or slot-drawable (i.e., formed by a down-draw process such as a fusion draw process or a slot draw process).

[0132] Float-formable glass-based articles may be characterized by a smooth surface and uniform thickness and are produced by floating molten glass on a bed of molten metal, typically tin. In an exemplary process, molten glass fed to the surface of the molten tin bed forms a floating glass ribbon. As this glass ribbon flows along the tin bath, its temperature gradually decreases until the glass ribbon solidifies into a solid glass-based article that is lifted from the tin onto rollers. Once removed from the bath, the glass-based article can be further cooled and annealed to reduce internal stresses. If the glass-based article is a glass-ceramic, the glass-based article formed by the float process may be subjected to a ceramming process, whereby one or more crystalline phases are produced.

[0133] The down-draw process produces glass-based articles of uniform thickness with relatively pristine surfaces. Because the average flexural strength of a glass-based article is controlled by the amount and size of surface flaws, pristine surfaces with minimal contact have higher initial strength. When this high-strength glass-based article is then further strengthened (e.g., chemically), the resulting strength can be greater than that of glass-based articles with lapped and polished surfaces. Down-drawn glass-based articles can be drawn to thicknesses of less than about 2 mm. Furthermore, down-drawn glass-based articles have very flat and smooth surfaces that can be used in their final applications without costly grinding and polishing. If the glass-based article is a glass-ceramic, the glass-based article formed by the down-draw process may be subjected to a ceramming process, which produces one or more crystalline phases.

[0134] The fusion draw process, for example, uses a drawing tank having a passageway for receiving molten glass raw material. The passageway has weirs on both sides of the passageway that are open at the top along the length of the passageway. When the passageway is filled with molten material, the molten glass overflows the weirs. The molten glass flows down the exterior surface of the drawing tank due to gravity as two flowing glass films. These exterior surfaces of the drawing tank extend downward and inward to meet at the lower edge of the drawing tank. The two flowing glass films meet at this edge and fuse to form a single flowing glass-based article. This fusion draw process offers the advantage that because the two glass films flowing over the passageway fuse together, the exterior surface of the resulting glass-based article does not come into contact with any part of the equipment. Therefore, the surface properties of the glass-based article formed by the fusion draw process are not affected by such contact. If the glass-based article is a glass-ceramic, the glass-based article formed by the fusion process may be subjected to a ceramming process, whereby one or more crystalline phases are produced.

[0135] The slot draw process differs from the fusion draw process. In the slot draw process, molten raw glass is provided to a drawing tank. The bottom of the drawing tank has an open slot with a nozzle extending the length of the slot. The molten glass flows through the slot / nozzle and is drawn downward as a continuous glass-based article to an annealing zone. If the glass-based article is a glass-ceramic, the glass-based article formed by the slot draw process may be subjected to a ceramming process whereby one or more crystalline phases are produced.

[0136] In some embodiments, the glass-based article may be formed using thin-rolling methods, such as those described in U.S. Pat. No. 8,713,972, entitled "Precision Glass Roll Forming Process and Apparatus," U.S. Pat. No. 9,003,835, entitled "Precision Roll Forming of Textured Sheet Glass," U.S. Patent Application Publication No. 2015 / 0027169, entitled "Methods And Apparatus For Forming A Glass Ribbon," and U.S. Patent Application Publication No. 2005 / 0099618, entitled "Apparatus and Method for Forming Thin Glass Articles," the contents of which are incorporated herein by reference in their entireties. More particularly, the glass-based article is formed by providing a vertical stream of molten glass, forming the provided stream of molten glass or glass ceramic with a pair of forming rolls maintained at a surface temperature of about 500°C or greater, or about 600°C or greater, to form a formed glass ribbon having a formed thickness, and sizing the formed glass ribbon with a pair of sizing rolls maintained at a surface temperature of about 400°C or less to produce a sized glass ribbon having a desired thickness less than the formed thickness and a desired thickness uniformity.The apparatus used to form the glass ribbon may include a glass feeder for feeding a supply stream of molten glass; a pair of forming rolls maintained at a surface temperature of about 500°C or greater, the forming rolls being closely spaced adjacent to each other defining a glass forming nip between the forming rolls, the glass forming nip being positioned vertically below the glass feeder for receiving the supply stream of molten glass and thinning the supply stream of molten glass between the forming rolls to form a formed glass ribbon having a formed thickness; and a pair of sizing rolls maintained at a surface temperature of about 400°C or less, the sizing rolls being closely spaced adjacent to each other defining a glass sizing nip between the sizing rolls, the glass sizing nip being positioned vertically below the forming rolls for receiving the formed glass ribbon and thinning the formed glass ribbon to produce a sized gapped glass ribbon having a desired thickness and a desired thickness uniformity.

[0137] In some cases, thin-rolling may be utilized when the viscosity of the glass precludes the use of fusion or slot-draw processes. For example, thin-rolling can be utilized to form glass-based articles when the glass exhibits a liquidus viscosity of less than 100 kP.

[0138] The glass-based article may be acid polished or otherwise treated to eliminate or reduce the effects of surface scratches.

[0139] Another aspect of the present disclosure relates to a method of forming a fracture-resistant glass-based article, the method comprising providing a glass-based substrate having a first surface and a second surface, the glass-based substrate defining a thickness of about 1 millimeter or less, and creating a stress profile in the glass-based substrate as described herein to provide the fracture-resistant glass-based article. In one or more embodiments, creating the stress profile comprises ion-exchanging a plurality of alkali ions into the glass-based substrate to form a non-zero alkali metal oxide concentration that varies along a substantial portion of the thickness (as described herein) or along the entire thickness. In one example, creating the stress profile comprises ion-exchanging a plurality of alkali ions into the glass-based substrate at a temperature of about 350°C or greater (e.g., from about 350°C to about 500°C). + , K. + , Rb + , Cs + or a combination thereof. In one example, the molten salt bath may include NaNO3 and have a temperature of about 485° C. In another example, the bath may include NaNO3 and have a temperature of about 430° C. The glass-based substrate may be immersed in the bath for at least about 2 hours, up to about 48 hours (e.g., about 12 hours to about 48 hours, about 12 hours to about 32 hours, about 16 hours to about 32 hours, about 16 hours to about 24 hours, or about 24 hours to about 32 hours).

[0140] In some embodiments, the method may include chemically strengthening or ion-exchanging a glass-based substrate in multiple steps using sequential immersion steps in multiple baths. For example, two or more baths may be used in series. The compositions of the two or more baths may be different from each other, with the same bath containing only a single metal (e.g., Ag). + , Na + , K. + , Rb + , or Cs +) or a combination of metals. When multiple baths are used, the baths may have the same or different compositions and / or temperatures. The immersion time in each such bath may be the same or different to impart the desired stress profile.

[0141] In one or more embodiments, a second or subsequent bath may be utilized to create a larger surface Cs. In some cases, the method includes immersing the glass-based substrate in the second or subsequent bath to create a larger surface Cs without significantly affecting the chemical depth and / or DOC of the layer. In such embodiments, the second or subsequent bath may include a single metal (e.g., KNO or NaNO) or a mixture of metals (e.g., KNO and NaNO). The temperature of the second or subsequent bath may be adjusted to create the larger surface Cs. In some embodiments, the immersion time of the glass-based substrate in the second or subsequent bath may also be adjusted to create a larger surface Cs without affecting the chemical depth and / or DOC of the layer. For example, the immersion time in the second or subsequent bath may be less than 10 hours (e.g., about 8 hours or less, about 5 hours or less, about 4 hours or less, about 2 hours or less, about 1 hour or less, about 30 minutes or less, about 15 minutes or less, or about 10 minutes or less).

[0142] In one or more alternative embodiments, the method may include one or more heat treatment steps that can be used in combination with the ion exchange steps described herein. The heat treatment includes heat treating the glass-based article to achieve a desired stress profile. In some embodiments, the heat treatment step includes annealing, heat strengthening, or heating the glass-based substrate to a temperature ranging from about 300°C to about 600°C. The heat treatment may last from 1 minute to about 18 hours. In some embodiments, the heat treatment may be used after or during one or more ion exchange steps. [Example]

[0143] The following examples further clarify various embodiments. In the examples, the examples are referred to as "substrates" before being tempered. The examples are referred to as "articles" or "glass-based articles" after being tempered.

[0144] Example 1 Glass-ceramic substrates were provided having the nominal compositions shown in Table 2 below. The glass-ceramic substrates were 0.8 mm thick and contained a β-spodumene solid solution as a predominant crystalline phase and a crystalline phase assemblage including one or more minor phases including rutile. The glass-ceramic substrates were immersed in a molten salt bath containing NaNO having a temperature of 485°C for 10 hours (Condition A), 13 hours (Condition B), or 24 hours (Condition C), or in a molten salt bath containing NaNO having a temperature of 430°C for 2 hours (Comparative Condition D) to form glass-ceramic articles.

[0145] [Table 2]

[0146] The stress profile of the glass-ceramic article was measured by microprobe and is shown in Figure 5. As shown in Figure 5, Na + Ions are exchanged throughout nearly the entire thickness of the article when a higher temperature bath is utilized (i.e., conditions A-C). In such glass-ceramics, NaO is present in the CT region in an amount of about 1.2 mol % or greater. Glass-ceramic articles ion-exchanged in a lower temperature bath (comparative condition D) exhibited stress profiles similar to known stress profiles.

[0147] Example 2 Glass substrates having the same composition and 0.8 mm thickness as shown in Table 2, but with an amorphous structure (no crystalline phase), were chemically strengthened by immersion in a molten salt bath containing 100% NaNO at a temperature of approximately 430°C for various periods to provide glass articles. The DOC and maximum CT of the glass articles were measured using a scattered light polarimeter (SCALP). As shown in Figure 6, the DOC and maximum CT increase with increasing immersion, i.e., ion exchange, length. The maximum CT value was observed after the glass was immersed for approximately 16 hours.

[0148] The stress profile of the glass article of Example 2 was measured using SCALP. The stress profile is shown in Figure 7. The upper portion of the x-axis, which represents positive stress values, is the CT layer, and the lower portion of the x-axis, which represents negative stress values, is the CS value. The stress profile of the glass article chemically strengthened for 16 hours exhibited a maximum CT value (i.e., 175 MPa) and a parabolic shape in the depth direction of 100 micrometers, substantially free of linear portions. The surface CS measured by SCALP was about 410 MPa. Therefore, the ratio of maximum CT to surface CS for Example 2 is about 0.4375.

[0149] Example 3 For comparison, the glass-ceramic substrate of Example 1 and the glass substrate of Example 2, each having a thickness of about 0.8 mm, were chemically strengthened by immersion in a molten salt bath of NaNO having a temperature of 350°C for 3.5 hours (Examples 3A and 3B, respectively). The resulting stress profiles of the glass-ceramic and glass articles shown in Figure 8 resemble an error function (erfc) or quasi-linear shape. Furthermore, the CS depth of the layer is smaller than the depth of alkali ions exchanged into the glass or glass-ceramic (or chemical ion exchange depth).

[0150] When the glass-ceramic substrate of Example 1 and the glass substrate of Example 2, each having a thickness of about 0.8 mm, were subjected to the chemical strengthening described herein by immersion in a molten salt bath of NaNO having a temperature of 430° C. for 24 hours (Examples 3C and 3D, respectively), the resulting glass-based articles exhibited a metal oxide concentration profile (obtained by EPMA) as shown in Figure 9. The metal oxide concentration profile was parabolic, with Na throughout the entire thickness. + The ion exchange of ions is shown. The chemical profile was measured using EMPA. The chemical depth of NaO diffusion is shown to be greater than 400 micrometers. Furthermore, NaO is present at a concentration of greater than about 1 mol % throughout the thickness, including the CT layer. The resulting glass-ceramic article of Example 3D exhibited excellent fracture resistance in a drop test in which the glass-ceramic substrate was mounted in the housing of an identical mobile phone. Specifically, five samples of Example 3D were incorporated into a mobile phone device and dropped onto abrasive paper for successive drops starting at a depth of 50 cm. As each sample survived a drop from a certain height, the sample was again dropped from increasing heights until cracking occurred. At that point, the failure height of the sample was recorded in Figure 9A. Example 3D exhibited an average failure height of 172.5 cm.

[0151] Figure 10 shows stress profiles for glass-based substrates chemically strengthened by known processes and glass-based substrates chemically strengthened according to the methods described herein. As shown in Figure 10, the stress profile of the glass-based article of the embodiments described herein has a shape that is substantially free of linear segments (having a length or absolute depth greater than about 50 micrometers) and exhibits a DOC of about 0.2 t, while the known stress profile exhibits a substantially linear portion from a depth of about 0.1 millimeter to about 0.7 millimeters (a total length of about 0.6 millimeters or 600 micrometers). The known stress profile also exhibits a lower CT value and a smaller DOC.

[0152] Example 4 Glass substrates (each approximately 1 mm thick) having the compositions shown in Table 2 were chemically strengthened by immersion in a first molten salt bath of NaNO3 at a temperature of 430°C for 24 hours. One glass-based article was not subjected to any additional strengthening step (Example 4A). Three glass-based articles were subjected to a second strengthening step by immersion in a second molten salt bath of KNO3 at a temperature of 430°C for either 0.75 hours, 4 hours, or 8 hours (Examples 4B, 4C, and 4D, respectively). Stress profiles measured by SCALP for the resulting glass-based articles are shown in Figure 11. The depth or thickness of the glass-based article is plotted on the x-axis, and stress is plotted on the y-axis. Positive stress values ​​are CT values, and negative stress values ​​are CS values. The spatial resolution of the instrument prevented measurement of CS, which is related to the second KNO3 ion-exchange step. The glass-based articles of Examples 4A and 4B exhibited similar profiles. The glass-based articles of Examples 4C and 4D exhibited a decreased CT (compared to Examples 4A and 4B) and a decreased CS (compared to Examples 4A and 4B) over time after immersion in the second tempering step. The glass-based articles of Examples 4C and 4D also exhibited an increased DOC compared to Examples 4A and 4B, such DOC values ​​being greater than 0.2 t.

[0153] FIG. 12 shows the J / m for each of Examples 4B to 4D. 2 The stored tensile energy, expressed in mJ / m, varies depending on the time of immersion in the second molten salt bath of KNO3. 2 The stored tensile energy can be calculated from the measured SCALP stress profile data using equation (3) above.

[0154] Figures 13 and 14 show the concentration profiles of each of KO and NaO as a function of depth (micrometers) for each of Examples 4B-4D. As shown in Figure 13, the chemical depth of KO is 3 micrometers (Example 4B, 0.75 hour immersion in a KNO bath), 6 micrometers (Example 4C, 4 hour immersion in a KNO bath), and 5 micrometers (Example 4D, 8 hour immersion in a KNO bath). As shown in Figure 14, NaO penetrates the entire depth and has a concentration of about 1 mol % or greater along the entire depth of the glass-based article for each of Examples 4B-4D.

[0155] Examples 4E and 4F included glass substrates (each approximately 1 mm thick) having the compositions in Table 2. The substrates were chemically strengthened by immersion in a first molten salt bath of NaNO having a temperature of 430°C for 24 hours, followed by heat treatment in air at a temperature of 430°C for 4 hours or 8.25 hours, respectively. The stress profiles for the glass-based articles of Examples 4E and 4F are shown in Figure 15, with stress profiles for Examples 4A, 4C, and 4D shown for comparison. Figure 16 shows the same graph as Figure 15, but on a smaller scale to illustrate the difference in stress profiles at or near a depth of 0.5 t.

[0156] Example 5 Glass substrates (each approximately 1 mm thick) having the compositions shown in Table 2 were chemically strengthened by immersion in a first molten salt bath of NaNO3 at a temperature of 430°C for 24 hours. One glass-based article was not subjected to any additional strengthening step (Example 5A). Two glass-based articles were subjected to a second strengthening step by placing the glass-based articles in a furnace at 390°C and maintaining the glass-based articles in the furnace for either 8 or 28 hours (Examples 5B-5C, respectively). Four glass-based articles were subjected to a third strengthening step (after either the first strengthening step or a different second strengthening step) by immersion in a second molten salt bath of KNO3 at a temperature of 430°C for either 4 or 8 hours (Examples 5D-5G). The strengthening steps for each of Examples 5A-5G are shown in Table 3. The measured CT values ​​are also shown in Table 3.

[0157] [Table 3]

[0158] The resulting stress profile of the glass-based article is shown in Figure 17. The depth or thickness of the glass-based article is plotted on the x-axis, and stress is plotted on the y-axis. Positive stress values ​​are CT values, and negative stress values ​​are CS values. As shown in Figure 17, as the duration of the second and / or third heat treatments increased, the DOC increased and the CT decreased. The decrease in DOC and CT is more clearly shown in Figures 18 and 19, respectively.

[0159] The glass-based articles of Examples 5A-5G were then subjected to a poke test in which tape was applied to one side of the glass-based article and a sharp instrument was struck against the opposite bare side to break it. The number of resulting fragments can be correlated to the stored tensile energy of the glass-based article. Examples 5A, 5B, and 5D exhibited a large number of fragments (i.e., over 50 and even 100), while Example 5F exhibited 10 fragments, Example 5C exhibited 3 fragments, and Examples 5E and 5G exhibited 4 fragments. Examples 5A, 5B, and 5D, which exhibited a large number of fragments, exhibited higher CTs (greater than about 100 MPa) than Examples 5C, 5E, 5F, and 5G, which all had CT values ​​of about 100 MPa or less.

[0160] Example 6 Glass substrates with a nominal composition of 57.5 mol% SiO, 16.5 mol% AlO, 16.7 mol% NaO, 2.5 mol% MgO, and 6.5 mol% PO and thicknesses of approximately 0.4 mm, 0.55 mm, or 1 mm were chemically strengthened. The thicknesses and chemical strengthening conditions are shown in Table 4.

[0161] [Table 4]

[0162] Example 6A was immersed in a molten salt bath as shown in Table 4 for 4, 8, 16, 32, 64, and 128 hours (Examples 6A-1 to 6A-6). Example 6B was immersed in a molten salt bath as shown in Table 4 for 4, 8, 16, 32, 64, and 128 hours (Examples 6B-1 to 6B-6). Example 6C was immersed in a molten salt bath as shown in Table 4 for 1, 2, 4, 8, 16, and 32 hours (Examples 6C-1 to 6C-6). Example 6D was immersed in a molten salt bath as shown in Table 4 for 4, 8, 16, 32, 64, and 128 hours (Examples 6D-1 to 6D-6). The stress profiles for Examples 6A-1 through 6A-6, 6B-1 through 6B-6, 6C-1 through 6C-6, and 6D-1 through 6D-6 are shown in Figures 20, 22, 24, and 26, respectively. In Figures 20, 22, 24, and 26, the depth or thickness of the glass article is plotted on the x-axis and stress is plotted on the y-axis. Positive stress values ​​are CT values ​​and negative stress values ​​are CS values.

[0163] The CT and DOC values ​​as a function of time immersed in the molten salt bath for Examples 6A-1 to 6A-6, Examples 6B-1 to 6B-6, Examples 6C-1 to 6C-6, and Examples 6D-1 to 6D-6 are shown in Figures 21, 23, 25, and 27, respectively.

[0164] Example 7 Glass substrates having a nominal composition as shown in Table 2 and a thickness of approximately 1 mm were chemically strengthened in a molten salt bath containing 100% NaNO at a temperature of 430° C. The duration of immersion of the glass substrates in the molten salt bath is shown in Table 5.

[0165] [Table 5]

[0166] The stress profiles of the glass-based articles of Examples 7A-7G are shown in Figure 28. These stress profiles were measured using SCALP. As shown in Figure 28, immersion of the glass substrates in the molten salt bath for 16 and 24 hours results in glass-based articles that exhibit the highest surface Cs and Ct values, in absolute terms. Graphs showing the change in Ct value and stored tensile energy, both as a function of ion-exchange time, are shown in Figure 29.

[0167] Example 8 Glass substrates having the nominal compositions shown in Table 2 and each having a thickness of approximately 0.8 mm were chemically strengthened in a molten salt bath containing a mixture of NaNO3 and NaSO4 at a temperature of 500°C for 15 minutes (Comparative Example 8A) and 16 hours (Example 8B). The stress profiles of the glass-based articles of Examples 8A and 8B are shown in Figure 30. As shown in Figure 30, Comparative Example 8A exhibited a known stress profile, while Example 8B exhibited a stress profile according to one or more of the present disclosures. The stored tensile energy of the glass-based articles of Examples 8A and 8B was calculated in the same manner as Examples 4B-4D. The calculated stored tensile energy is plotted as a function of the measured CT (MPa), as shown in Figure 31.

[0168] As shown in Figure 31, Comparative Example 8A exhibited a much higher stored tensile energy value for a given CT value than Example 8B (for the same CT value). Specifically, at a CT of about 55 MPa, Comparative Example 8A exhibited a stored tensile energy value of about 8 J / m 2 The stored tensile energy of the example was about 3.5 J / m 2 Comparative Example 8A and Example 8B cracked, with Example 8B cracking into fewer pieces than Comparative Example 8A. Comparative Example 8A cracked into a much larger number of pieces. Therefore, without being bound by theory, it is believed that controlling the stored tensile energy may provide a way to control or predict the cracking pattern or the number of pieces resulting from the crack.

[0169] Glass substrates having the nominal compositions shown in Table 2 and each having a thickness of approximately 1 mm were chemically strengthened in a molten salt bath containing NaNO at a temperature of 430°C for 4 hours (Comparative Example 8C) and 61.5 hours (Example 8D). Comparative Example 8C exhibited a known stress profile, while Example 8D exhibited a stress profile according to one or more of the present disclosures. The stored tensile energy of Examples 8C and 8D was calculated using the same method used for Examples 4B-4D and plotted as a function of the measured CT (MPa), as shown in Figure 32.

[0170] As shown in Figure 32, Comparative Example 8C exhibited a much higher stored tensile energy value for a given CT value than Example 8D (for the same CT value). Comparative Example 8C and Example 8D cracked, with Example 8D cracking into fewer pieces than Comparative Example 8C. Comparative Example 8C cracked into a much larger number of pieces.

[0171] Example 9 A glass substrate having a nominal composition of 70.9 mol% SiO, 12.8 mol% AlO, 1.95 mol% BO, 7.95 mol% LiO, 2.43 mol% NaO, 2.98 mol% MgO, 0.89 mol% ZnO, and 0.1 mol% SnO and a thickness of approximately 0.8 mm was subjected to the ion exchange conditions in Table 6. Various properties of Example 9 are compared to Example 2 in Table 7.

[0172] [Table 6]

[0173] [Table 7]

[0174] The stress profiles were measured for the glass-based articles of Example 9. These stress profiles exhibited the shapes described herein.

[0175] Glass substrates according to Examples 2, 6, and Comparative Example 9A were provided having the same thickness as Example 9. The glass substrate according to Example 2 was ion-exchanged in a molten bath of 100% NaNO having a temperature of 430°C for 33 hours. The glass substrate according to Example 6 was ion-exchanged and exhibited the known error function stress profile. Comparative Example 9A was ion-exchanged in a molten bath of 100% NaNO having a temperature of 390°C for 16 hours, and also exhibited the known error function stress profile. As used herein, the term "error function stress profile" refers to a stress profile similar to that of FIG. 1.

[0176] The glass-based articles from Examples 2, 6, 9, and Comparative Example 9A were then mounted on identical mobile phone devices. These phone devices were dropped onto 30-grit sandpaper from incremental heights starting at 20 centimeters. If the glass-based article survived a drop from a certain height (e.g., 20 cm), the mobile phone was dropped again from a higher height (e.g., 30 cm, 40 cm, 50 cm, etc.). The heights at which the glass-based articles broke are plotted in FIG. 33, which also shows the average breakage heights for the samples of Examples 2, 6, and 9, as well as Comparative Example 9A. As shown in FIG. 33, Examples 2 and 9 broke at significantly higher drop heights than Example 6 and Comparative Example 9A. Specifically, Example 6 and Comparative Example 9A broke at drop heights of approximately 38 cm and 55 cm, respectively, while Examples 2 and 9 broke at drop heights of approximately 147 cm and 132 cm, respectively.

[0177] The same test was repeated on new samples using the same mobile phone device on 180 grit sandpaper. The average break height for Example 6 was 190 cm, for Comparative Example 9A it was 204 cm, for Example 2 it was 214 cm, and for Example 9 it was 214 cm.

[0178] Ion-exchanged glass substrates according to Comparative Example 9B, having a nominal composition of 65 mol% SiO, 5 mol% BO, 14 mol% AlO, 14 mol% NaO, 2 mol% MgO, and 0.1 mol% SnO, and a thickness of 0.8 mm, exhibited known error function stress profiles. Samples of the glass-based articles of Examples 2 and 6 (which exhibit the stress profiles described above in this example), Comparative Example 9B, and the glass-based article of Example 9 ion-exchanged according to Condition 4 as shown in Table 5, were subjected to A-ROR testing, as described herein.

[0179] Examples 6 and 9, and Comparative Example 9B, were polished using loads or pressures of 25 psi (about 172 kPa) and 45 psi (about 310 kPa), while Example 2 was polished using only a 25 psi (about 172 kPa) load. The AROR data is shown in Figure 34. As shown in Figure 34, Examples 2 and 9 exhibited higher failure loads than Example 6 and Comparative Example 9B.

[0180] Samples of the glass-based articles of Examples 2 (ion-exchanged as described above in this Example) and 9 (ion-exchanged according to Condition 4) were subjected to four-point bend tests, the results of which are shown in the Weibull distribution plot of Figure 35. As shown in Figure 35, Example 9 exhibited a higher failure load or stress (e.g., greater than about 400 MPa).

[0181] As previously indicated, glass-based articles made from compositions having strain points greater than 525°C allow for ion exchange temperatures (or ion exchange bath temperatures) ranging from about 350°C to about 480°C. In some embodiments, glass compositions exhibiting a diffusivity greater than about 800 square millimeters per hour allow metal oxides to diffuse into the glass-based article and penetrate the entire depth or thickness of the article so rapidly that stress relaxation is minimized. Excessive stress relaxation can reduce the surface compressive stress of the glass-based article.

[0182] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention.

[0183] Preferred embodiments of the present invention will be described below in detail.

[0184] Embodiment 1 In glass-based articles, a first surface and a second surface opposite the first surface, the second surface defining a thickness (t); a concentration of metal oxide that is non-zero and varies along a thickness range of about 0·t to about 0.3·t; and If the glass-based article breaks, the glass-based article will break into pieces of 1 square inch (approximately 6.4516 cm 2 ) glass-based articles that break into at least 2 pieces per impact.

[0185] Embodiment 2 2. The glass-based article of claim 1, wherein the concentration of the metal oxide is non-zero and varies along the entire thickness.

[0186] Embodiment 3 3. The glass-based article of claim 1 or 2, wherein the metal oxide creates stress along the thickness range.

[0187] Embodiment 4 4. The glass-based article of any one of claims 1 to 3, wherein a concentration of the metal oxide decreases from the first surface to a point between the first surface and the second surface, and increases from that point to the second surface.

[0188] Embodiment 5 5. The glass-based article of any one of embodiments 1 to 4, further having a surface compressive stress (CS) of about 300 MPa or greater.

[0189] Embodiment 6 6. The glass-based article of claim 5, wherein the surface CS is about 600 MPa or greater.

[0190] Embodiment 7 7. The glass-based article of any one of claims 1 to 6, wherein the concentration of the metal oxide is greater than or equal to about 0.05 mol% throughout the thickness.

[0191] Embodiment 8 8. The glass-based article of any one of claims 1 to 7, wherein the concentration of the metal oxide at the first surface is about 1.5 times greater than the concentration of the metal oxide at a depth equal to about 0.5 t.

[0192] Embodiment 9 9. The glass-based article of any one of claims 1 to 8, wherein the glass-based article has a total concentration of the metal oxides ranging from about 1 mol% to about 15 mol%.

[0193] Embodiment 10 10. The glass-based article of any one of claims 1 to 9, wherein the metal oxide comprises any one or more of Li2O, Na2O, KO, Rb2O, and Cs2O.

[0194] Embodiment 11 11. The glass-based article of any one of claims 1 to 10, further having a surface C S of about 300 MPa or greater and a chemical depth of layer of about 0.4·t or greater.

[0195] Embodiment 12 12. The glass-based article of any one of the preceding claims, further comprising a CS layer extending from the first surface to a DOC that is about 0.1 t or greater.

[0196] Embodiment 13 13. The glass-based article of any one of claims 1 to 12, further comprising a central tension (CT) region, the CT region comprising a concentration gradient of said metal oxide.

[0197] Embodiment 14 14. The glass-based article of claim 13, wherein the CT region has a maximum CT, and the ratio of maximum CT to surface CS ranges from about 0.01 to about 0.5.

[0198] Embodiment 15 15. The glass-based article of any one of claims 1 to 14, wherein t comprises about 3 millimeters or less.

[0199] Embodiment 16 16. The glass-based article of any one of claims 1 to 15, wherein t comprises about 1 millimeter or less.

[0200] Embodiment 17 17. The glass-based article of any one of claims 1 to 16, further having an amorphous structure.

[0201] Embodiment 18 18. The glass-based article of any one of the preceding claims, further having a crystalline structure.

[0202] Embodiment 19 19. The glass-based article of any one of claims 1 to 18, further exhibiting a transmittance of about 88% or greater over a wavelength range from about 380 nm to about 780 nm.

[0203] Embodiment 20 20. The glass-based article of any one of claims 1 to 19, further exhibiting a transmittance of less than or equal to about 10% over a wavelength range from about 380 nm to about 780 nm.

[0204] Embodiment 21 Under CIE illuminant F02, approximately 88 L or more * Values, a range from about -3 to about +3 * values, and b in the range of about -6 to about +6 * 21. The glass-based article of any one of the preceding claims, further showing CIELAB color space coordinates of:

[0205] Embodiment 22 Under CIE illuminant F02, approximately 40 L or less * Values, a range from about -3 to about +3 * values, and b in the range of about -6 to about +6 * 22. The glass-based article of any one of the preceding claims, further showing CIELAB color space coordinates of:

[0206] Embodiment 23 a first surface and a second surface opposite the first surface, a first metal oxide concentration, and a second metal oxide concentration, the first surface and the second metal oxide concentration defining a thickness (t); and the first metal oxide concentration is in the range of about 0 mol % to about 15 mol % along a first thickness range of about 0·t to about 0.5·t; 23. The glass-based article of any one of the preceding claims, wherein the second metal oxide concentration ranges from about 0 mol% to about 10 mol% along a second thickness range of about 0 micrometers to about 25 micrometers.

[0207] Embodiment 24 24. The glass-based article of embodiment 23, further comprising a third metal oxide.

[0208] Embodiment 25 In glass-based articles, a first surface and a second surface opposite the first surface, the first surface defining a thickness (t) of less than about 3 millimeters; and a stress profile extending through the thickness; and all points of the stress profile between thickness ranges of about 0·t to 0.3·t and greater than 0.7·t have a tangent less than about −0.1 MPa / micrometer or greater than about 0.1 MPa / micrometer; the stress profile has a maximum CS, a DOC, and a maximum CT, the ratio of maximum CT to maximum CS being in the range of about 0.01 to about 0.5, and the DOC being greater than or equal to about 0.1 t; If the glass-based article breaks, the glass-based article will break into pieces of 1 square inch (approximately 6.4516 cm 2 ) glass-based articles that break into at least 2 pieces per impact.

[0209] Embodiment 26 26. The glass-based article of embodiment 25, further having a surface CS of about 300 MPa or greater.

[0210] Embodiment 27 27. The glass-based article of claim 26, wherein the surface CS is about 600 MPa or greater.

[0211] Embodiment 28 28. The glass-based article of any one of claims 25 to 27, further having a surface CS of about 300 MPa or greater and a chemical depth of layer (DOL) of about 0.4·t or greater.

[0212] Embodiment 29 29. The glass-based article of any one of claims 25 to 28, further comprising a CS layer extending from the first surface to a DOC that is about 0.1 t or greater.

[0213] Embodiment 30 30. The glass-based article of any one of claims 25 to 29, further comprising a CT region, the CT region comprising a concentration gradient of a metal oxide.

[0214] Embodiment 31 31. The glass-based article of claim 30, wherein the CT region has a maximum CT, and the ratio of maximum CT to surface CS is in the range of about 0.01 to about 0.5.

[0215] Embodiment 32 32. The glass-based article of any one of claims 25 to 31, wherein t comprises about 2 millimeters or less.

[0216] Embodiment 33 33. The glass-based article of any one of claims 25 to 32, wherein t comprises about 1 millimeter or less.

[0217] Embodiment 34 In glass-based articles, a first surface and a second surface opposite the first surface, the first surface defining a thickness (t); a concentration of metal oxide that is non-zero and varies along a thickness range of about 0·t to about 0.3·t; and Surface CS of approximately 200 MPa or more, A glass-based article having:

[0218] Embodiment 35 35. The glass-based article of claim 34, wherein the thickness range is from about 0·t to about 0.4t.

[0219] Embodiment 36 36. The glass-based article of claim 34 or 35, wherein the thickness range is from about 0·t to about 0.45t.

[0220] Embodiment 37 37. The glass-based article of any one of claims 34 to 36, wherein the metal oxide creates stress along the thickness range.

[0221] Embodiment 38 38. The glass-based article of claim 37, wherein the metal oxide has the largest ionic diameter of all of the metal oxides in the glass-based article.

[0222] Embodiment 39 39. The glass-based article of any one of claims 34 to 38, wherein the concentration of the metal oxide decreases from the first surface to a point between the first surface and the second surface, and increases from that point to the second surface.

[0223] Embodiment 40 If the glass-based article breaks, the glass-based article will break into pieces of 1 square inch (approximately 6.4516 cm 2 At least 1 fragment per square inch (approximately 6.45 cm 2 40. The glass-based article of any one of claims 34 to 39, which breaks into up to 40 pieces per sieve.

[0224] Embodiment 41 The glass-based article has a thickness of about 450 μm at about 460° C. 2 41. The glass-based article of any one of claims 34 to 40, having a diffusivity of at least 1 / hr, a maximum CT, and a DOC of greater than about 0.15 t, and wherein the surface CS is at least 1.5 times the maximum CT.

[0225] Embodiment 42 The glass-based article has a viscosity of about 0.7 MPa m 1 / 2 Fracture toughness (K 1C 42. The glass-based article of any one of claims 34 to 41, wherein

[0226] Embodiment 43 42. The glass-based article of claim 41, wherein the surface CS is greater than the maximum CT.

[0227] EMBODIMENT 44 44. The glass-based article of any one of claims 34 to 43, wherein the surface C S is about 300 MPa or greater.

[0228] Embodiment 45 45. The glass-based article of any one of claims 34 to 44, wherein the surface C S is about 600 MPa or greater.

[0229] Embodiment 46 46. ​​The glass-based article of any one of claims 34 to 45, wherein the concentration of the metal oxide is greater than or equal to about 0.05 mol% throughout the thickness.

[0230] Embodiment 47 47. The glass-based article of any one of claims 34 to 46, wherein the concentration of the metal oxide at the first surface is about 1.5 times greater than the concentration of the metal oxide at a depth equal to about 0.5 t.

[0231] Embodiment 48 48. The glass-based article of any one of claims 34 to 47, wherein the total concentration of metal oxides ranges from about 1 mol% to about 15 mol%.

[0232] Embodiment 49 49. The glass-based article of any one of claims 34 to 48, wherein the metal oxide comprises any one or more of Li2O, Na2O, KO, Rb2O, and Cs2O.

[0233] Embodiment 50 50. The glass-based article of any one of claims 34 to 49, further having a chemical depth of layer of about 0.4·t or greater.

[0234] Embodiment 51 51. The glass-based article of any one of claims 34 to 50, further comprising a CS layer extending from the first surface to a DOC that is about 0.1 t or greater.

[0235] Embodiment 52 52. The glass-based article of any one of claims 34 to 51, further comprising a CT region, the CT region comprising a concentration gradient of said metal oxide.

[0236] Embodiment 53 53. The glass-based article of claim 52, wherein the CT region has a maximum CT, and the ratio of maximum CT to surface CS is in the range of about 0.01 to about 0.5.

[0237] EMBODIMENT 54 54. The glass-based article of any one of claims 34 to 53, wherein t comprises about 3 millimeters or less.

[0238] Embodiment 55 55. The glass-based article of any one of claims 34 to 54, wherein t comprises about 1 millimeter or less.

[0239] Embodiment 56 In glass-based articles, a first surface and a second surface opposite the first surface, the second surface defining a thickness (t); Metal oxides that form concentration gradients, and a concentration of the metal oxide decreases from the first surface to a point between the first surface and the second surface and increases from that point to the second surface; the concentration of the metal oxide at the point is not zero, The glass-based article has a viscosity of about 0 J / m 2 Over 20J / m 2 1. A glass-based article exhibiting a stored tensile energy of less than 1000 kJ / cm.

[0240] Embodiment 57 57. The glass-based article of embodiment 56, further having a surface CS of about 300 MPa or greater.

[0241] Embodiment 58 58. The glass-based article of claim 57, wherein the surface CS is about 600 MPa or greater.

[0242] Embodiment 59 59. The glass-based article of any one of claims 56 to 58, wherein the concentration of the metal oxide is greater than or equal to about 0.05 mol% throughout the thickness.

[0243] Embodiment 60 60. The glass-based article of any one of claims 56 to 59, wherein the concentration of the metal oxide at the first surface is about 1.5 times greater than the concentration of the metal oxide at a depth equal to about 0.5 t.

[0244] Embodiment 61 61. The glass-based article of any one of claims 56 to 60, wherein the total concentration of metal oxides ranges from about 1 mol% to about 15 mol%.

[0245] Embodiment 62 62. The glass-based article of any one of claims 56 to 61, wherein the metal oxide comprises any one or more of Li2O, Na2O, KO, Rb2O, and Cs2O.

[0246] Embodiment 63 63. The glass-based article of any one of embodiments 56 to 62, further having a surface Cs of about 200 MPa or greater and a chemical depth of layer of about 0.4·t or greater.

[0247] EMBODIMENT 64 64. The glass-based article of any one of claims 56 to 63, further comprising a CS layer extending from the first surface to a DOC that is about 0.1 t or greater.

[0248] Embodiment 65 65. The glass-based article of any one of claims 56 to 64, further comprising a CT region, the CT region comprising a concentration gradient of said metal oxide.

[0249] Embodiment 66 66. The glass-based article of claim 65, wherein the CT region has a maximum CT, and the ratio of maximum CT to surface CS is in the range of about 0.01 to about 0.5.

[0250] Embodiment 67 67. The glass-based article of any one of embodiments 56 to 66, wherein t comprises about 3 millimeters or less.

[0251] Embodiment 68 68. The glass-based article of any one of embodiments 56 to 67, wherein t comprises about 1 millimeter or less.

[0252] Embodiment 69 In glass-based articles, a first surface and a second surface opposite the first surface, the first surface defining a thickness (t) of less than about 3 millimeters; and a stress profile extending through the thickness; and all points of the stress profile between thickness ranges of about 0·t to 0.3·t and greater than 0.7·t have a tangent less than about −0.1 MPa / micrometer or greater than about 0.1 MPa / micrometer; the stress profile has a maximum CS, a DOC, and a maximum CT, the ratio of maximum CT to maximum CS being in the range of about 0.01 to about 0.5, and the DOC being greater than or equal to about 0.1 t; The glass-based article has a viscosity of about 0 J / m 2 Over 20J / m 2 1. A glass-based article exhibiting a stored tensile energy of less than 1000 kJ / cm.

[0253] Embodiment 70 70. The glass-based article of embodiment 69, further comprising a continuously varying, non-zero concentration of metal oxide along its entire thickness.

[0254] Embodiment 71 71. The glass-based article of embodiment 69 or 70, further having a non-zero concentration of metal oxide that varies continuously along a thickness segment of less than about 10 micrometers.

[0255] Embodiment 72 72. The glass-based article of any one of claims 69 to 71, wherein the maximum CS comprises about 300 MPa or greater.

[0256] Embodiment 73 73. The glass-based article of any one of claims 69 to 72, wherein the maximum CS comprises about 600 MPa or greater.

[0257] EMBODIMENT 74 74. The glass-based article of any one of embodiments 69 to 73, further having a chemical depth of layer of about 0.4·t or greater.

[0258] Embodiment 75 75. The glass-based article of any one of claims 69 to 74, further comprising a CT region, the CT region comprising a concentration gradient of said metal oxide.

[0259] Embodiment 76 76. The glass-based article of any one of embodiments 69 to 75, wherein t comprises about 3 millimeters or less.

[0260] Embodiment 77 77. The glass-based article of any one of embodiments 69 to 76, wherein t comprises about 1 millimeter or less.

[0261] Embodiment 78 In glass-based articles, stress profile including CS and CT regions, and The CT region has the formula:

[0262]

number

[0263] is defined by wherein MaxCT is the maximum CT value given as a positive value in units of MPa, x is the position along the thickness (t) in micrometers, and n is between 1.5 and 5.

[0264] Embodiment 79 79. The glass-based article of claim 78, wherein the CT region has a maximum CT value in the range of about 50 MPa to about 250 MPa, and the maximum CT value is at a depth in the range of about 0.4t to about 0.6t.

[0265] Embodiment 80 80. The glass-based article of claim 78 or 79, wherein the stress profile has a gradient in the range of about 20 MPa / micrometer to about 200 MPa / micrometer over a thickness in the range of about 0t to about 0.1t.

[0266] Embodiment 81 81. The glass-based article of any one of claims 78-80, wherein the stress profile is defined by a plurality of error functions, measured from 0.5t to the surface.

[0267] Embodiment 82 1. A method of forming a fracture-resistant glass-based article, comprising: providing a glass-based substrate having a first surface and a second surface, the first surface defining a thickness of about 3 millimeters or less; generating a stress profile in the glass-based substrate having a CT layer and a CS layer, the CS layer having a surface CS, a chemical depth of about 0.4t or greater, and a DOC of about 0.1t or greater, the CT layer having a maximum CT, and a ratio of maximum CT to surface CS of about 0.01 to about 0.5; The method comprising:

[0268] Embodiment 83 83. The method of embodiment 82, wherein the generating the stress profile comprises ion-exchanging a plurality of metal ions into the glass-based substrate to form a metal oxide concentration gradient comprising a non-zero concentration of metal oxide extending along the thickness.

[0269] Embodiment 84 84. The method of embodiment 83, wherein the non-zero concentration of the metal oxide decreases from the first surface to a point between the first surface and the second surface and increases from that point to the second surface.

[0270] Embodiment 85 85. The method of any one of claims 82 to 84, wherein the CT layer has a concentration gradient of the metal oxide.

[0271] Embodiment 86 86. The method of any one of embodiments 82 to 85, further comprising increasing the surface CS by at least about 100 MPa after generating the stress profile.

[0272] Embodiment 87 87. The method of claim 86, wherein creating the stress profile comprises performing a first ion exchange of a first plurality of ions into the glass-based substrate to form a concentration gradient of the metal oxide including a non-zero concentration of the metal oxide extending along the thickness, and increasing the surface Cs comprises performing a second ion exchange of a second plurality of alkali ions into the glass-based substrate with the concentration gradient of the metal oxide.

[0273] Embodiment 88 87. The method of embodiment 86, wherein generating the stress profile comprises performing a first ion exchange of a plurality of ions into the glass-based substrate to form a concentration gradient of the metal oxide extending along the thickness, the concentration gradient comprising a non-zero concentration of the metal oxide, the plurality of ions comprising two different ions having different ionic radii from each other.

[0274] Embodiment 89 In the use of the glass composition in tempered glass, The glass composition comprises, in mole percent: SiO2 in an amount ranging from about 68 to about 75; Al2O3 in an amount ranging from about 12 to about 15; B2O3 in an amount ranging from about 0.5 to about 5, LiO in an amount ranging from about 2 to about 8; Na2O in an amount ranging from about 0 to about 6; MgO in an amount ranging from about 1 to about 4; ZnO in an amount ranging from about 0 to about 3, and CaO in an amount ranging from about 0 to about 5; Including, the glass substrate is ion-exchangeable and amorphous; The glass substrate is a ratio of LiO to RO ranging from about 0.5 to about 1; a difference between the total amount of R2O and the amount of Al2O3 ranging from about -5 to about 0; R ranging from about 0 to about 3 x the difference between the total amount of O (mol %) and the amount of Al2O3, and a ratio of the amount of MgO (mol %) to the total amount of RO (mol %) ranging from about 0 to about 2; indicates one or more of the following: The glass substrate is substantially free of nucleating agents.

[0275] Embodiment 90 In the glass substrate, expressed in mole %, SiO2 in an amount ranging from about 68 to about 75; Al2O3 in an amount ranging from about 12 to about 15; B2O3 in an amount ranging from about 0.5 to about 5, LiO in an amount ranging from about 2 to about 8; Na2O in an amount ranging from about 0 to about 6; MgO in an amount ranging from about 1 to about 4; ZnO in an amount ranging from about 0 to about 3, and CaO in an amount ranging from about 0 to about 5; having a composition comprising the glass substrate is ion-exchangeable and amorphous; The glass substrate is a ratio of LiO to RO ranging from about 0.5 to about 1; a difference between the total amount of R2O and the amount of Al2O3 ranging from about -5 to about 0; R ranging from about 0 to about 3 x the difference between the total amount of O (mol %) and the amount of Al2O3, and a ratio of the amount of MgO (mol %) to the total amount of RO (mol %) ranging from about 0 to about 2; indicates one or more of the following: A glass substrate, wherein the glass substrate is substantially free of nucleating agents.

[0276] Embodiment 91 In the glass substrate, expressed in mole %, SiO2 in an amount ranging from about 68 to about 75; Al2O3 in an amount ranging from about 12 to about 15; B2O3 in an amount ranging from about 0.5 to about 5, LiO in an amount ranging from about 2 to about 8; Na2O in an amount ranging from about 0 to about 6; MgO in an amount ranging from about 1 to about 4; ZnO in an amount ranging from about 0 to about 3, and CaO in an amount ranging from about 0 to about 5; having a composition comprising the glass substrate is amorphous and the glass is strengthened; The glass substrate has a varying concentration of Na2O and is substantially free of nucleating agents.

[0277] Embodiment 92 a ratio of LiO to RO ranging from about 0.5 to about 1; a difference between the total amount of R2O and the amount of Al2O3 ranging from about -5 to about 0; R ranging from about 0 to about 3 x the difference between the total amount of O (mol %) and the amount of Al2O3, and a ratio of the amount of MgO (mol %) to the total amount of RO (mol %) ranging from about 0 to about 2; 92. The strengthened glass substrate of embodiment 91, further comprising any one or more of: [Explanation of symbols]

[0278] 100 Glass products 101, 201, 302 First surface 110, 210, 310 surface CS 120, 220, 320 maximum central tension (CT) 130, 230 Depth of Layer (DOL) 200 Chemically strengthened glass articles 300 Glass-based article of an embodiment 304 Second Surface 312, 340 Stress Profile 315 CS layer 317 DOC 325 CT layer 342 Chemical Depth 400 Ring-on-ring configuration when polishing 410 Polished glass articles 420 Support Ring 430 Load Ring 500 devices 510 Test Stand 512 Solid Base 514 Abrasive paper, sheets with abrasive material 515 Sample holder 516 void 518 Glass-based product samples 520 adhesive tape 530 steel ball

Claims

1. NaNO ３ A glass-based article ion-exchanged in a molten salt bath comprising: a first surface and a second surface opposite the first surface, the first surface defining a thickness (t) of 1 mm or less; a concentration of metal oxide that is non-zero and varies along the thickness range of 0·t to 0.3·t; a stress profile that decreases from the first surface to a value between the first surface and the second surface and increases from that value to the second surface; a compressive stress (CS) layer extending from the first surface to a depth of compression (DOC) that is 0.18·t or greater; a central tension (CT) region of the stress profile, the CT region having the formula: [Equation 1] is defined by where MaxCT is the maximum CT value, given as a positive value in units of MPa, x is the position along the thickness (t) in micrometers, and n is between 1.5 and 5; and SiO in an amount of 60 mol % to 70 mol % 2 , Al in an amount of 6 mol% to 30 mol% 2 O 3 , B in an amount ranging from 0 to 6 mol% 2 O 3 , SnO in an amount ranging from 0 to 1 mol% 2 , TiO in an amount ranging from 0 to 6 mol% 2 , MgO in an amount ranging from greater than 0 to 8 mol %, ZnO in an amount ranging from greater than 0 to 3 mol %, R ranges from 5 to 20 2 The total amount (mol %) of metal oxides represented by Na 2 O and Li 2 R containing O ２ O, and Li in an amount of 2 mol% to 18 mol% 2 O The maximum CT value is in the range of 50 MPa or more and 150 MPa or less, The glass-based article, wherein the CS of the surface is in the range of 150 MPa or more and 1200 MPa or less.

2. The R ２ The Li relative to O ２ The ratio of R to O is 0.5 to 1.

0. ２ O is Li 2 O+Na 2 2. The glass-based article according to claim 1, wherein the glass-based article is O.

3. The Al 2 O 3 is present in an amount from 6 mol% to 17 mol%.

4. The glass-based article according to any one of claims 1 to 3, wherein the CT region has a concentration gradient of a metal oxide.

5. The glass-based article according to any one of claims 1 to 4, wherein 0.25t ≧ DOC ≧ 0.18t.

6. 6. The glass-based article of any one of claims 1-5, wherein all points of the stress profile between the thickness ranges of 0 t to 0.3 t and from greater than 0.7 t have a tangent less than -0.1 MPa / micrometer or greater than 0.1 MPa / micrometer.

7. 7. The glass-based article of any one of claims 1 to 6, further exhibiting a transmittance of 88% or greater over a wavelength range from 380 nm to 780 nm.

8. An electronic device comprising the glass-based article according to any one of claims 1 to 7.

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