Stress profile of glass-based articles with improved drop performance

Abstract

Glass-based articles include a stress profile for providing improved drop performance. A glass-based substrate includes: a glass transition temperature (T g ), a liquid fragility index (m), and a fictive temperature (T f ), wherein T g is less than or equal to 650 °C, T f minus T g is greater than or equal to -30 °C, and m is greater than or equal to 25. The stress relaxation rate is greater than or equal to 10%, 20%, or more. The article can include a lithium-based aluminosilicate composition and a fracture toughness greater than or equal to 0.75 MPa*m 0 . 5 The stress profile includes: a spike region extending from the first surface to an inflection point; and a tail region extending from the inflection point to a center of the glass-based article, the tail region including: a negative curvature region, wherein a second derivative of a function of stress versus depth is negative; a depth of compression (DOC) greater than or equal to 0.22t, and a parabolic region originating from the DOC and extending to the center of the glass-based article.

Description

[0001] This application claims priority to U.S. Provisional Application No. 63 / 083,287, filed September 25, 2020, pursuant to 35 U.S. SC §119, the contents of which are incorporated herein by reference in their entirety. background Technical Field

[0003] This specification generally relates to stress distribution profiles of glass substrates suitable as cover glass for electronic devices. More specifically, this specification relates to providing improved stress distribution profiles and methods for lithium-containing aluminosilicate glasses with improved drop performance. Background Technology

[0005] The mobile nature of portable devices (such as smartphones, tablets, portable media players, personal computers, and cameras) makes them particularly vulnerable to accidental drops onto hard surfaces (such as the ground). These devices often include a cover glass, which can be damaged upon impact with a hard surface. In many of these devices, the cover glass serves as a display cover and may incorporate touch functionality; damage to the cover glass negatively impacts the device's usability.

[0006] When a portable device is dropped onto a hard surface, the glass covering exhibits two main breakage modes. One mode is flexural breakage, caused by the glass bending when the device is subjected to a dynamic load from an impact with the hard surface. The other mode is sharp-contact breakage, caused by damage to the glass surface. Impacts to glass from rough, hard surfaces (e.g., asphalt, granite, etc.) can result in sharp indentations on the glass surface. These indentations become breakage sites on the glass surface, from which cracks can originate and propagate.

[0007] Chemical treatment is a strengthening method used to impart a desired and / or designed stress distribution profile with one or more of the following parameters: compressive stress (CS), depth of compression (DOC), and maximum center tension (CT). Many glass-based articles (including those with designed stress distribution profiles) have the highest or peak compressive stress at the glass surface, which decreases from the peak value away from the surface, and zero stress exists at some internal locations of the glass article before the stress becomes tensile. Chemical strengthening by ion exchange (IOX) of alkali metal glasses is an effective method in this field.

[0008] Traditional ion exchange technology can make glass-based products (especially glass) more resistant to bending breakage by inducing compressive stress in the glass surface. However, ion-exchanged glass may still be susceptible to dynamic sharp contact, due to the high stress concentration caused by localized indentations in the glass resulting from sharp contact.

[0009] Glass manufacturers and handheld device manufacturers continue to strive to improve the resistance of handheld devices to breakage from sharp contact. Solutions range from the cover glass to the frame to prevent the cover glass from directly impacting hard surfaces when the device is dropped. However, due to aesthetic and functional constraints, it is difficult to completely prevent the cover glass from impacting hard surfaces.

[0010] The stress distribution curve needs to be improved to produce excellent drop performance. Summary of the Invention

[0011] This disclosure relates to glass-based articles and methods of manufacturing the same.

[0012] On one hand, a glass substrate includes: a glass transition temperature (T0) g ), liquid fragility index (m) and hypothetical temperature (T) f ), where T g Less than or equal to 650℃, T f Subtract T g The value is greater than or equal to -30℃, and m is greater than or equal to 25.

[0013] In one embodiment, the glass substrate comprises a stress relaxation rate greater than or equal to 10%. In another embodiment, T... g Greater than or equal to 550℃, T f Subtract T g The value is less than or equal to 100°C, and m is greater than or equal to 25. In an embodiment, m is greater than or equal to 30. In an embodiment, m is less than or equal to 60.

[0014] In one embodiment, the glass substrate further comprises: a lithium-based aluminum silicate composition, and a pressure greater than or equal to 0.75 MPa*m. 0.5The fracture toughness. In an embodiment, the lithium-based aluminum silicate composition contains more than 8 mol% lithium oxide (Li₂O). In an embodiment, the lithium-based aluminum silicate composition contains less than 1.0 molar ratio of sodium oxide (Na₂O) to lithium oxide (Li₂O). In an embodiment, the molar ratio of sodium oxide (Na₂O) to lithium oxide (Li₂O) is less than or equal to 0.63. In an embodiment, the lithium-based aluminum silicate composition contains less than 2 mol% of potassium oxide (K₂O) and phosphorus pentoxide (P₂O₅) in an amount less than 2 mol% of the composition. In an embodiment, the lithium-based aluminum silicate composition comprises: 50 mol% to 69 mol% SiO2; 12.5 mol% to 25 mol% Al2O3; 0 mol% to 8 mol% B2O3; greater than 0 mol% to 4 mol% CaO; greater than 0 mol% to 17.5 mol% MgO; 0.5 mol% to 8 mol% Na2O; 0 mol% to 2.5 mol% La2O3; and greater than 8 mol% to 18 mol% Li2O.

[0015] On one hand, a method for manufacturing a glass-based article includes the steps of: preparing a glass composition; and treating the glass composition to form a glass substrate, the glass substrate comprising: a glass transition temperature (T0). g ), liquid brittleness index (m) and hypothetical temperature (T) f ), where T g Less than or equal to 650℃, T f With T g The difference between the two conditions is greater than or equal to -30°C, and m is greater than or equal to 25; the glass substrate is placed under ion exchange conditions of less than or equal to 550°C to form a glass substrate article having a stress relaxation rate of greater than or equal to 10%. In embodiments, the processing for forming the glass substrate includes float glass processing, down-drawing processing, fusible forming processing, slot drawing processing, or roll forming processing. In embodiments, the processing further includes an annealing step.

[0016] Additional features and advantages will be set forth in the following detailed description, and those skilled in the art may partially understand these additional features and advantages from the description, or by practicing the embodiments described herein (including the following detailed description, claims and drawings).

[0017] It should be understood that both the above general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated in and form a part of this specification. The drawings illustrate the various embodiments described herein and, together with the description, serve to explain the principles and operation of the claimed subject matter.

[0018] Brief description of the attached figures

[0019] Several embodiments are described below in conjunction with the accompanying drawings, which are incorporated in and form part of this specification.

[0020] Figure 1 The schematic diagram shows a cross-section of glass having a compressive stress layer on its surface according to the embodiments described and illustrated herein;

[0021] Figure 2 A generalized schematic stress distribution curve of stress (MPa) versus normalized position (z / thickness) from the surface for an embodiment of a glass-based article;

[0022] Figure 3A A plan view of an exemplary electronic device incorporating any glass article disclosed herein;

[0023] Figure 3B for Figure 3A A perspective view of an exemplary electronic device;

[0024] Figure 4 A graph showing the relationship between stress (MPa) and depth (micrometers) from the surface for embodiments and comparative examples of glass-based articles;

[0025] Figure 5 A graph showing the relationship between sodium dioxide (Na2O) concentration and depth for the embodiments;

[0026] Figure 6 A graph showing the relationship between applied fracture stress (MPa) and particle size for embodiments of glass-based articles;

[0027] Figure 7 A graph showing the relationship between stress (MPa) and depth (micrometers) from the surface for embodiments and comparative examples of glass-based articles;

[0028] Figure 8 for Figure 6 The second derivative of the stress distribution curve is plotted.

[0029] Figure 9 This is an excerpt of the stress distribution curve according to an embodiment of a glass-based article;

[0030] Figure 10 A schematic diagram of a device that damages glass products by utilizing the impact of an impacting object.

[0031] Figures 11 to 14 The stress relaxation rate according to the embodiment of the glass substrate; and

[0032] Figure 15 For T gMinimum brittleness (m) and measures to ensure T values ​​less than or equal to 500°C IOX The minimum T with sufficient stress relaxation f -T g The image. Detailed Implementation

[0033] Before describing several exemplary embodiments, it should be understood that this disclosure is not limited to the details of the construction or processing steps described below. The disclosure provided herein can have other embodiments and can be practiced or performed in various ways.

[0034] Throughout this specification, the terms "one embodiment," "some embodiments," "various embodiments," "one or more embodiments," or "embodiment" mean that a particular feature, structure, material, or characteristic described in connection with an embodiment is included in at least one embodiment of this disclosure. Therefore, expressions such as "in one or more embodiments," "in some embodiments," "in various embodiments," "in one embodiment," or "in an embodiment" presented throughout this specification do not necessarily refer to the same embodiment or only one embodiment. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0035] Definition and Measurement Techniques

[0036] The terms "glass-based articles" and "glass-based substrates" are used to refer to any object that is entirely or partially made of glass (e.g., glass or glass-ceramic materials). Laminated glass-based articles include laminates of glass with non-glass materials and laminates of glass with crystalline materials.

[0037] The “base composition” is the chemical composition of the substrate prior to any ion exchange (IOX) treatment. That is, the base composition is not doped with any ions from the IOX. When the IOX treatment conditions prevent the ions supplied by the IOX from diffusing to the center of the substrate, the composition at the center of the IOX-treated glass article is typically the same as the base composition. In one or more embodiments, the central composition at the center of the glass article comprises the base composition.

[0038] It should be noted that the terms “substantially” and “about” are used herein to indicate the degree of uncertainty that may be attributable to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to indicate the extent to which a quantitative representation may differ from the stated reference without causing a change in the essential function of the subject matter. Thus, for example, a glass matrix article that is “substantially free of MgO” means that MgO has not been actively added to or incorporated into the glass matrix article, but may be present as a contaminant in very small amounts. As used herein, the term “about” refers to quantities, dimensions, formulations, parameters, and other quantities and characteristics that are not precise and need not be precise, but may be approximated and / or larger or smaller as needed to reflect tolerances, conversion factors, rounding, measurement errors, and other factors known to those skilled in the art. When the term “about” is used to describe a value or endpoint of a range, this disclosure should be understood to include the specific value or endpoint referred to. Regardless of whether the numerical values ​​or endpoints of a range in the specification are marked “about,” the numerical values ​​or endpoints of a range are intended to include two implementations: one modified by “about” and the other not modified by “about.” It can be further understood that each endpoint of a range is clearly related to, and independent of, the other endpoint.

[0039] Unless otherwise stated, all compositions described herein are expressed as mole percentages (mol%) based on oxides.

[0040] The "stress distribution curve" is a function of stress and the thickness across the glass substrate article. The compressive stress region extends from the first surface to the depth of compression (DOC) of the article and is the area of ​​the article under compressive stress. The central tension region extends from the DOC to include the area of ​​the article under tensile stress.

[0041] As used herein, Depth of Compression (DOC) refers to the depth at which stress within a glass-based article changes from compressive to tensile stress. At DOC, stress transitions from positive (compressive) stress to negative (tensile) stress and thus exhibits a zero stress value. According to convention commonly used in the mechanical field, compression is represented as negative (<0) stress, while tension is represented as positive (>0) stress. However, in this specification, positive stress values ​​are expressed as compressive stress (CS), which is expressed as a positive or absolute value (i.e., as stated herein, CS = |CS|). Furthermore, negative stress values ​​are tensile stress. However, when using the term "tension," stress or center tension (CT) can be expressed as a positive value (i.e., CT = |CT|). Center tension (CT) refers to the tensile stress in the central region or center tension region of a glass-based article. Maximum center tension (maximum CT or CT) 最大The maximum tensile stress may exist in the center tension region (e.g., nominally at 0.5·t) (where t is the article thickness), which allows for variation starting precisely from the center of the location of maximum tensile stress. Peak tension (PT) refers to the maximum tension measured, which may or may not be at the center of the article.

[0042] The "inflection point" of the stress distribution curve is at the depth of the workpiece, where the slope of the curve transitions from steep to gentle. The inflection point can refer to the transition region across the depth where the slope changes. The inflection point stress (CS) is... k Defined as the deeper portion of the CS distribution curve extrapolated to the peak depth (DOL) k The value of the compressive stress at (). The reported DOL k The surface stress gauge is used to measure the stress using known methods. Figure 2 Provide a schematic diagram of the stress distribution curve, including the inflection point stress.

[0043] A non-zero concentration of metal oxides relative to the variation of the metal oxide concentration from the first surface to the depth of layer (DOL) or along at least a majority of the article thickness (t) indicates that stress has been generated in the article as a result of ion exchange. The variation in metal oxide concentration can be referred to herein as a metal oxide concentration gradient. Metal oxides with a concentration that is not zero and varies from the first surface to the DOL or along a portion of the thickness can be described as generating stress in a glass-based article. A concentration gradient or variation of metal oxides is generated by chemically strengthening the glass substrate, wherein multiple first metal ions in the glass substrate exchange with multiple second metal ions.

[0044] As used herein, the terms “exchange depth,” “layer depth” (DOL), “chemical depth of layer,” and “chemical layer depth” are used interchangeably and generally describe the depth of ion exchange facilitated by ion exchange treatment (IOX) targeting specific ions. DOL refers to the depth within a glass substrate (i.e., the distance from the surface of the glass substrate to its interior region) where ions of metal oxides or alkali metal oxides (e.g., metal ions or alkali metal ions) diffuse into the glass substrate, where the ion concentration reaches a minimum as measured by a glow discharge spectrometer (GD-OES). In some embodiments, DOL is given by the exchange depth of the slowest or largest ion introduced by the ion exchange (IOX) treatment. For potassium, DOL (DOL...) K The potassium content of the glass reaches the depth of the potassium content of the underlying substrate. Regarding sodium, DOL (DOL...) Na ( ) refers to the depth to which the sodium content of the glass product reaches the sodium content of the underlying substrate.

[0045] Unless otherwise stated, CT and CS are expressed in megapascals (MPa) in this document, thickness in millimeters, and DOC and DOL in micrometers (μm).

[0046] Compressive stress (including surface / peak CS, CS) 最大 ) and DOL sp The surface stress was measured using a commercially available instrument, such as the FSM-6000 manufactured by Orihara IndustriAlCo., Ltd. (Japan). Surface stress measurement depends on the accurate measurement of the stress optical coefficient (SOC), which is related to the birefringence of the glass. The SOC was then measured according to Procedure C (the glass dish method) of ASTM standard C770-16, entitled "Standard Test Method for Measurement of Glass Stress-Optical Coefficient," the contents of which are incorporated herein by reference in their entirety.

[0047] The maximum center tension (CT) or peak tension (PT) and stress retention value are measured using Scattered Light Polarizer (SCALP) techniques known in the art. The Refractive Near-Field (RNF) method, or SCALP, can be used to measure stress distribution profiles and depth of compression (DOC). When using the RNF method to measure a stress distribution profile, the maximum CT value provided by SCALP is used in the RNF method. More specifically, the stress distribution profile measured by RNF is force-balanced and calibrated to the maximum CT value provided by SCALP measurement. The RNF method is described in U.S. Patent 8,854,623 entitled “Systems and methods for measuring a profile characteristic of a glass sample,” which is incorporated herein by reference in its entirety. More specifically, the RNF method includes placing a glass article adjacent to a reference square, generating a polarization-switched beam that switches between orthogonal polarizations at a rate from 1 Hz to 50 Hz, measuring the power in the polarization-switched beam, and generating a polarization-switched reference signal, wherein the measured power of each of the orthogonal polarizations is within 50% of each other. The method further includes emitting a polarization-switched beam into the glass sample through glass samples and a reference cube at different depths, and then relaying the emitted polarization-switched beam to a signal photodetector using a relay optics system, wherein the signal photodetector generates a polarization-switched detector signal. The method also includes dividing the detector signal by a reference signal to form a normalized detector signal, and determining the distribution curve characteristics of the glass sample from the normalized detector signal.

[0048] Fracture toughness (K) 1CThis indicates the glass composition's resistance to fracture. Fracture toughness is measured on unstrengthened glass articles (e.g., by measuring K0 before ion exchange (IOX) treatment of the glass article). 1C The fracture toughness test method described herein is not applicable to glass that has already undergone IOX treatment. However, fracture toughness measurements performed on the same glass (e.g., glass substrate) prior to IOX treatment, as described herein, are related to the fracture toughness after IOX treatment, and are used accordingly. K is used to measure... 1C The notched short rod (CNSB) method is described in J. Am. Ceram. Soc., 71[6], C-310-C-313 (1988) in Reddy, KPR et al.'s "Fracture Toughness Measurement of Glass and Ceramic Materials Using Chevron-Notched Specimens". The difference is that it uses "Closed-Form Expressions for Crack-Mouth Displacement and Stress Intensity Factors for Chevron-Notched Short Bar and Short Rod Specimens Based on Experimental Compliance Measurements" in NASA Technical Memorandum 83796, pp.1-30 (October 1992) in Bubsey, RT et al.'s "Closed-Form Expressions for Crack-Mouth Displacement and Stress Intensity Factors for Chevron-Notched Short Bar and Short Rod Specimens Based on Experimental Compliance Measurements" to calculate Y*. m Used to measure K 1C The double-torsion method and fixture are described in "The double-torsion testing technique for determination of fracture toughness and slow crack growth of materials: A review" by Shyam, A. and Lara-Curzio, E., J. Mater. Sci., 41, pp. 4093-4104, (2006). The double-torsion measurement method typically produces K values ​​slightly higher than the notched bar method. 1CValues. Unless otherwise stated, all fracture toughness values ​​are measured using the notched bar short bar (CNSB) method.

[0049] The relaxation stress (σ) measured in glass that has undergone IOX treatment. r ) and theoretical non-relaxation stress (σ o The stress relaxation ratio (SR) refers to the ratio of the final measured relaxed stress to the theoretical unrelaxed stress, predicted by the stress distribution curve based on ideal diffusion conditions using a complementary error function (erfc(x)). SR has values ​​less than 1 and greater than 0. The stress relaxation ratio of a substrate or product is the percentage reduction in theoretical unrelaxed stress. For example, for a theoretical unrelaxed stress of 100 MPa (σ... o ) and the measured relaxation stress (σ) of 90 MPa r The stress relaxation rate is 10%, or 1 minus SR and multiplied by 100.

[0050] Theoretical non-relaxation stress (σ) o The ion concentration is determined by measuring the thickness of the IOX-treated product and input into the following linear elastic equation.

[0051]

[0052] Where z is the position, T is the thickness of the transparent material, C is the concentration, B is the linear lattice expansion coefficient, E is Young's modulus, and ν is Poisson's ratio. Based on the ionic radii of Li+ (0.08 nm), Na+ (0.102 nm), and K+ (0.0138 nm), 1 mol% Li+→Na+ 10x increases by approximately 60% compared to 1 mol% Na+→K+; therefore, B is used as a value of 0.6 ppk / mol% Li+→Na+. For the glass discussed, E typically ranges from ≥60 to ≤90 GPa; ν typically ranges from ≥0.2 to ≤0.24.

[0053] Measuring relaxation stress (σ) r The surface stress is determined by surface stress measurements performed, for example, by a near-field refraction (RNF) method, and does not include any sharp or steep surface distribution curves.

[0054] Molten glass exhibits different structures at different temperatures. This structure can be solidified (or frozen) depending on the heat treatment the glass undergoes. The hypothetical temperature (T0) for solid glass used in this paper is... fThe imaginary temperature is the temperature at which a molten glass has the same structure as a solid glass. For example, a discussion of imaginary temperatures can be found in "Fictive Temperature and the Glassy State" by Mauro et al., J. Am. Ceram. Soc., 2009, 92:75-86, the contents of which are incorporated herein by reference in their entirety. According to this disclosure, the calculation of the imaginary temperature relating to the thermal history and glassy properties of a particular glass composition can follow established methods. f The Guo method, described in Guo et al.'s "Unified approach for determining enthalpic fictive temperature of glasses with arbitrary thermal history" in the Journal of Non-Crystalline Solids, 357(2011) 3230-3236, is incorporated herein by reference in its entirety. The Guo method uses differential scanning calorimetry (DSC) at a DSC upscan rate of 10 K / min to generate the first and second upscans of the heat capacity versus temperature curve. The three-step procedure includes: (a) First, using area matching, calculating the hypothetical temperature T of the recycled glass in the second upscan. f2 (b) Next, the area between the scan curves on the two DSCs is calculated, given the difference in enthalpy between the formed glass (H1) and the recycled glass (H2); and (c) Finally, the hypothetical temperature T of the formed glass is determined by area matching using equation (A). f1 .

[0055]

[0056] Unless otherwise stated, all T f The values ​​are all determined by the Guo method.

[0057] The glass transition temperature (T) of the materials used in this article g ) for having 10 12 The equilibrium viscosity at temperature (Pa-s). Unless otherwise specified, all T values ​​are... g Values ​​are determined in accordance with ASTM C1350M-96 (2019) ("Standard Test Method for Measurement of Viscosity of Glass Between Softening Point and Annealing Range (Approximately 10 8Pa·s to Approximately 10 13 Pa·s) by Beam Bending” (measured by bending beam between the softening point and the annealing range (approximately 10) 8 Pa·s to approximately 10 13 The viscosity is determined by the viscosity versus temperature curve generated by the standard test method for glass viscosity (Pa·s).

[0058] The liquid brittleness index (m) of the material used in this paper is the glass transition temperature (T). g The rate of viscosity change as a function of temperature. The liquid brittleness index (m) of composition (x) is defined as:

[0059]

[0060] Use one or more viscometers to generate viscosity versus temperature curves. The value of the liquid brittleness index (m) is the curve of log(viscosity) versus 1 / T at T=T. g The slope at 10°C. Unless otherwise stated, all m values ​​are determined by the viscosity versus temperature curves produced according to the following combination of test methods: ASTM C-965-96 (2017) (“Standard Practice for Measuring Viscosity of Glass Above the Softening Point”); STM C1351M-96 (2017) (“Standard Test Method for Measurement of Viscosity of Glass Between 10°C and 10°C”). 4 Pa·s and 10 8 Pa·s by Viscous Compression of a Solid Right Cylinder” (measured by the viscous compression of glass at 10 rpm using a solid right cylinder) 4 Pa·s and 10 8 The standard test method for the viscosity between Pa·s); and ASTM C1350M-96 (2019) ("Standard Test Method for Measurement of Viscosity of Glass Between Softening Point and Annealing Range (Approximately 10 Pa·s)" ... 8 Pa·s to Approximately 10 13Pa·s) by Beam Bending” (measured by bending beam between the softening point and the annealing range (approximately 10) 8 Pa·s to approximately 10 13 (Standard test method for glass viscosity (Pa·s)).

[0061] Glass transition temperature (T) of composition x g Both the brittleness of the composition and the brittleness of the glass can be expressed as an extension of empirically determined fitting coefficients. Such extensions are discussed in detail in U.S. Patent Application 12 / 896,355, filed October 1, 2010, entitled “METHODS AND APPARATUS FOR PREDICTING GLASS PROPERTIES,” the contents of which are incorporated herein by reference in their entirety.

[0062] Overview of the properties of glass-based products

[0063] The glass-based articles described herein are designed to have improved drop performance for high-damage-resistant glass. The glass-based articles described herein are designed to utilize stress relaxation compositions and properties. This results in an S-shaped stress distribution curve before the depth of compression (DOC) and a parabolic curve after the DOC.

[0064] The glass substrates herein are designed to achieve the desired S-shaped distribution curve at a reasonable ion exchange (IOX) treatment time and below the selected IOX treatment temperature. In one or more embodiments, the glass stress substrates achieve stress relaxation rates greater than or equal to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or greater. The compositions for suitable glass substrates are accordingly designed to contain the following desired combinations: glass transition temperature (T0). g ), liquid brittleness index (m) and hypothetical temperature (T) f In one or more embodiments, for IOX processing temperatures less than or equal to 500°C, T g Less than or equal to 650℃, T f Subtract T g The value of T (e.g., T) f With T g The difference between them is greater than or equal to -30℃, while m is greater than or equal to 25.

[0065] In one or more embodiments, the article of manufacture comprises a lithium-based aluminum silicate composition and a strength greater than or equal to 0.75 MPa*m. 0.5The fracture toughness. The stress distribution curve includes: a peak region extending from the first surface to the inflection point; and a tail region extending from the inflection point to the center of the glass substrate, the tail region including: a negative curvature region, where the second derivative of stress as a function of depth is negative; a DOC greater than or equal to 0.22t; and a parabolic region originating from the DOC and extending to the center of the glass substrate.

[0066] Under ideal conditions, the shape and values ​​of the stress distribution curve in ion-exchange glass are expected to follow the classical diffusion equation. The solution to this equation indicates that, in the case of a single boundary with unrestricted ion diffusion, the stress distribution curve should be a complementary error function (erfc(x)). As used herein, the terms "error function" and "erf" refer to a function that is twice the integral of the normalized Gaussian function between 0 and x / σ√2. The terms "complementary error function" and "erfc" are equal to 1 minus the error function; that is, erfc(x) = 1 - erf(x). For boundary cases (e.g., ions diffuse from opposite surfaces to the center of the glass), the diffusion of enhanced cations follows the complementary error function until the ions meet at the center of the glass, after which the entire diffusion distribution curve may be better approximated by a parabolic shape distribution curve of the ion distribution. The stress distribution curve is directly related to the ion distribution inside the glass. Therefore, the stress distribution curve should resemble the ion distribution, regardless of whether the ion distribution is based on the complementary error function or the parabolic function.

[0067] Some glasses may exhibit discrepancies between the expected and observed stress distribution curves. This could be due to stress relaxation present in the glass, as well as additional annealing effects. In the presence of stress relaxation, an S-shaped distribution curve with a negative curvature region is achieved, where the second derivative of stress as a function of depth is negative. In the negative curvature region, the slope of the stress distribution curve in the compression layer between the surface and the depth of compression (DOC) includes at least one region where the slope value changes sign, indicating that the slope (S) of the stress distribution curve is not a monotonically increasing or decreasing function. Conversely, the slope (S) changes from a decreasing pattern to an increasing pattern, and vice versa, thus defining the S-shaped region of the stress distribution curve.

[0068] The stress distribution curves presented in this paper exhibit an S-shape before DOC and a parabolic shape after DOC. During ion exchange (IOX) treatment, stress relaxation and ion diffusion occur simultaneously. When diffusion is rapid, the time duration at the IOX temperature limits stress relaxation to a very low level, and a nearly linear decay distribution curve from the sample surface to depth is expected. Favorable glass compositions will have a reasonably slow diffusion rate to enhance stress relaxation and achieve the distribution curves presented in this paper. However, slower diffusion requires longer IOX times and higher IOX temperatures. The IOX time can be reduced as the IOX temperature increases. However, increasing the IOX temperature leads to higher processing costs and the potential release of undesirable oxide gases. In some glass compositions, it is easier to optimize the IOX temperature versus diffusion rate compared to other glasses.

[0069] Typically, the stress distribution curves presented in this paper are not brittle, thus a glass composition suitable for the high brittleness limit is desired. Therefore, a suitable glass composition used in this paper has a strength greater than or equal to 0.75 MPa*m. 0.5 Fracture toughness; preferably greater than or equal to 0.8 MPa*m. 0.5 The preferred value is greater than or equal to 0.85 MPa*m. 0.5 Specifically, measured using the mountain-shaped notch short rod method, the suitable glass composition used in this paper has a strength greater than or equal to 0.75 MPa*m. 0.5 Fracture toughness; preferably greater than or equal to 0.8 MPa*m. 0.5 The preferred value is greater than or equal to 0.85 MPa*m. 0.5 From the perspective of the glass composition, the presence of K₂O and P₂O₅ reduces the brittle limit. In one or more embodiments, the total amount of potassium oxide (K₂O) and phosphorus pentoxide (P₂O₅) in the glass composition is less than 2 mol% (e.g., K₂O + P₂O₅ < 2 mol%). Glass compositions containing Li₂O exhibit higher fracture toughness compared to glasses containing only Na₂O. In one or more embodiments, the Li₂O content is greater than that of Na₂O. In other words, in one or more embodiments, the molar ratio of sodium oxide (Na₂O) to lithium oxide (Li₂O) at the center of the glass substrate is less than 1.0. High fracture toughness may also be associated with improved damage resistance (lower damage depth for the same force).

[0070] The glass substrate described in this paper is advantageous because it is designed to have excellent resistance to deep damage, and its stress distribution is not fragile by utilizing stress where needed. The distribution curves described in this paper are applicable to many glass styles (including 2.5D designs), where the glass thickness gradually narrows to have a much lower thickness at the edges. Without being bound by theory, it should be understood that the glass properties can be improved by removing the tension from the edges over a longer diffusion duration. The advantage of the methods described in this paper is that they are feasible for large-scale manufacturing using existing equipment and can be completed within a reasonable timeframe. The use of the longer diffusion duration described in this paper is expected to provide good performance in 2.5D configurations.

[0071] Lithium aluminosilicate glass will now be described in detail according to various embodiments. Alkali metal aluminosilicate glasses have good ion exchange properties, and high strength and high toughness have been achieved in alkali metal aluminosilicate glasses using chemical strengthening methods. Sodium aluminosilicate glass is a highly ion-exchangeable glass with high glass formability and quality. Lithium aluminosilicate glass is a highly ion-exchangeable glass with high glass quality. Substituting Al2O3 into the silicate glass network increases the interdiffusion of monovalent cations during ion exchange. By chemical strengthening in a molten salt bath (e.g., KNO3 or NaNO3), glasses with high strength, high toughness, and high resistance to indentation cracks can be achieved. The stress distribution curve achieved through chemical strengthening can have various shapes, thereby increasing the drop performance, strength, toughness, other properties, and improving scratch resistance of glass products.

[0072] Therefore, lithium aluminum silicate glass, with its excellent physical properties, chemical durability, and ion-exchangeability, has attracted attention as a cover glass. Through different ion-exchange treatments, greater center tension (CT), depth of compression (DOC), and compressive stress (CS) can be achieved. The stress distribution curves described herein provide enhanced drop performance for lithium-containing glass products.

[0073] In the embodiments of the glass compositions described herein, the concentrations of the constituent components (e.g., SiO2, Al2O3, Li2O, etc.) are given as mole percentages (mol%) on an oxide basis unless otherwise specified. It should be understood that any of the various ranges of a component can be combined individually with any of the various ranges of any other component.

[0074] This article discloses an ion exchange method and stress distribution curves for lithium aluminum silicate glass compositions. The stress distribution exhibits scratch resistance. (Refer to...) Figure 1 The glass has a thickness t and a compression depth (DOC) extending from the surface to the first region of compressive stress (e.g., Figure 1The first and second compressive stress layers 120, 122) and the second region extending from the DOC to the center or interior region of the glass under tensile stress or central tension (CT) (e.g., Figure 1 The central area (130).

[0075] Compressive stress (CS) typically has a maximum or peak value at the surface of the glass (but this is not always the case, as the peak can occur at a depth of some distance from the surface), and CS varies as a function with respect to the distance d from the surface. See again... Figure 1 The first compressive stress layer 120 extends from the first surface 110 to a depth d1, while the second compressive stress layer 122 extends from the second surface 112 to a depth d2. These sections together define the compression or CS of the glass 100.

[0076] Two compressive stress layers ( Figure 1 The compressive stress of 120, 122) is balanced by the tension stored in the central region (130) of the glass.

[0077] Figure 2 This diagram illustrates the generalized stress distribution curve, which includes a peak region extending near the surface to the inflection point and a tail region extending deeper into the glass towards the center. The stress values ​​in this generalized curve are not absolute; this is indicated by the inclusion of "y" in the non-zero y-axis values. The stress distribution curve includes: the compressive stress CS at the surface, and the layer depth (DOL) of the peak region. sp (Related to the diffusion depth of ions near the peak), stress CS at the inflection point k (Stress at the asymptotic extrapolation points of the peak and depth distribution curve regions), Depth of Compression (DOC) (the location where stress first becomes zero on the inner side of the glass and its sign changes from compression to tension), and Center Tension (CT) (stress at the center of the glass). In the peak region, there exists a region of negative curvature where the second derivative of stress as a function of depth is negative. Figure 2 In Chinese, for illustrative purposes, compressive stress is conventionally considered positive, while tension is considered negative.

[0078] In one or more embodiments, the shape of the stress distribution curve deeper than the DOC in the central tension (CT) region (where the stress is under tension) can be approximated by an equation. In some embodiments, the stress distribution along the CT region can be approximated by equation (B):

[0079] Stress(x) = Maximum CT – (((Maximum CT·(n+1)) / 0.5 n )·|(x / t)-0.5| n (B)

[0080] In equation (B), stress (x) is the stress value at position x. Here, stress is positive (tension). Maximum CT is the maximum center tension, expressed in MPa, which is a positive value. The value x is the position along the thickness (t), expressed in micrometers, where the range is from 0 to t; x = 0 represents a surface (e.g., Figure 1 In 110), x = 0.5t is the center of the glass-based article, where stress (x) = maximum CT, and x = t is the relative surface (e.g., Figure 1 (112 in the text). The maximum CT used for equation (B) 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), while n is a fitting parameter of 1.5 to 5 (e.g., 2 to 4, 2 to 3, or 1.8 to 2.2), where n = 2 can provide a parabolic stress distribution curve, and an exponent deviating from n = 2 provides a stress distribution curve with a near-parabolic stress distribution curve. The "parabolic shape" distribution curve mentioned herein includes distribution curves fitted to the parabolic equation and those near the parabolic equation.

[0081] In glass-based articles, alkali metal oxides with a non-zero concentration are present, the non-zero concentration of which varies between one or both of the first and second surfaces and the depth of layer (DOL). A stress distribution profile is generated due to the non-zero concentration of the metal oxides, which varies starting from the first surface. The non-zero concentration can vary along a portion of the article thickness. In some embodiments, the concentration of the alkali metal oxides is not zero and varies along a thickness range of about 0.t to about 0.3.t. In some embodiments, the concentration of the alkali metal oxides is not zero and varies along thickness ranges 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, about 0.t to about 0.48.t, or about 0.t to about 0.50.t. The concentration variation can be continuous along the aforementioned thickness ranges. The concentration variation can include a change of about 0.2 mol% or more in the metal oxide concentration along a thickness segment of about 100 micrometers. The variation in the concentration of the metal oxide along a thickness segment of approximately 100 micrometers can be approximately 0.3 mol% or more, approximately 0.4 mol% or more, or approximately 0.5 mol% or more. This variation can be measured using methods known in the art (including microprobes).

[0082] In some embodiments, the concentration variation can be continuous along a thickness range of about 10 micrometers to about 30 micrometers. In some embodiments, between the first surface and the second surface, the concentration of the alkali metal oxide decreases to a value at the first surface and then increases from that value at the second surface.

[0083] The concentration of alkali metal oxides may include more than one metal oxide (e.g., a combination of Na₂O and K₂O). In some embodiments, when using two metal oxides with different ionic radii, the concentration of ions with larger radii is greater than the concentration of ions with smaller radii at shallower depths, while the concentration of ions with smaller radii is greater than the concentration of ions with larger radii at deeper depths.

[0084] In one or more embodiments, the alkali metal oxide concentration gradient extends through most of the thickness t of the article. In some embodiments, the concentration of the metal oxide along the entire thickness of the first and / or second segment may be about 0.5 mol% or higher (e.g., about 1 mol% or higher), and is maximum at the first and / or second surface 0·t, decreasing substantially constantly to a value between the first and second surfaces. At this value, the concentration of the metal oxide along the entire thickness t is minimum; however, the concentration at this point is not zero either. In other words, the non-zero concentration of the particular metal oxide extends along most of the thickness t (as described herein) or throughout the entire thickness t. The total concentration of the particular metal oxide in the glass-based article may range from about 1 mol% to about 20 mol%.

[0085] The concentration of alkali metal oxides can be determined by the baseline amount of metal oxides in the glass substrate ions exchanged to form glass-based articles.

[0086] In one or more embodiments, the glass-based article comprises a lithium-based aluminosilicate composition. In one or more embodiments, the amount of potassium oxide (K₂O) and phosphorus pentoxide (P₂O₅) contained in the lithium-based aluminosilicate composition is less than 2 mol%, less than 1.9 mol%, less than 1.8 mol%, less than 1.7 mol%, less than 1.6 mol%, or less than 1.5 mol%, less than 1.4 mol%, less than 1.3 mol%, less than 1.2 mol%, less than 1.1 mol%, less than 1.0 mol%, less than 0.9 mol%, less than 0.8 mol%, less than 0.7 mol%, less than 0.6 mol%, or less than 0.5 mol%, and / or greater than or equal to 0.01 mol%, and includes all values ​​and subranges thereof. In one or more embodiments, the total amount of potassium oxide (K2O) and phosphorus pentoxide (P2O5) contained in the lithium-based aluminum silicate composition is: greater than or equal to 0 mol% and less than 2 mol%, greater than or equal to 0.01 mol% and less than 1.5 mol%, or greater than or equal to 0.5 mol% and less than 1 mol%, and all values ​​and subranges thereof.

[0087] In one or more embodiments, the lithium-based aluminum silicate composition contains lithium oxide (Li₂O) content greater than 8 mol%, greater than 8.5 mol%, greater than 9 mol%, greater than 9.5 mol%, greater than 10 mol%, greater than or equal to 10.5 mol%, greater than or equal to 11 mol%, greater than or equal to 11.5 mol%, greater than or equal to 12 mol%, greater than or equal to 12.5 mol%, greater than or equal to 13 mol%, greater than or equal to 13.5 mol%, greater than or equal to 14 mol%, or greater than or equal to 15 mol%, and / or less than or equal to 18 mol%. In one or more embodiments, the lithium-based aluminum silicate composition contains lithium oxide (Li₂O) content of: greater than or equal to 8 mol% and less than or equal to 18 mol%, greater than or equal to 9 mol% and less than or equal to 16 mol%, or greater than or equal to 10 mol% and less than or equal to 14 mol%, and all values ​​and subranges thereof.

[0088] In one or more embodiments, the composition at the center of the glass substrate comprises: 50 mol% to 69 mol% SiO2; 12.5 mol% to 25 mol% Al2O3; 0 mol% to 8 mol% B2O3; greater than 0 mol% to 4 mol% CaO; greater than 0 mol% to 17.5 mol% MgO; 0.5 mol% to 8 mol% Na2O; 0 mol% to 2.5 mol% La2O3; and greater than 8 mol% to 18 mol% Li2O. The glass composition is characterized by a (Li2O+Na2O+MgO) / Al2O3 molar ratio of 0.9 to less than 1.3; and Al2O3+MgO+Li2O+ZrO2+La2O3+Y2O3 greater than 23 mol% and less than 50 mol%.

[0089] The glass-based products shown in this article contain those exhibiting high fracture toughness (K). 1C A lithium aluminum silicate glass composition. In some embodiments, the lithium aluminum silicate glass composition is characterized by a pressure of at least 0.75 MPa*m as measured by the notched short rod (CNSB) method. 0.5 K 1C Fracture toughness value.

[0090] In some embodiments, the glass composition exhibits K as measured by the CNSB method. 1CThe value is at least 0.75 (e.g., at least 0.76, at least 0.77, at least 0.78, at least 0.79, at least 0.80, at least 0.81, at least 0.82, at least 0.83, at least 0.84, at least 0.85, at least 0.86, at least 0.87, at least 0.88, at least 0.89, at least 0.90, at least 0.91, at least 0.92, at least 0.93, at least 0.94, at least 0.95, or at least 0.96). In embodiments, the glass composition exhibits K as measured by the CNSB method. 1C Values ​​greater than or equal to 0.75 and less than or equal to 1.00 (e.g., greater than or equal to 0.76 and less than or equal to 0.99, greater than or equal to 0.77 and less than or equal to 0.98, greater than or equal to 0.78 and less than or equal to 0.97, greater than or equal to 0.79 and less than or equal to 0.96, greater than or equal to 0.80 and less than or equal to 0.95, greater than or equal to 0.81 and less than or equal to 0.94, greater than or equal to 0.82 and less than or equal to 0.93, greater than or equal to 0.83 and less than or equal to 0.92, greater than or equal to 0.84 and less than or equal to 0.91, greater than or equal to 0.85 and less than or equal to 0.90, greater than or equal to 0.86 and less than or equal to 0.89, or greater than or equal to 0.87 and less than or equal to 0.88, and all ranges and subranges between the aforementioned values).

[0091] In one or more embodiments, the core composition of the glass-based article comprises: a molar ratio of sodium dioxide (Na2O) to lithium dioxide (Li2O) of less than 1.0 and / or greater than or equal to 0.1, including values ​​less than or equal to 0.99, less than or equal to 0.9, less than or equal to 0.85, less than or equal to 0.8, less than or equal to 0.75, less than or equal to 0.7, less than or equal to 0.65, less than or equal to 0.63, less than or equal to 0.6, less than or equal to 0.55, less than or equal to 0.5, less than or equal to 0.45, less than or equal to 0.4, less than or equal to 0.35, less than or equal to 0.3, less than or equal to 0.25, less than or equal to 0.2, less than or equal to 0.15, and all values ​​and sub-ranges therebetween. In one or more embodiments, the molar ratio of sodium dioxide (Na2O) to lithium dioxide (Li2O) contained in the composition at the center of the glass-based article is greater than or equal to 0.1 and less than 1.0, greater than or equal to 0.15 and less than or equal to 0.9, or greater than or equal to 0.2 and less than or equal to 0.85, and all values ​​and sub-ranges thereof.

[0092] In one or more embodiments, the glass-based article contains a depth of compression (DOC) greater than or equal to 0.22t, greater than or equal to 0.225t, greater than or equal to 0.23t, greater than or equal to 0.235t, greater than or equal to 0.24t, greater than or equal to 0.245t, or greater than or equal to 0.25t, and / or less than or equal to 0.30t, less than or equal to 0.29t, less than or equal to 0.28t, less than or equal to 0.27t, or less than or equal to 0.26t, and all values ​​and sub-ranges thereof. In one or more embodiments, the glass-based article contains a depth of compression (DOC) greater than or equal to 0.22t and less than or equal to 0.30t, greater than or equal to 0.225t and less than or equal to 0.29t, or greater than or equal to 0.23t and less than or equal to 0.8t, and all values ​​and sub-ranges thereof.

[0093] In one or more embodiments, the glass-based article contains a depth of compression (DOC) greater than or equal to 150 micrometers, greater than or equal to 155 micrometers, greater than or equal to 160 micrometers, greater than or equal to 165 micrometers, greater than or equal to 170 micrometers, and all values ​​and subranges thereof.

[0094] In one or more embodiments, the glass-based article includes a t greater than or equal to 0.02 mm and / or less than or equal to 2 mm, and includes: t less than or equal to 1 mm, less than or equal to 0.8 mm, less than or equal to 0.75 mm, less than or equal to 0.73 mm, less than or equal to 0.70 mm, less than or equal to 0.65 mm, less than or equal to 0.6 mm, less than or equal to 0.55 mm, and / or greater than or equal to 0.1 mm, or greater than or equal to 0.5 mm, and includes all values ​​and sub-ranges therein. In one or more embodiments, the glass-based article includes: t greater than or equal to 0.02 mm and less than or equal to 2 mm, greater than or equal to 0.55 mm and less than or equal to 1 mm, greater than or equal to 0.7 mm and less than or equal to 0.8 mm, and includes all values ​​and sub-ranges therein.

[0095] Maximum compressive stress (CS) 最大 The expected value of ) is related to the application of glass-based products. The conditions affecting CS 最大 Factors such as CS. In some implementations, spikes are introduced to increase CS. 最大 In some implementations, no spikes are introduced. In one or more implementations, the maximum compressive stress (CS) contained in the glass-based article is constant regardless of the IOX conditions. 最大The values ​​are greater than or equal to 150 MPa, greater than or equal to 300 MPa, greater than or equal to 350 MPa, greater than or equal to 400 MPa, greater than or equal to 450 MPa, greater than or equal to 500 MPa, greater than or equal to 550 MPa, greater than or equal to 600 MPa, greater than or equal to 650 MPa, greater than or equal to 700 MPa, greater than or equal to 750 MPa, greater than or equal to 800 MPa, greater than or equal to 850 MPa, greater than or equal to 900 MPa, greater than or equal to 950 MPa, greater than or equal to 1000 MPa, greater than or equal to 1050 MPa, greater than or equal to 1100 MPa, greater than or equal to 1150 MPa, or greater than or equal to 1200 MPa, and all values ​​and sub-ranges thereof. In one or more embodiments, the maximum compressive stress (CS) contained in the glass-based article is... 最大 ) greater than or equal to 150 MPa and less than or equal to 1200 MPa, greater than or equal to 250 MPa and less than or equal to 1100 MPa, greater than or equal to 350 MPa and less than or equal to 1000 MPa, and all values ​​and subranges thereof.

[0096] In one or more embodiments, the negative curvature region contains an average compressive stress (CS) greater than or equal to 50 MPa and less than or equal to 120 MPa, greater than or equal to 55 MPa and less than or equal to 115 MPa, or greater than or equal to 60 MPa and less than or equal to 110 MPa, and all values ​​and subranges thereof.

[0097] In one or more embodiments, the peak center tension (CT) in the parabolic region ranges from greater than or equal to 100 MPa and less than or equal to 200 MPa, or greater than or equal to 125 MPa and less than or equal to 175 MPa, and all values ​​and subranges thereof.

[0098] In one or more embodiments, the value of peak center tension (CT)*thickness (t) in the parabolic region ranges from greater than or equal to 80 MPa and less than or equal to 160 MPa, or greater than or equal to 90 MPa and less than or equal to 155 MPa, and all values ​​and subranges thereof.

[0099] In one or more embodiments, the glass-based article includes a retention strength greater than or equal to 170 MPa, measured after impacting an article having a thickness of 600.0 μm with 30-grit sandpaper under a force of 470.0 N. In one or more embodiments, the glass-based article includes a retention strength greater than or equal to 170 MPa, measured after impacting an article having a thickness of 600.0 μm with 80-grit sandpaper under a force of 470.0 N. In one or more embodiments, the glass-based article includes a first retention strength greater than or equal to 170 MPa, measured after impacting an article having a thickness of 600.0 μm with 30-grit sandpaper under a force of 470.0 N, and a second retention strength greater than or equal to 170 MPa, measured after impacting an article having a thickness of 600.0 μm with 80-grit sandpaper under a force of 470.0 N. In one or more embodiments, the first retention strength differs from the second retention strength by ±5 MPa.

[0100] In one or more embodiments, the glass-based article comprises a retained strength, measured after impacting an article having a thickness of 600.0 μm with 30-grit sandpaper with a force of 470.0 N, that is greater than or equal to 170 MPa and less than or equal to 200 MPa, greater than or equal to 175 MPa and less than or equal to 195 MPa, or greater than or equal to 180 MPa and less than or equal to 190 MPa, and all values ​​and subranges thereof.

[0101] In one or more embodiments, the glass-based article comprises a retained strength, measured after impacting an article having a thickness of 600.0 μm with 80-grit sandpaper with a force of 470.0 N, that is greater than or equal to 170 MPa and less than or equal to 200 MPa, greater than or equal to 175 MPa and less than or equal to 195 MPa, or greater than or equal to 180 MPa and less than or equal to 190 MPa, and all values ​​and subranges thereof.

[0102] In one or more embodiments, the glass-based article includes a retained strength measured independently for an article having a thickness of 600.0 μm after impact with 30-grit sandpaper at a force of 470.0 N, which is greater than or equal to 170 MPa and less than or equal to 200 MPa, greater than or equal to 175 MPa and less than or equal to 195 MPa, or greater than or equal to 180 MPa and less than or equal to 190 MPa, and all values ​​and subranges thereof.

[0103] Design of glass substrate

[0104] In one or more embodiments, the glass stress-based substrate achieves a stress relaxation rate of (100*(1-relaxation stress(σ))). r ) and initial stress (σ o The ratio of the glass stress substrate to the glass stress substrate is greater than or equal to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or greater, and / or less than or equal to 100%, less than or equal to 90%, less than or equal to 85%, and includes all values ​​and sub-ranges therein. In one or more embodiments, the stress relaxation rate of the glass stress substrate is greater than or equal to 10% and less than or equal to 100%, greater than or equal to 20% and less than or equal to 90%, greater than or equal to 25% and less than or equal to 80%, and includes all values ​​and sub-ranges therein. The composition for a suitable glass substrate is accordingly designed to contain the desired combination of the following: glass transition temperature (T g ), liquid brittleness index (m) and hypothetical temperature (T) f ).

[0105] In one or more embodiments, T g Greater than or equal to 550°C or less than or equal to 650°C, and all values ​​and sub-ranges thereof. In one or more embodiments, T g 550°C or higher and 650°C or lower, and all values ​​and subranges thereof.

[0106] In one or more embodiments, T f Subtract T g The value is greater than or equal to -30°C or less than or equal to 100°C, and includes all values ​​and sub-ranges thereof. In one or more embodiments, T f Subtract T g The values ​​are greater than or equal to -30°C and less than or equal to 100°C, greater than or equal to 0°C and less than or equal to 95°C, or greater than or equal to 30°C and less than or equal to 90°C, and all values ​​and subranges thereof.

[0107] In one or more embodiments, m is greater than or equal to 25 or less than or equal to 60, and includes all values ​​and subranges thereof. In one or more embodiments, m is greater than or equal to 25 and less than or equal to 60, greater than or equal to 30 and less than or equal to 55, greater than or equal to 35 and less than or equal to 50, and includes all values ​​and subranges thereof.

[0108] The viscosity of the glass substrate contributes to the stress relaxation rate. For glass in a non-equilibrium state, the viscosity measured is very high. The desired ion exchange (IOX) treatment temperature (T) IOX The preferred glass transition temperature range is as follows: Tg -200℃<T IOX <T g -50℃. This upper limit is established to ensure that ion exchange stress is still maintained, rather than all stress being mostly relaxed.

[0109] Stress relaxation is a common phenomenon in glass under stress. As long as stress exists, glass will undergo stress relaxation. Stress relaxation follows the stretching exponent equation, as shown in equation (1).

[0110]

[0111] Where σ r Let σ0 be the relaxation stress, σ0 be the initial stress, t be the physical time, τ be the characteristic relaxation time, and β be the stretching exponent. The stress relaxation based on equation (1) is a characteristic of the base glass substrate, which does not require ion exchange (IOX) during use. It is expected that if the glass undergoes significant stress relaxation under the thermal conditions typically used for IOX, then glass products subjected to IOX under such thermal conditions will also undergo significant stress relaxation. Therefore, stress relaxation based on equation (1) is a way to predict the stress relaxation performance of IOX glass. Within the typical IOX temperature range, the relaxation time can be approximated by the Arrhenius equation (2):

[0112]

[0113] Where τ0 is the relaxation time as temperature T approaches infinity, and E is the activation energy.

[0114] Relaxation time is directly related to viscosity via Maxwell's equation (3):

[0115]

[0116] Where η is viscosity and G is shear modulus. The shear modulus differs from laboratory-measured shear modulus based on laboratory stress relaxation data. Potuzak et al. (Marcel Potuzak, Roger C. Welch, and John C. Mauro, J. of Chem. Phys. 135, 214502 (2011)) discussed stress relaxation measurements in their paper entitled “Topological origin of stretched exponential relaxation in glass,” which is incorporated herein by reference. For the most suitable stress relaxation for laboratory measurements, G is approximately 100 MPa.

[0117] According to the MAP nonequilibrium viscosity model and composition-dependent viscosity model of Mauro et al. (JCMauro, DCAllan, M. Potuzak, Phys. Rev. B80, 094204 (2009)) (XJGuo, JCMauro, DCAllan, MMSmedskjaer, J. Am. Ceram. Soc. 2018; 101: 1169-1179), the expression for the composition dependence of nonequilibrium glass viscosity is as follows:

[0118]

[0119] in

[0120]

[0121] In the viscosity model of equation (4), η eq With η ne Given by equations (6) and (7) respectively. We assume A(x) = A(x) ref ) and ΔH(x)=ΔH(x) ref η is a constant within the range of components under discussion, that is, η ne (T,T f The compositional dependence of x is contained in the last term of equation (7).

[0122]

[0123] Where T g Glass transition temperature (10 12 The isoviscous temperature (Pa·s), where m is the liquid brittleness index.

[0124]

[0125] And η ∞ =10 -2.9 Pa·s is the infinite temperature limit of liquid viscosity (a universal constant for silicate liquids that does not depend on composition).

[0126]

[0127] Where A is a constant related to the attempt frequency, ΔH is the principal activation enthalpy of isostructural flow, and S... ∞ It is the configurational entropy at the infinite temperature limit.

[0128] Based on Mauro's previous enthalpy landscape modeling, there exists an exponentially large number of configurational microstates for more brittle systems, each with an exponentially large number of possible transition states. Therefore, we assume S ∞ As brittleness exhibits an exponential change...

[0129]

[0130] The examples in this article demonstrate the use of this model.

[0131] In one or more embodiments, a method of manufacturing a glass-based article includes the steps of: preparing a glass composition; treating the glass composition to form a glass substrate, wherein the treatment includes: a glass transition temperature (T0). g ), liquid brittleness index (m) and hypothetical temperature (T) f ), where T g Less than or equal to 650℃, T f With T g The difference between them is greater than or equal to -30°C, and m is greater than or equal to 25; the glass substrate is placed under ion exchange conditions of less than or equal to 550°C (including less than or equal to 500°C) to form a glass substrate article, thereby making the stress relaxation rate greater than or equal to 10%.

[0132] glass substrate

[0133] Examples of materials that can be used to form glass-based substrates include glass and glass-ceramic materials. Exemplary glasses that can be used as substrates may include alkali metal aluminosilicate glass compositions or alkali metal-containing aluminoborosilicate glass compositions, and other glass compositions are also contemplated. Specific examples of glass substrates that can be used include, but are not limited to, alkali metal aluminosilicate glasses, alkali metal-containing borosilicate glasses, alkali metal aluminoborosilicate glasses, alkali metal-containing lithium aluminosilicate glasses, or alkali metal-containing phosphate glasses. The glass-based substrate has a base composition that may be ion-exchangeable. As used herein, "ion-exchangeable" means that a substrate containing the composition is capable of exchanging cations located at or near the substrate surface with larger or smaller cations of the same valence.

[0134] In one or more embodiments, the glass substrate may include lithium-containing aluminosilicate.

[0135] In some embodiments, a glass substrate can be formed using any composition capable of forming a stress distribution profile. In some embodiments, a glass substrate can be formed using the glass composition described in U.S. Application 16 / 202,691, filed November 28, 2018, entitled "Glasses with Low Excess Modifier Content," the entire contents of which are incorporated herein by reference. In some embodiments, glass articles can be formed using the glass composition described in U.S. Application 16 / 202,767, filed November 28, 2018, entitled "Ion-Exchangeable Mixed Alkali Aluminosilicate Glasses," the entire contents of which are incorporated herein by reference.

[0136] The characteristics of a glass substrate can lie in its formability. For example, a glass substrate can be float-formed (i.e., formed by a float process), drawn down, and more specifically, fused or slot-drawn (i.e., formed by a draw process, such as a fusion drawing or slot drawing process). In embodiments, the glass substrate can be roll-formed. For glass-ceramics, a ceramicizing step may be included. Other forming methods can be used for both glass and glass-ceramics.

[0137] Some embodiments of the glass substrates described herein can be formed using a pull-down process. The pull-down process produces glass substrates with a uniform thickness relative to the original surface. Since the average flexural strength of a glass article is controlled by the number and size of surface defects, the original surface with minimal contact has higher initial strength. Furthermore, pull-down glass articles have very flat and smooth surfaces that can be used for final applications without the need for expensive grinding and polishing.

[0138] Some embodiments of glass substrates can be described as melt-forming (i.e., formed using a fusion drawing process). The melting process uses a drawing container with grooves for receiving molten glass material. A weir in the grooves opens at the top along the length of the grooves on both sides. When the grooves are filled with molten material, molten glass overflows the weir. Due to gravity, the molten glass flows down the outer surfaces of the drawing container, becoming two flowing glass films. These outer surfaces of the drawing container extend downwards and inwards, joining at the lower edge of the drawing container. The two flowing glass films join together at this edge to fuse and form a single flowing glass article. The advantage of the fusion drawing method is that, because the two glass films flowing out of the grooves fuse together, the outer surface of the resulting glass article does not come into contact with any part of the equipment. Therefore, the surface properties of the fusion-drawn glass article are not affected by this contact.

[0139] Some embodiments of the glass substrates described herein can be formed using a slot drawing process. The slot drawing process differs from the fusion drawing method. In the slot drawing process, molten raw glass is supplied to a drawing container. The bottom of the drawing container has an open slot with nozzles extending along its length. The molten glass flows through the slot / nozzle and is drawn downwards as a continuous glass article into the annealing region.

[0140] In one or more embodiments, the base composition comprises: 50 mol% to 69 mol% SiO2; 12.5 mol% to 25 mol% Al2O3; 0 mol% to 8 mol% B2O3; greater than 0 mol% to 4 mol% CaO; greater than 0 mol% to 17.5 mol% MgO; 0.5 mol% to 8 mol% Na2O; 0 mol% to 2.5 mol% La2O3; and greater than 8 mol% to 18 mol% Li2O. The glass composition is characterized by: (Li2O+Na2O+MgO) / Al2O3 being 0.9 to less than 1.3; and Al2O3+MgO+Li2O+ZrO2+La2O3+Y2O3 being greater than 23 mol% and less than 50 mol%.

[0141] In one or more embodiments, the glass substrate described herein may exhibit an amorphous microstructure and may be substantially free of crystals or microcrystals. In other words, in some embodiments, the glass substrate does not include glass-ceramic materials.

[0142] In one or more embodiments, an annealing step is performed after ion exchange. That is, the annealing step is optional. Annealing at a temperature of, for example, 500°C ± 50°C for a duration of approximately 15 to 60 minutes can be used to achieve a deeper depth of compression (DOC) and / or stress relaxation rate.

[0143] Ion exchange (IOX) treatment

[0144] Chemical strengthening of a glass substrate having a base composition is achieved by placing an ion-exchangeable glass substrate in an ion-exchange medium. In embodiments, the ion-exchange medium may be a molten bath containing cations (e.g., K+, Na+, Ag+, etc.), wherein the cations diffuse into the glass, while smaller alkali metal ions (e.g., Na+, Li+) of the glass diffuse into the molten bath. Replacing smaller cations with larger cations generates compressive stress near the surface of the glass. Tensile stress is generated within the glass to balance the near-surface compressive stress.

[0145] Ion exchange treatment can be a standalone thermal diffusion treatment or an electrodiffusion treatment. Non-limiting examples of ion exchange treatment involving immersion of glass in multiple ion exchange baths with cleaning and / or annealing steps between immersions are described in U.S. Patent 8,561,429, entitled “Glass with Compressive Surface for Consumer Applications,” published October 22, 2013, and filed July 11, 2008, by Douglas C. Allan et al., wherein the glass is strengthened by multiple successive ion exchange treatments involving immersion in salt baths of varying concentrations; and in U.S. Provisional Patent Application 61 / 084,398, entitled “Dual Stage Ion Exchange for Chemical Strengthening of…”, published November 20, 2012, and filed July 29, 2008, by Christopher M. Lee et al. U.S. Patent 8,312,739, "Glass" (two-stage ion exchange for chemically strengthened glass), describes a process in which ion exchange is performed in a first bath diluted with effluent ions, followed by immersion in a second bath having a lower concentration of effluent ions than the first bath, thereby strengthening the glass. The contents of U.S. Patents 8,561,429 and 8,312,739 are incorporated herein by reference in their entirety.

[0146] After ion exchange treatment, it should be understood that the composition of the glass surface can differ from that of the freshly formed glass substrate (i.e., the glass substrate before ion exchange treatment). This is due to the presence of an alkali metal ion (e.g., Li) in the freshly formed glass. + Or Na + ) are respectively subjected to larger alkali metal ions (e.g., Na) + or K +(This is replaced by...) However, in the embodiment, the glass composition at or near the center of the depth of the glass article still has the composition of the newly formed glass substrate.

[0147] In one or more embodiments, the potassium salt comprises: KNO3, K2CO3, K3PO4, K2SO4, K3BO3, KCl, or combinations thereof.

[0148] In one or more embodiments, the sodium salt comprises: NaNO3, Na2CO3, Na3PO4, Na2SO4, Na3BO3, NaCl, or a combination thereof.

[0149] In one or more embodiments, the lithium salt comprises: LiNO3, Li2CO3, Li3PO4, Li2SO4, Li3BO3, LiCl, or combinations thereof.

[0150] In one or more embodiments, the potassium salt comprises KNO3, the sodium salt comprises NaNO3, and the lithium salt comprises LiNO3.

[0151] After IOX processing, the optional annealing steps described above can be applied.

[0152] In one or more embodiments, a method of manufacturing a glass-based article includes the step of: subjecting a glass-based substrate having opposing first and second surfaces having a defined substrate thickness (t) and a lithium-based aluminosilicate composition to ion exchange treatment to form a glass-based article, the ion exchange treatment comprising: a first molten salt bath and a second molten salt bath; wherein the glass-based article comprises: a pressure greater than or equal to 0.75 MPa*m 0.5 The fracture toughness; and the stress distribution curve, including: a peak region extending from the first surface to the inflection point; and a tail region extending from the inflection point to the center of the glass substrate, the tail region including: a negative curvature region, wherein the second derivative of stress as a function of depth is negative; a compression depth (DOC) greater than or equal to 0.22t; and a parabolic region originating from the DOC and extending to the center of the glass substrate.

[0153] Terminal products

[0154] The glass-based articles disclosed herein can be incorporated into another article (e.g., articles having a display (or display article) (e.g., consumer electronics, including mobile phones, tablet computers, computers, navigation systems, etc.), building articles, transportation articles (e.g., vehicles, trains, aircraft, ships, etc.), appliance articles, or any article requiring some transparency, scratch resistance, abrasion resistance, or a combination thereof). Figure 3A and Figure 3B The illustrations are exemplary articles in conjunction with any glass articles disclosed herein. Specifically, Figure 3A and Figure 3B The illustrated consumer electronic device 200 includes: a housing 202 having a front surface 204, a rear surface 206, and a side surface 208; electrical components (not shown) at least partially or entirely located inside the housing, including at least a controller, memory, and a display 210 at or near the front surface of the housing; and a cover 212 located at or on the front surface of the housing to cover the display. In some embodiments, at least a portion of at least one of the cover 212 and / or the housing 202 may include any glasswork disclosed herein.

[0155] Example

[0156] The various implementation methods will be further clarified through the following examples. In these examples, before strengthening, the example is referred to as a "substrate". After strengthening, the example is referred to as an "article" or "glass-based article".

[0157] In the following examples, glass substrates according to composition A or B are subjected to ion exchange, and the resulting articles are tested. Compositions A and B, and the glass substrates produced therefrom, have the following properties.

[0158] Composition A: 17.83 mol% Al₂O₃, 6.11 mol% B₂O₃, 4.41 mol% MgO, 1.73 mol% Na₂O, 58.39 mol% SiO₂, 0.08 mol% SnO₂, 0.18 mol% K₂O, 0.02 mol% Fe₂O₃, 0.58 mol% CaO, and 10.66 mol% Li₂O (0.00 mol% SrO, 0.00 mol% ZnO, and 0.00 mol% P₂O₅); and the molar ratio of Na₂O / Li₂O is 0.16. The glass substrate according to composition A has a strength of 0.85 mPa / MPa*m. 0.5 Fracture toughness; T at approximately 660℃ f T, approximately 617℃ g T f With T g The difference between them is approximately 43°C; the liquid brittleness index (m) is 35.

[0159] Composition B comprises: 12.88 mol% Al₂O₃, 1.84 mol% B₂O₃, 2.86 mol% MgO, 2.39 mol% Na₂O, 70.96 mol% SiO₂, 0.07 mol% SnO₂, 0.02 mol% Fe₂O₃, 8.13 mol% Li₂O, and 0.85 mol% ZnO (0.00 mol% K₂O, 0.00 mol% CaO, 0.00 mol% SrO, and 0.00 mol% P₂O₅); and the molar ratio of Na₂O / Li₂O is 0.29. The glass substrate according to composition B has a strength of 0.8 mPa MPa*m. 0.5 Fracture toughness.

[0160] The stress distribution curves of the experimental examples in this paper were measured using the refractive near-field (RNF) method, where the CT was matched with the CT measurements provided by the scattering polarization method using the SCALP-5 instrument manufactured by Glassstress Co. in Estonia. Furthermore, due to the limitations of the RNF in providing accurate information in the first ~2 μm of the stress distribution curve caused by the size of the beam used in this measurement technique, the RNF data were extrapolated to the surface to find the stress at the surface, thus also matching the estimated stress measurements performed using the FSM-6000LE instrument from Orihara, Japan. Therefore, the total stress distribution curve was matched with the CT at the center of the sample measured by the SCALP instrument using a 365 nm light source and the CS at the surface measured by the FSM-6000LE instrument, providing an accurate representation of the entire stress distribution curve from the surface to the center of the sample.

[0161] As used herein, the term "retained strength" refers to the strength of a glass article after damage has been introduced by an impact force when the article is bent to apply tensile stress. The "surface impact test" method for introducing damage, as described in U.S. Patent Publication No. 2019 / 0072469A1, is incorporated herein by reference. For example, equipment used for impact testing of glass articles... Figure 10The device is shown as component symbol 1100. Device 1100 includes a pendulum 1102, which includes a weight 1104 attached to a pivot 1106. As used herein, the term "weight on a pendulum" refers to a weight suspended by an arm and connected to a pivot. Thus, the weight 1104 shown is connected to the pivot 1106 by an arm 1108. Weight 1104 includes a base 1110 for receiving a glass article, to which the glass article is secured. Device 1100 further includes an impact object 1140, positioned such that when weight 1104 is released from a position at an angle greater than zero from its equilibrium position, the surface of weight 1104 contacts impact object 1140. Impact object includes a friction sheet with a frictional surface for contact with the outer surface of the glass article. The friction sheet may contain sandpaper and may have a grit size in the range of 30 grit to 400 grit or 100 grit to 300 grit (e.g., 30 or 80 grit).

[0162] For the purposes of this disclosure, the impact object is in the form of a 30- or 80-grit sandpaper disc with a diameter of 6 mm, fixed to the device. A glass artifact with a thickness of approximately 600.0 μm is fixed to the weighing hammer. A new sandpaper disc is used for each impact. Damage to the glass artifact is caused by swinging the arm of the device to an angle of approximately 90° under an impact force of approximately 470 N. Approximately 10 samples of each glass artifact are subjected to the impact.

[0163] The glass article fractured under four-point bending (4PB) 12 hours or more after damage introduction. The damaged glass article was placed on a support rod (support span), with the damaged area between the bottom (i.e., the tension side) and the loading path (loading span). For the purposes of this disclosure, the loading span was 18 mm, and the support span was 36 mm. The radius of curvature of the load and support rod was 3.2 mm. A screw-driven testing machine was used. The glass was loaded at a constant displacement rate of 5 mm / min until it broke. The 4PB test was conducted at a temperature of 22°C ± 2°C and a relative humidity of 50% ± 5%.

[0164] Calculate the applied fracture stress (or applied failure stress) σ in the four-point bend (4PB) using equation (C). app .

[0165]

[0166] Where P is the maximum breaking load, L (=36mm) is the distance between the support rods (support span), a (=18mm) is the distance between the loading rods (loading span), b is the width of the glass plate, h is the thickness of the glass plate, and ν is the Poisson's ratio of the glass composition. In equation (C), (1 / (1-v) 2 The stiffening effect of the plate was considered. In the four-point bend, the stress was constant across the loading span; therefore, the damage site was under Mode I uniaxial tensile stress loading. The stress rate for the four-point bend test on the samples was estimated to be between 15 and 17 MPa per second. The retained strength of the glass composition was the highest applied fracture stress without breakage.

[0167] Example 1-2 and AB (comparison)

[0168] Table 1 provides a summary of the dual ion exchange (DIOX) conditions using potassium (K) and sodium (Na) nitrates as illustrated in Examples 1-2. A substrate of composition A with a thickness of 800 micrometers was used. The DIOX conditions included preheating at 380°C for 10 minutes and were the same as in Examples 1-2. Table 1 also shows the following data: weight gain percentage, compressive stress (CS), and inflection point layer depth (DOL). k The substrate is then cleaned to remove excess salt, including the center tension (CT). Both Step I and Step II involve adding 0.5% by weight of silica to the IOX bath. Between Step I and Step II, the substrate is cleaned to remove excess salt.

[0169] Table 1

[0170]

[0171]

[0172] *Steps I and II each include the addition of 0.5% by weight of silica.

[0173] Examples 1-2 were annealed at 500°C after DIOX. Table 2 provides CT data and DOC (μm).

[0174] Table 2

[0175]

[0176] Table 3 provides a summary of single ion exchange (SIOX) conditions for Examples AB (Comparative) using potassium (K), sodium (Na), and lithium (Li) nitrates as described. Example A used an 800-micron thick substrate of composition A. Example B used an 800-micron thick substrate of composition B. Table 3 also shows the following data: compressive stress (CS), compressive stress at the inflection point (CS). k ), inflection point layer depth (DOL) kThe values ​​for center tension (CT) and depth of compression (DOC) are also measured. The IOX step involves adding 0.5% by weight of silica to the IOX bath.

[0177] Table 3

[0178]

[0179] *Includes the addition of 0.5% by weight of silica.

[0180] Figure 4 Provide stress distribution curves (stress (MPa) and depth (micrometers) for Examples 1-2 and AB (comparison). Figure 4 The negative curvature region is shown as follows: For Example 1, the negative curvature region includes a depth of approximately 20 to approximately 140 micrometers, and for Example 2, the negative curvature region includes a depth of approximately 10 to approximately 160 micrometers. Figure 5 This is a graph showing the relationship between sodium dioxide (Na₂O) concentration and depth as measured by GD-OES for Example 1. The solid line represents the linear fit of the Na₂O distribution curve. As a result of force balance, the surface CS is equal to CS = BEΔC / (1-v), where ΔC = C₀ - C₀. ave The surface Na₂O concentration minus the average Na₂O concentration through the thickness, B is the linear lattice expansion coefficient, E is Young's modulus, and ν is Poisson's ratio. Based on... Figure 5 C0 = 10.2, while C ave =5.1. Therefore, the theoretical non-relaxation stress (σ) o Ignoring stress relaxation, the pressure is approximately over 300 MPa, and B is assumed to be about 0.6 ppk / mol%. (e.g., Tandia et al., Journal of Non-Crystalline Solids, 358(2012) 316-320). In the paper cited here, the authors discuss Na+→K+IOX with a coefficient B of approximately 1 ppk / mol%. Based on the ionic radii of Li+ (0.08 nm), Na+ (0.102 nm), and K+ (0.0138 nm), 1 mol% Li+→Na+IOX would result in approximately a 60% increase compared to 1 mol% Na+→K+; therefore, B is used with a value of 0.6 ppk / mol% for Li+→Na+. E is 83 GPa, and ν is 0.22. Figure 4 The stress distribution curve measured for Example 1 shows a surface stress of approximately 115 MPa when the steep surface distribution curve is ignored (measured relaxation stress (σ)). r Therefore, the stress relaxation in this example is approximately 60% (e.g., (300-115) / 300).

[0181] According to the method described above, the retained strength of the article of Example 1 was determined by surface impact testing in a 4-point bending (4PB) test after damage was introduced. In the first set of experiments, the first retained strength was determined by damage impact relative to 30-grit sandpaper. In the second set of independent experiments, the second retained strength was determined by damage impact relative to 80-grit sandpaper.

[0182] Figure 6 The graph shows the relationship between applied fracture stress (MPa) and grit size for Example 1, where the average first retention strength is 185 MPa for 30 grit and the average second retention strength is 189 MPa for 80 grit. 30 grit sandpaper typically causes deeper damage compared to 80 grit sandpaper. Surprisingly, for Example 1, the second retention strength after impact with 30 grit was found to be statistically equivalent (e.g., within 5 MPa) to the first retention strength after impact with 80 grit.

[0183] Example 3

[0184] Table 4 provides a summary of the dual ion exchange (DIOX) conditions for the potassium (K) and sodium (Na) nitrates indicated in Example 3. A substrate of composition A with a thickness of 800 micrometers was used. The DIOX conditions included preheating at 380°C for 10 minutes. Table 4 also shows the following data: compressive stress (CS) after step II, inflection point layer depth (DOL). k ) and central tension (CT). After step I, CS was 540.0 MPa, while DOL k The thickness is 6.50 μm. Both Step I and Step II involve adding 0.5% by weight of silica to the IOX bath. Between Step I and Step II, the substrate is cleaned to remove excess salt.

[0185] Table 4

[0186]

[0187] *Steps I and II each include the addition of 0.5% by weight of silica.

[0188] Figure 7 Provides a smoothed stress distribution curve (stress (MPa) versus depth (micrometers)) for Example 3 following step II. In this example, to account for measurement variability, the stress and depth data are smoothed according to the following equation: y = 9E - 13x 6 -1E-09x 5 +6E-07x 4 -0.0001x 3 +0.0084x 2 -0.0475x+113.15; R 2 =0.9998. Figure 8 for Figure 7 The stress distribution curve is plotted as a graph of the second derivative. Starting from a depth of approximately 50 micrometers, the second derivative remains negative, except for some positive values ​​in the range of 63 to 64 micrometers, until approximately the center of the workpiece (400 micrometers). In the depth range of 50 to 202 micrometers (DOC), the absolute value of the second derivative ranges from 0.03 to 0.70.

[0189] Example 3 was annealed at 500°C after DIOX. Table 5 provides the CT data.

[0190] Table 5

[0191]

[0192] Figure 9 The following is an excerpt of the stress distribution curve for Example 3 after annealing, to demonstrate that the parabolic region conforms to the following equation:

[0193] Stress(x) = 2.317E-03x 2 -2.099E+00x+3.403E+02, where R 2 =9.987E-01.

[0194] Example 5-8

[0195] T on glass substrate g The compositional dependence of (x) and m(x) is based on experimentally determined values ​​and is assessed using modeling derived from equations (1) through (7). For these instances, T g The temperature range is 550℃ to 650℃, and the brittleness index ranges from 25 to 35. f The study was conducted within the following range: 30℃ < T f -T g <70℃. Table 6 provides a summary of the combinations.

[0196] Table 6

[0197]

[0198] Figures 10 to 13 Draw T IOX Stress relaxation rate at 1 hour (IOX temperature) and T f -T g (For example, T) f With T g (Differences between them). The stress relaxation rate of the glass substrate is calculated according to equation (1).

[0199] The desired stress relaxation rate is greater than or equal to 10% (e.g., the range from 20% to 80%, and all values ​​and sub-ranges in between) and the IOX treatment temperature is below 550°C (including below 500°C). Regarding... Figures 11 to 15 For 500℃ T IOX Temperature, T can be determined g Minimum brittleness m m and minimum hypothetical temperature (T) f -T g The correlation between them, such as Figure 15 As shown. For T values ​​less than or equal to 500℃ IOX To achieve the desired stress relaxation, such as based on Figure 15 As shown in Table 7, T can be used at temperatures less than or equal to 650°C. g T at or above 30°C f With T g The difference between (T) f -T g ) and combinations of m greater than or equal to 25.

[0200] Table 7

[0201] Unless otherwise stated, all compositional components, relationships, and ratios described in this specification are provided in mol% (%). Whether expressly stated before or after the disclosure, all scopes disclosed in this specification include any and all scopes and subscopes covered by the broadly disclosed scope.

[0202] While the foregoing describes various embodiments, other and further embodiments of this disclosure can be devised without departing from the basic scope of the invention, the scope of which is determined by the scope of the claims. For example, the features of this disclosure can be combined using any and all combinations, as illustrated in the following embodiments.

[0203] Embodiment 1: A glass substrate comprising: a glass transition temperature (T0) g ), liquid brittleness index (m) and hypothetical temperature (T) f ), where T g Less than or equal to 650℃, T f Subtract T g The value of is greater than or equal to -30℃, and m is greater than or equal to 25.

[0204] Embodiment 2: The glass substrate as described in Embodiment 1 has a stress relaxation rate of 10% or greater.

[0205] Embodiment 3: A glass substrate as described in Embodiment 1 or 2, wherein T gGreater than or equal to 550℃, T f Subtract T g The value is less than or equal to 100℃, and m is greater than or equal to 25.

[0206] Implementation method 4: A glass substrate as described in any of the foregoing embodiments, wherein m is greater than or equal to 30.

[0207] Implementation method 5: A glass substrate as described in any of the foregoing embodiments, wherein m is less than or equal to 60.

[0208] Embodiment 6: The glass substrate as described in Embodiment 1 further comprises: a lithium-based aluminum silicate composition, and a pressure greater than or equal to 0.75 MPa*m. 0.5 Fracture toughness.

[0209] Embodiment 7: The glass substrate as described in Embodiment 6, wherein the lithium-based aluminum silicate composition contains more than 8 mol% of lithium oxide (Li2O).

[0210] Embodiment 8: A glass substrate as described in Embodiment 6, wherein the lithium-based aluminosilicate composition comprises a molar ratio of sodium oxide (Na2O) to lithium oxide (Li2O) of less than 1.0.

[0211] Embodiment 9: The glass substrate as described in the previous embodiment, wherein the molar ratio of sodium oxide (Na2O) to lithium oxide (Li2O) is less than or equal to 0.63.

[0212] Embodiment 10: A glass substrate as described in Embodiment 6, wherein the lithium-based aluminosilicate composition contains potassium oxide (K2O) and phosphorus pentoxide (P2O5) in an amount less than 2 mol% of the composition.

[0213] Embodiment 11: A glass substrate as described in any of Embodiments 6 to the preceding embodiment, wherein the lithium-based aluminosilicate composition comprises: 50 mol% to 69 mol% SiO2; 12.5 mol% to 25 mol% Al2O3; 0 mol% to 8 mol% B2O3; greater than 0 mol% to 4 mol% CaO; greater than 0 mol% to 17.5 mol% MgO; 0.5 mol% to 8 mol% Na2O; 0 mol% to 2.5 mol% La2O3; and greater than 8 mol% to 18 mol% Li2O.

[0214] Embodiment 12: A method for manufacturing a glass-based article, comprising the steps of: preparing a glass composition; processing the glass composition to form a glass substrate, the glass substrate comprising: a glass transition temperature (T0). g ), liquid brittleness index (m) and hypothetical temperature (T) f ), where Tg Less than or equal to 650℃, T f With T g The difference between them is greater than or equal to -30°C, and m is greater than or equal to 25; the glass substrate is placed under ion exchange conditions of less than or equal to 550°C (including less than or equal to 500°C) to form a glass article containing a stress relaxation rate of greater than or equal to 10%.

[0215] Implementation Method 13: The method described in the previous embodiment, wherein the process for forming the glass substrate includes float glass process, pull-down process, fusible forming process, slot drawing process, or roll forming process.

[0216] Implementation method 14: The method described in the previous implementation method further includes an annealing step.

[0217] Those skilled in the art will understand that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Therefore, this disclosure is intended to cover modifications and variations of the various embodiments provided herein that fall within the scope of the appended claims and their equivalents.

Claims

1. An ion exchanged glass-based substrate, wherein the ion exchanged glass-based substrate is formed by subjecting a glass-based substrate to an ion exchange process, the ion exchanged glass-based substrate comprising: a stress relaxation rate greater than 40%; a stress profile that is S-shaped before a depth of compression (DOC) and parabolic after the DOC; and wherein the glass-based substrate prior to ion exchange comprises: Glass transition temperature T g , liquid brittleness index m and fictive temperature T f wherein: T g greater than 550 °C and less than 650 °C, T f Subtracting the value of T g is greater than or equal to 30°C and less than or equal to 70°C, and m greater than or equal to 25.

2. The ion exchanged glass-based substrate of claim 1, wherein the glass-based substrate has a m greater than or equal to 30.

3. The ion exchanged glass-based substrate of claim 1, wherein the glass-based substrate has a m less than or equal to 60.

4. The ion exchanged glass-based substrate of any of claims 1-3, further comprising a lithium-based aluminosilicate composition and having a fracture toughness greater than or equal to 0.75 MPa*m½. 0.5 of claim 1, wherein the glass-based substrate comprises a lithium-based aluminosilicate composition and has a fracture toughness greater than or equal to 0.75 MPa*m½.

5. The ion exchanged glass-based substrate of claim 4, wherein the lithium-based aluminosilicate composition comprises a lithium oxide (Li20) content greater than 8 mol%.

6. The ion exchanged glass-based substrate of claim 4, wherein the lithium-based aluminosilicate composition comprises a molar ratio of sodium oxide (Na20) to lithium oxide (Li20) less than 1.

0.

7. The ion exchanged glass-based substrate of claim 6, wherein the molar ratio of sodium oxide (Na20) to lithium oxide (Li20) is less than or equal to 0.

63.

8. The ion exchanged glass-based substrate of claim 4, wherein the total amount of potassium oxide (K20) and phosphorous pentoxide (P205) in the lithium-based aluminosilicate composition is less than 2 mol% of the composition.

9. The ion exchanged glass-based substrate of claim 4, wherein the lithium-based aluminosilicate composition comprises: 50 to 69 mol% Si02; 12.5 to 25 mol% Al203; 0 to 8 mol% B203; greater than 0 to 4 mol% CaO; greater than 0 to 17.5 mol% MgO; 0.5 to 8 mol% Na20; 0 to 2.5 mol% La203; and greater than 8 to 18 mol% Li20.

10. A method of making an ion exchanged glass-based substrate, comprising the steps of: preparing a glass composition; The glass composition is treated to form a glass-based substrate comprising: a glass transition temperature T g , a liquid fragility index m , and a fictive temperature T f , wherein T g is greater than 550 °C and less than 650 °C, the difference between T f and T g is greater than or equal to 30 °C and less than or equal to 70 °C, and m is greater than or equal to 25; and subjecting the glass-based substrate to an ion exchange condition less than or equal to 550 °C to form the ion exchanged glass-based substrate, the ion exchanged glass-based substrate comprising a stress relaxation rate greater than 40% and a stress profile that is S-shaped before a depth of compression (DOC) and parabolic after the DOC.

11. The method of claim 10, wherein the process used to form the glass-based substrate comprises a float process, a down-draw process, a fusion synthesis forming process, a slot draw process, or a roll forming process.

12. The method of claim 11, further comprising an annealing step.

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