Microcrystalline glass, chemically strengthened microcrystalline glass, cover glass, and electronic equipment

Abstract

This application provides microcrystalline glass, chemically strengthened microcrystalline glass, cover glass, and electronic devices, which belong to the technical field of microcrystalline glass. According to this application, by providing microcrystalline glass with a specific composition and crystalline phase structure, by specifying the content and ratio of each component of the microcrystalline glass within specific ranges, by providing Na2O, BO3, ZrO2, and Li2O in specific mole percent relationships, and by using lithium disilicate as the main crystalline phase of the microcrystalline glass, it is possible to impart excellent optical properties and high intrinsic strength to the microcrystalline glass. Furthermore, by using the microcrystalline glass, it is possible to rapidly and efficiently prepare chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties under conventional chemical strengthening process conditions.

Description

[Technical Field]

[0001] This application relates to the technical field of microcrystalline glass, and more specifically to microcrystalline glass, chemically strengthened microcrystalline glass, cover glass, and electronic equipment.

[0002] Cross-references of related applications This application claims priority based on a Chinese application filed with the China Patent Office on 7 February 2024, application number 202410175049.4, titled "Microcrystalline Glass, Chemically Strengthened Microcrystalline Glass, Cover Glass and Electronic Equipment," all of which are incorporated into this application by reference. [Background technology]

[0003] Microcrystalline glass is a solid composite material produced by controlling crystal precipitation during the heat treatment process of a base glass, and it contains both a microcrystalline phase and a glass phase. Compared to glass materials that do not contain a microcrystalline phase, microcrystalline glass generally has higher strength. This is because the microcrystalline phase, which has higher strength than the glass phase, can absorb more energy during fracture. Furthermore, the microcrystalline phase can extend the crack propagation path and prevent crack expansion, thus allowing more impact energy to be dissipated during the fracture process.

[0004] In recent years, microcrystalline glass has been gradually applied to various electronic devices such as mobile phones, watches, tablets, laptops, e-readers, and other similar devices as cover glass for electronic devices, including display cover glass and back cover glass. Display cover glass for electronic devices generally requires good optical properties, as well as thinness and high mechanical properties. To further improve the mechanical properties of microcrystalline glass, it is usually necessary to perform chemical strengthening treatment. By performing ion exchange, chemically strengthened microcrystalline glass with high stress levels, high mechanical strength, and high damage resistance can be produced.

[0005] Therefore, how to improve the chemical strengthening effect of microcrystalline glass while satisfying excellent optical properties, or how to achieve the rapid and efficient preparation of chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties, are technical problems that those skilled in the art should solve as soon as possible. [Overview of the project]

[0006] The difficulty of chemical strengthening differs depending on the structure of microcrystalline glass and glass materials that do not contain a microcrystalline phase. To prepare high-strength chemically strengthened microcrystalline glass that has high stress levels and high mechanical strength properties and meets the requirements of optical properties applications for cover glasses, those skilled in the art typically perform long chemical strengthening treatments or chemical strengthening treatments using high-temperature (e.g., above 480°C) molten salts compared to conventional microcrystalline glass. However, extending the strengthening time or increasing the molten salt temperature leads to an increase in the cost of chemical strengthening microcrystalline glass, and thus an increase in the manufacturing cost of high-strength chemically strengthened microcrystalline glass.

[0007] Therefore, this application aims to provide microcrystalline glass having excellent optical properties and high intrinsic strength by adjusting the composition and structure of the microcrystalline glass. With this microcrystalline glass, chemically strengthened microcrystalline glass with high stress levels, excellent mechanical strength properties and damage resistance can be prepared quickly and efficiently under normal chemical strengthening process conditions.

[0008] To achieve the above objective, this application provides the following technical solution.

[0009] In the first phase, a microcrystalline glass is provided, wherein the microcrystalline glass contains a lithium disilicate (lithium disilicate) crystalline phase having a higher weight percentage than other crystalline phases present in the microcrystalline glass, and the components of the microcrystalline glass are expressed in mol% on an oxide basis as follows: SiO2: 61.50%~63.40%, Al2O3: 2.75%~2.99%, P2O5: 0.91%~1% The composition of the microcrystalline glass includes 0.91%, ZrO2: 4.20%~4.85%, Na2O: 1.80%~3.20%, B2O3: 0~1.00%, and Li2O: 25.32%~26.52%. In the composition of the microcrystalline glass, the molar percentage of Na2O [Na2O], the molar percentage of B2O3 [B2O3], and the molar percentage of ZrO2 [ZrO2] is given by Z = -1.344 × (2.65 - 100 × [Na2O]). 2 The formula is +0.466 × 100 × [B2O3] + 1.203 × 100 × [ZrO2], satisfying the relationship 4.80 ≤ Z ≤ 5.35, preferably 4.98 ≤ Z ≤ 5.20.

[0010] By giving microcrystalline glass a specific composition and crystal phase structure, setting the content and mixing ratio of each component within a specific range, and establishing specific molar percentage relationships for Na2O, B2O3, ZrO2, and Li2O, and making lithium disilicate the main crystal phase of the microcrystalline glass, it is possible to impart excellent optical properties and high intrinsic strength to the microcrystalline glass. Furthermore, under normal chemical strengthening process conditions, it is possible to rapidly and efficiently prepare chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties using microcrystalline glass.

[0011] In some embodiments, the composition of the microcrystalline glass satisfies the relationship between the molar percentage of Na2O [Na2O] and the molar percentage of B2O3 [B2O3]: 0.90% ≤ [Na2O] - [B2O3] ≤ 3.10%, preferably 1.25% ≤ [Na2O] - [B2O3] ≤ 3.02%, and more preferably 2.00% ≤ [Na2O] - [B2O3] ≤ 3.00%.

[0012] In some embodiments, in the composition of the microcrystalline glass, the molar % of Na2O [Na2O] and the molar % of Li2O [Li2O] satisfy the relationship of 8.55 ≤ [Li2O] / [Na2O] ≤ 13.85, preferably 8.55 ≤ [Li2O] / [Na2O] ≤ 11.50.

[0013] In some embodiments, in all crystal phases of the microcrystalline glass, the weight % of the lithium disilicate crystal phase is 70% or more, preferably 85% or more.

[0014] In some embodiments, in terms of molar % based on oxides, the microcrystalline glass has a molar % of SiO2 of 61.50% to 63.30%, preferably 62.00% to 62.60%, and / or a molar % of P2O5 of 1.20% to 1.91%, preferably 1.30% to 1.60%, and / or a molar % of Na2O of 1.85% to 3.05%, preferably 2.20% to 3.00%, and / or a molar % of B2O3 of 0 to 0.65%, and / or a molar % of ZrO2 of 4.20% to 4.80%, and / or a molar % of Li2O of 25.52% to 26.52%, preferably 25.52% to 26.00%.

[0015] In some embodiments, the microcrystalline glass, in terms of mol% based on oxides, has a SiO2 mol% of 62.88%, 63.30%, 62.50%, 63.26%, 62.38%, 62.27%, 62.45%, 62.22%, or 63.17%, and / or an Al2O3 mol% of 2.86%, 2.87%, 2.93%, 2.94%, or 2.99%, and / or a P2O5 mol% of 1.00%, 1.20%, 1.30%, 1.60%, 1.40%, 1.41%, 1.53%, or 1.54%, and / or a ZrO2 mol% of 4.80%, 4.74%, 4.84%, 4.33%, 4.34%, or 4.35%, and / or a Na2O mol% of 1.85%, 2.35%, 1.95%, 2.36%, 2.96%, 3.01%, 2.93%, or 2.95%, and / or a Li2O mol% of 25.62%, 25.82%, 25.69%, 25.36%, 25.77%, 25.87%, 25.90%, 25.79%, 26.03%, or 25.74%.

[0016] In some embodiments, the composition of the microcrystalline glass, in terms of the molar% content of oxides, has a value of formula Z of 5.19, 5.10, 5.09, 5.06, or 5.13, and / or a value of [Na2O] - [B2O3] of 1.26%, 1.79%, 0.96%, 2.36%, 2.96%, 3.01%, 2.93%, or 2.95%, and / or a value of [Li2O] / [Na2O] of 13.83, 10.93, 13.01, 10.92, 8.73, 8.61, 8.79, or 8.83.

[0017] In some embodiments, the crystallinity of the microcrystalline glass is 45% or more, preferably 45% - 85%, more preferably 55% - 65%, and / or in the microcrystalline glass, the average crystal grain size is 100 nm or less, preferably 40 nm or less, more preferably 15 - 30 nm.

[0018] In some embodiments, the microcrystalline glass is transparent in the visible light wavelength range, preferably with a thickness of 0.70 mm, and the transmittance of the microcrystalline glass for light at a wavelength of 550 nm is 90.00% or more, preferably more than 90.40%, and / or the haze of the microcrystalline glass is less than 0.30% with a thickness of 0.70 mm.

[0019] In some embodiments, the thickness is 0.70 mm, and the b value of the microcrystalline glass is less than 0.70, preferably 0.60 or less.

[0020] In some embodiments, the Young's modulus of the microcrystalline glass is 100 GPa or higher, preferably 105 to 112.50 GPa, and / or the Vickers hardness of the microcrystalline glass is 640 kgf / mm². 2 Preferably, 640-680 kgf / mm² 2 That is the case.

[0021] In some embodiments, the microcrystalline glass includes planar microcrystalline glass or curved microcrystalline glass, and preferably, when the microcrystalline glass is curved microcrystalline glass, the microcrystalline glass can be prepared by subjecting a crystallized glass material with a crystallinity of 5% or more to a three-dimensional hot bending process.

[0022] In some embodiments, the microcrystalline glass is prepared by heat-treating a base glass, preferably the heat treatment step includes a nucleation treatment and / or a crystallization treatment, preferably the crystallization treatment includes a one-stage crystallization treatment or a two-stage crystallization treatment, and preferably, when preparing curved microcrystalline glass by a two-stage crystallization treatment, the second crystallization treatment step involves heating the crystallized glass material obtained in the first crystallization treatment step to a crystallization temperature and performing a three-dimensional hot bending and forming treatment, and performing secondary crystallization during the three-dimensional hot bending and forming process.

[0023] In some embodiments, the thickness of the microcrystalline glass is 0.10 to 5.00 mm.

[0024] In the second phase, a chemically strengthened microcrystalline glass is provided, which is prepared by a chemical strengthening treatment from the microcrystalline glass described in any embodiment of the first phase. The composition of the central part of the chemically strengthened microcrystalline glass is the same as the composition of the microcrystalline glass described in any embodiment of the first phase, and it includes a compressive stress layer region extending from the surface to the compression depth and has tensile stress internally. That is, the chemically strengthened microcrystalline glass includes a compressive stress layer and a tensile stress layer.

[0025] In some embodiments, the chemically strengthened microcrystalline glass contains a lithium disilicate crystalline phase having a higher weight percentage than other crystalline phases present in the chemically strengthened microcrystalline glass, and the central components of the chemically strengthened microcrystalline glass are, in molar percentages based on oxide, SiO2: 61.50%~63.40%, Al2O3: 2.75%~2.99%, and P2O5: 0.91%~1.91%. The composition of the chemically strengthened microcrystalline glass in the center of the glass is as follows: ZrO2: 4.20%~4.85%, Na2O: 1.80%~3.20%, B2O3: 0~1.00%, Li2O: 25.32%~26.52%, where Z = -1.344 × (2.65 - 100 × [Na2O]) 2 The formula is +0.466 × 100 × [B2O3] + 1.203 × 100 × [ZrO2], satisfying the relationship 4.80 ≤ Z ≤ 5.35, preferably 4.98 ≤ Z ≤ 5.20.

[0026] In some embodiments, in the composition of the center of the chemically strengthened microcrystalline glass, the molar %[Na2O] of Na2O and the molar %[B2O3] of B2O3 satisfy the relationship 0.90%≦[Na2O]-[B2O3]≦3.10%, preferably 1.25%≦[Na2O]-[B2O3]≦3.02%, more preferably 2.00%≦[Na2O]-[B2O3]≦3.00%, and / or, in the composition of the center of the chemically strengthened microcrystalline glass, the molar %[Na2O] of Na2O and the molar %[Li2O] of Li2O satisfy the relationship 8.55≦[Li2O] / [Na2O]≦13.85, preferably 8.55≦[Li2O] / [Na2O]≦11.50.

[0027] In some embodiments, the chemically strengthened microcrystalline glass has a CT_LD of 45,000 to 55,000 MPa / mm, preferably 48,000 to 53,000 MPa / mm, where CT_LD is the tensile stress linear density, and / or the chemically strengthened microcrystalline glass has a DOL_0 of 0.18t to 0.25t, preferably 0.20t to 0.25t, where DOL_0 is the compressive stress layer depth and t is the thickness of the chemically strengthened microcrystalline glass, and / or the chemically strengthened microcrystalline glass has a thickness of 150 to 19 The chemically strengthened microcrystalline glass has a CS_50 of 9 MPa, preferably a CS_50 of 160 to 199 MPa, where CS_50 is the compressive stress value at a depth of 50 μm from the main surface of the chemically strengthened microcrystalline glass, and / or the chemically strengthened microcrystalline glass has a |CT_AV| of 80 to 98 MPa, where |CT_AV| is the absolute value of the average tensile stress, and / or the chemically strengthened microcrystalline glass has a |CT_CV| of 115 to 142 MPa, preferably a |CT_CV| of 120 to 140 MPa, where |CT_CV| is the absolute value of the maximum tensile stress.

[0028] In some embodiments, the Vickers hardness of the chemically strengthened microcrystalline glass is 680 kgf / mm². 2 Preferably, 700 kgf / mm² 2 ~800 kgf / mm 2 That is the case.

[0029] In the third phase, a glass member is provided, the glass member comprising a microcrystalline glass described in any embodiment of the first phase or a chemically strengthened microcrystalline glass described in any embodiment of the second phase.

[0030] In the fourth phase, a cover glass is provided, which is prepared using microcrystalline glass described in any embodiment of the first phase or chemically strengthened microcrystalline glass described in any embodiment of the second phase. That is, the cover glass includes microcrystalline glass described in any embodiment of the first phase or chemically strengthened microcrystalline glass described in any embodiment of the second phase. The cover glass may be a display cover, a back cover, or a camera protective cover for an electronic device.

[0031] In the fifth phase, an electronic device is provided, the electronic device comprising a microcrystalline glass described in any embodiment of the first phase or a chemically strengthened microcrystalline glass described in any embodiment of the second phase.

[0032] In some embodiments, the electronic device includes a housing mounted on the outside of the electronic device and a circuit board housed inside the housing, wherein the housing includes microcrystalline glass as described in any of the embodiments of the first aspect or chemically strengthened microcrystalline glass as described in any of the embodiments of the second aspect.

[0033] In some embodiments, the housing includes a display cover mounted on the front of the electronic device, the display cover including microcrystalline glass as described in any of the embodiments of the first aspect or chemically strengthened microcrystalline glass as described in any of the embodiments of the second aspect.

[0034] In some embodiments, the housing includes a back cover that is attached to the back of the electronic device, the back cover comprising microcrystalline glass as described in any of the embodiments of the first aspect or chemically strengthened microcrystalline glass as described in any of the embodiments of the second aspect.

[0035] In some embodiments, the electronic device further includes a camera element housed inside the housing, the housing includes a camera protective cover provided for the camera element, and the camera protective cover includes microcrystalline glass as described in any of the embodiments of the first aspect or chemically strengthened microcrystalline glass as described in any of the embodiments of the second aspect.

[0036] In some embodiments, the electronic device further includes an intermediate frame positioned between the display module and the housing, wherein the intermediate frame comprises microcrystalline glass as described in any of the embodiments of the first aspect or chemically strengthened microcrystalline glass as described in any of the embodiments of the second aspect.

[0037] In some embodiments, the housing may be made of microcrystalline glass or chemically strengthened microcrystalline glass in part or in whole. In the electronic device according to this application, the display cover, back cover, camera protective cover, and part of the intermediate frame may be made of microcrystalline glass as described in any of the embodiments of the first aspect or chemically strengthened microcrystalline glass as described in any of the embodiments of the second aspect.

[0038] One or more of the above-mentioned technical solutions provided in this application have the following advantages:

[0039] According to this application, by giving microcrystalline glass a specific composition and crystal phase structure, setting the content and blending ratio of each component within a specific range, setting the molar percentages of Na2O, B2O3, ZrO2, and Li2O, and making lithium disilicate the main crystal phase of the microcrystalline glass, it is possible to impart excellent optical properties and high intrinsic strength to the microcrystalline glass. Furthermore, it is possible to rapidly and efficiently prepare chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties under normal chemical strengthening process conditions using microcrystalline glass. Therefore, the manufacturing cost of high-strength chemically strengthened microcrystalline glass can be effectively reduced.

[0040] To more clearly explain the technical concepts of the embodiments in this application, the drawings necessary for describing the embodiments are briefly described below. The drawings described are only a selection of embodiments of this application and do not limit the scope. A person skilled in the art can obtain other relevant drawings based on these drawings without employing inventive ability. [Brief explanation of the drawing]

[0041] [Figure 1] This is the XRD pattern of the microcrystalline glass according to Example 2. [Figure 2] This is the transmittance curve of the microcrystalline glass according to Example 2 in the 360nm to 740nm band. [Figure 3] This is a comparison diagram of the XRD patterns of the microcrystalline glass before and after chemical strengthening according to Example 2. [Figure 4] This is an actual image of the microcrystalline glass according to Example 2. [Figure 5] This is an actual image of the microcrystalline glass according to Example 7. [Figure 6] This is an actual image of the microcrystalline glass related to Comparative Example 5. [Figure 7] This is an actual image of the microcrystalline glass related to Comparative Example 6. [Figure 8] This is an actual image of the microcrystalline glass related to Comparative Example 8. [Figure 9] This is a schematic front view of an electronic device according to an embodiment of this application. [Figure 10] This is a schematic diagram of the rear view of an electronic device according to an embodiment of this application. [Figure 11] This is a schematic diagram of the electronic device according to the embodiment of this application. [Modes for carrying out the invention]

[0042] The technical proposal of this application will be described in detail below using examples, but these examples are merely for illustrative purposes and should not be considered to limit the scope of this application. In the examples, specific conditions are not specified, but it is possible to perform the work under conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, it is possible to use commercially available conventional products.

[0043] The endpoints of the ranges and any values ​​disclosed herein are not limited to exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, one or more new numerical ranges can be obtained by combining the endpoints of each range, the endpoints of each range with a single point, or the points with a single point, and these numerical ranges should also be considered specifically disclosed herein. The terms “any” and “any of” mean “may or may not be included.” “And / or” as used herein is inclusive; for example, “A and / or B” means that only A exists, or only B exists, or both A and B exist.

[0044] The terms and measurement methods are explained below.

[0045] In this application, microcrystalline glass is a solid composite material containing both a glass phase and a crystalline phase (also called a microcrystalline phase), and is also called glass ceramic or crystallized glass.

[0046] In this application, chemically strengthened microcrystalline glass is a solid composite material obtained by subjecting microcrystalline glass to a chemical strengthening treatment. During the chemical strengthening treatment, alkali metal ions with small ionic radii (e.g., sodium ions and lithium ions) in the microcrystalline glass are replaced with alkali metal ions with large ionic radii (e.g., potassium ions and sodium ions) in the molten salt, thereby creating a volume difference between the exchanged ions and generating compressive stress on the surface layer of the microcrystalline glass.

[0047] In this application, the base glass is glass that has not undergone nucleation treatment, crystallization treatment, or strengthening treatment, and is also called raw glass.

[0048] In this application, the composition of the central part of the chemically strengthened microcrystalline glass is the composition of the central part or its vicinity in terms of depth and thickness, that is, the composition of the region in the chemically strengthened microcrystalline glass where ion exchange does not occur. Furthermore, the composition of the central part of the chemically strengthened microcrystalline glass is the same as or substantially the same as the composition of the unstrengthened microcrystalline glass used to prepare this chemically strengthened microcrystalline glass.

[0049] In this application, the visible light wavelength range is 360 nm to 740 nm.

[0050] In this application, haze is defined as the percentage of transmitted light that is shifted by 2.5° or more from the incident light.

[0051] In this application, the primary crystalline phase is a crystalline phase having a higher weight content (also called weight percentage or mass percentage) than other crystalline phases present in the microcrystalline glass.

[0052] In this application, the main surface is the surface having the largest surface area in the glass block or glass sheet, for example, the upper or lower surface of a horizontally arranged microcrystalline glass sheet.

[0053] In this application, the degree of crystallinity is the percentage of the total mass of the crystalline phase or crystals in the microcrystalline glass relative to the mass of the microcrystalline glass, and is also called the total content of the crystalline phase in the microcrystalline glass.

[0054] In this application, when light of a wavelength present on the main surface of a microcrystalline glass is irradiated, the light is reflected, absorbed, or transmitted. Transmittance is the ratio of the intensity of the transmitted portion to the intensity of the incident light.

[0055] In this application, the D65 light source has a color temperature of 6500K, a color rendering index Ra higher than 90, and is a light source for measuring the color of an object by irradiating it with daylight including the ultraviolet region, and exhibits a broad spectral distribution in the visible light wavelength region.

[0056] In this application, the crystallized glass material is a glass material that has undergone heat treatment for a certain period of time, which has reached a certain degree of crystallinity but has not reached the target degree of crystallinity, and can continue to crystallize and reach the target degree of crystallinity when heat is applied.

[0057] In this application, CT_LD is the tensile stress linear density, with units of MPa / mm. Furthermore, after ion exchange of microcrystalline glass with a molten salt, a compressive stress layer is formed on the surface of the microcrystalline glass, and a tensile stress layer is formed inside the microcrystalline glass. Exemplarily, during chemical strengthening treatment, by replacing small-radius alkali metal ions in the microcrystalline glass with large-radius alkali metal ions in the molten salt, a compressive stress layer is formed on the surface of the microcrystalline glass, and a tensile stress layer is formed inside the microcrystalline glass. That is, chemically strengthened microcrystalline glass containing a compressive stress layer and a tensile stress layer is prepared. In this application, CT_LD is calculated by the following formula.

[0058]

number

[0059] Here, t is the thickness of the chemically strengthened microcrystalline glass in mm, DOL_0 is the depth of the compressive stress layer of the chemically strengthened microcrystalline glass in μm, and |CT_AV| is the absolute value of the average tensile stress of the chemically strengthened microcrystalline glass in MPa. Furthermore, in the calculation formula for tensile stress linear density, the values ​​are substituted according to the above unit requirements to obtain the calculation result, but the units do not affect the calculation.

[0060] In this application, CS_50 is the compressive stress value at a depth of 50 μm from the main surface of the chemically strengthened microcrystalline glass, in units of MPa. It is measured using an SLP-2000 stress meter.

[0061] In this application, |CT_AV| is the absolute value of the average tensile stress, in units of MPa, and specifically, the absolute value of the average value of all tensile stresses in the tensile stress layer. It is measured by an SLP-2000 stress meter.

[0062] In this application, |CT_CV| is the absolute value of the maximum tensile stress, in units of MPa, and specifically, the absolute value of the maximum tensile stress in the tensile stress layer. It is measured by an SLP-2000 stress meter.

[0063] In this application, DOL_0 is the depth of the compressive stress layer, specifically the distance from any main surface of the chemically strengthened microcrystalline glass to the point where the compressive stress approaches this surface and becomes zero. This is measured by an SLP-2000 stress meter.

[0064] In this application, the above-mentioned stress properties are measured using an SLP-2000 stress meter to measure |CT_CV|, DOL_0, and |CT_AV| of the chemically strengthened microcrystalline glass. The relevant parameters of the stress meter are set as follows: the wavelength of the light source is 518 nm, the SOC (photoelastic coefficient) is 26 [(nm / cm) / MPa], the refractive index is 1.56, and the exposure time is 300 μsec. The value of the tensile stress linear density (CT_LD) of the chemically strengthened microcrystalline glass is then calculated using the above-mentioned formula for calculating tensile stress linear density.

[0065] In this application, the b-value represents the blue and yellow values ​​of the material. The b-value in this application is the b-value of transmitted light, and a positive b-value indicates that the material is bluish.

[0066] In this application, Vickers hardness is a measure of material hardness devised in 1921 by Robert L. Smith and George E. Sandland of Vickers Ltd. in the United Kingdom.

[0067] In this application, the method for measuring Vickers hardness is as follows: A sheet of microcrystalline glass or chemically strengthened microcrystalline glass measuring 50 mm in length, 50 mm in width, and 0.70 mm in thickness is selected as the test sample. The glass sample is clean on the surface and free from visible damage such as scratches, dents, or cracks, and the Vickers hardness is measured using a Vickers hardness tester. The Vickers hardness tester used in the tests in this application is a digital display small-load Vickers hardness tester, model number VTD405, manufactured by Beijing Kewei Technology Co., Ltd. The test conditions are a load of 300 gf, a loading time of 10 s, and the effectiveness of the indentation conforms to the standards of "GB / T37900-2019 Small-load Vickers hardness indentation method according to the method for measuring the hardness and fracture toughness of ultrathin glass". Three different measurement positions are selected on the surface of one test sample and measurements are taken. The average of the three measurement results is recorded as the Vickers hardness of the test sample.

[0068] In this application, Young's modulus represents the resistance of glass to elastic deformation due to external forces. In this application, the Young's modulus of microcrystalline glass is measured ultrasonically using the UMS-100 ultrasonic material characterization system.

[0069] In this application, nucleation treatment refers to the process of forming small crystal nuclei from nucleating material in a substrate glass by heat treatment. Crystallization treatment refers to the process of precipitating specific crystals or target crystals from a glass substrate by heat treatment.

[0070] In this application, the thickness of the microcrystalline glass is measured by a micrometer. Furthermore, when ion exchange is performed, the overall increase in mass due to Na-K and / or Li-Na ion exchange is generally less than 1.5% of the total sample mass. Therefore, the expansion effect in the thickness direction is extremely small, and it is approximated that the thickness hardly changes. In other words, the change in the thickness of the microcrystalline glass before and after chemical strengthening is negligibly small, and the thickness of the microcrystalline glass is approximately the same as the thickness of the prepared chemically strengthened microcrystalline glass.

[0071] In this application, the size of the microcrystalline glass sheet is measured by a two-dimensional measuring machine (model number MiyuMY-YXCL-4030).

[0072] In this application, the crystalline phase, crystallinity, and average grain size of the microcrystalline glass or chemically strengthened microcrystalline glass were measured by XRD and are specifically as follows:

[0073] (1) XRD test: Microcrystalline glass or chemically strengthened microcrystalline glass relating to this application was crushed and polished into samples with a particle size of less than 75 μm. The obtained samples were measured using an X-ray diffractometer to obtain XRD diffraction peak curves and XRD diffraction data. The X-ray diffractometer used in this application was a Shimadzu XRD-6100, with a copper metal target, a scanning speed of 6° / min, an operating voltage of 40kV, an operating current of 30mA, and 2θ = 10°-50°.

[0074] (2) Confirmation of crystalline phase: XRD diffraction data was analyzed using the software Jade (JADE Standard 8.6) to confirm the crystalline phase in the sample.

[0075] (3) Confirmation of crystallinity (also called total crystalline phase content): The XRD test results (RAW format) were imported into Jade, Rietveld analysis software for X-ray diffraction data, and fitting and calculations were performed to confirm the crystallinity of the sample. Specifically, the ratio of the fitted crystalline phase peak area to the fitted total peak area was defined as the crystallinity of the sample.

[0076] (4) Confirmation of average crystal grain size (also called average crystal size): Using the data obtained from the XRD test, the average crystal grain size of the sample can be calculated according to Scherrer's equation D = Kλ / (βcosθ). Here, λ is the X-ray wavelength, λ = 0.154056 nm, β is the full width at half maximum of the diffraction peak, K = 0.89, and θ is the Bragg angle. Specifically, the RAW file output from the XRD instrument was curve-fitted using the Jade software, and based on the angle 2θ value and Peak FWHM value corresponding to each diffraction peak in the fitting results output from Jade, the Peak FWHM value was converted to radians, resulting in β = (FWHM / 180 × 3.14). Then, the crystal size of each diffraction peak was calculated using Scherrer's equation D = Kλ / (βcosθ) and averaged to obtain the average crystal grain size of the sample.

[0077] In this application, the transmittance, haze, and b-value of the microcrystalline glass relating to this application were measured using a haze meter, referring to the national standard "GB / T7962.12-2010 Method for Measuring Colorless Optical Glass Part 12: Spectral Transmittance". Specifically, the transmittance, haze, and b-value of five microcrystalline glass pieces from the same lot for different wavelengths of light were measured using a haze meter, and the average values ​​of the b-value and haze of the five microcrystalline glass pieces were taken as the b-value and haze of the microcrystalline glass, respectively. The average value of the transmittance of the five microcrystalline glass pieces at a wavelength of 550 nm was taken as the transmittance of the microcrystalline glass at a wavelength of 550 nm. The haze meter used in the tests described in this application is a Konica Minolta CM-3600A spectrophotometer, with a transmissive light-receiving optical system, a planar diffraction grating as the spectral means, a wavelength range of 360 nm to 740 nm, a wavelength interval of 10 nm, four pulsed xenon lamps as the illumination light source, an ambient temperature of 24°C, and an air humidity of 40%.

[0078] In this application, for multiple chemically strengthened microcrystalline glass samples relating to the same embodiment or comparative example, the drop heights of the sandpaper drop test for each sample were added together, and the sum of these values ​​was divided by the number of samples to determine the average drop height of the chemically strengthened microcrystalline glass in the sandpaper drop test. This average drop height represents the drop resistance of the chemically strengthened microcrystalline glass. Specifically, at least 10 samples were measured from each lot, and the average drop height was calculated.

[0079]

number

[0080] The following was calculated: where n is the number of glass samples tested in each lot, and hi is the drop height of the sandpaper drop test for a single sample.

[0081] The method for measuring the drop height in a single-sample sandpaper drop test is as follows:

[0082] Step 1: Attach 80-mesh sandpaper to the underside of the 181g model machine, and then place the model machine on the LT-SKDL-CD type drop device manufactured by Midorizu Co., Ltd.

[0083] Step 2: Place the chemically strengthened microcrystalline glass sample to be tested directly beneath the model machine so that it faces the sandpaper. Specifically, ensure that the main surface of the chemically strengthened microcrystalline glass faces the sandpaper. Drop the model machine from a certain height, causing it to collide with the chemically strengthened microcrystalline glass sample directly beneath it. If no cracks appear in the chemically strengthened microcrystalline glass sample, increase the drop height of the model machine to a certain extent and continue dropping the model machine, causing it to collide with the chemically strengthened microcrystalline glass sample directly beneath it, until the chemically strengthened microcrystalline glass sample is destroyed. For example, drop the model machine from a height of 0.4m, collide it with the sample once, and if no cracks appear in the sample, increase the drop height by 0.1m and drop the model machine again, repeating the above process until the chemically strengthened microcrystalline glass sample is destroyed.

[0084] Step 3: Record the drop height just before the chemically strengthened microcrystalline glass sample breaks as the drop height for that sandpaper drop test. For example, if the drop height is increased by 0.1m increments, and the sample breaks at a drop height of 0.5m, the drop height for that sandpaper drop test would be 0.4m.

[0085] While not bound by any particular theory, it is presumed that when microcrystalline glass is subjected to chemical strengthening, ion exchange primarily occurs between alkali metal ions in the glass phase and alkali metal ions in the molten salt, forming a compressive stress structure on the surface of the microcrystalline glass, thereby further improving the mechanical strength properties and damage resistance of the microcrystalline glass. The dense crystalline structure contained in microcrystalline glass contributes to the improvement of its intrinsic strength and damage resistance, but the interconnected structure formed by the dense crystalline particles in the microcrystalline glass encapsulates the glass phase (also called the residual glass phase) between the crystalline particles, thus hindering the ion exchange pathway and inhibiting ion exchange between alkali metal ions in the glass phase and alkali metal ions in the chemical strengthening molten salt. Therefore, it becomes difficult to obtain high stress properties through chemical strengthening of microcrystalline glass, that is, it becomes difficult to prepare high-strength chemically strengthened microcrystalline glass. In particular, lithium aluminosilicate glass is prone to the precipitation of non-uniform crystalline phases such as lithium disilicate crystalline phase, quartz crystalline phase, and lithium metasilicate crystalline phase after heat treatment. Microcrystalline glasses with non-uniform crystalline phases exhibit high crystallinity, but the higher the crystal content, the greater the energy and time required for ion diffusion. Therefore, structures with non-uniform crystalline phases may further increase the difficulty of ion exchange in microcrystalline glasses.

[0086] In conventional techniques, to prepare chemically strengthened microcrystalline glass that meets the requirements of use, conventional microcrystalline glass is typically subjected to long chemical strengthening treatments or chemical strengthening treatments using molten salts at high temperatures (e.g., above 480°C). However, extending the strengthening time or increasing the temperature of the strengthening molten salt leads to an increase in the cost of chemical strengthening the microcrystalline glass, and thus an increase in the manufacturing cost of high-strength chemically strengthened microcrystalline glass.

[0087] In view of the above, this application provides, in order to improve economic efficiency, a microcrystalline glass that differs from the prior art, possesses excellent optical properties and high intrinsic strength, and allows for rapid ion exchange to obtain a high stress level. According to the microcrystalline glass of this application, chemically strengthened microcrystalline glass with a high stress level, excellent mechanical strength properties and damage resistance can be prepared quickly and efficiently under normal chemical strengthening process conditions.

[0088] As described above, in some embodiments of this application, microcrystalline glass is provided. The microcrystalline glass contains a lithium disilicate crystalline phase (Li2Si2O5) having a higher weight percentage than other crystalline phases present in the microcrystalline glass. The components of the microcrystalline glass include, in molar percentages based on oxides, SiO2: 61.50%~63.40%, Al2O3: 2.75%~2.99%, P2O5: 0.91%~1.91%, ZrO2: 4.20%~4.85%, Na2O: 1.85%~3.20%, B2O3: 0~1.00%, and Li2O: 25.32%~26.52%.

[0089] In the composition of the aforementioned microcrystalline glass, the molar percentages of Na2O [Na2O], B2O3 [B2O3], and ZrO2 [ZrO2] are given by Z = -1.344 × (2.65 - 100 × [Na2O]). 2 The formula is +0.466 × 100 × [B2O3] + 1.203 × 100 × [ZrO2], satisfying the relationship 4.80 ≤ Z ≤ 5.35, preferably 4.98 ≤ Z ≤ 5.20.

[0090] The lithium disilicate (Li2Si2O5) crystalline phase is orthorhombic, based on a [Si2O5] tetrahedral array, and exhibits a flattened or plate-like crystal shape. Within the microcrystalline glass, the lithium disilicate crystals have a microstructure of randomly oriented interlocking crystals, which twists the crack propagation path and prevents crack expansion. Therefore, the strength and fracture toughness of the microcrystalline glass can be improved. Furthermore, the lithium disilicate crystals have a refractive index close to that of the glass substrate (for example, the substrate glass used to prepare the microcrystalline glass according to this application), making them an ideal crystalline phase for preparing highly transparent microcrystalline glass. In this application, the microcrystalline glass includes a structure with lithium disilicate as the main crystalline phase, contributing to the acquisition of high intrinsic strength and excellent optical properties.

[0091] According to this application, by giving microcrystalline glass a specific composition and crystal phase structure, setting the content and blending ratio of each component within a specific range, setting the molar percentages of Na2O, B2O3, ZrO2, and Li2O, and making lithium disilicate the main crystal phase of the microcrystalline glass, it is possible to impart excellent optical properties and high intrinsic strength to the microcrystalline glass. Furthermore, under the conditions of a normal chemical strengthening process, chemically strengthened microcrystalline glass with high stress levels and high mechanical strength can be prepared rapidly and efficiently from the microcrystalline glass. Therefore, the manufacturing cost of high-strength chemically strengthened microcrystalline glass can be effectively reduced.

[0092] The microcrystalline glass according to this application can be prepared from a base glass by heat treatment. The composition of the microcrystalline glass, expressed in mol% based on oxides, is the same as or substantially the same as the composition of the base glass used.

[0093] In this application, SiO2 is an essential component necessary for forming the network structure of the glass and is one of the main components for forming lithium disilicate crystals. The higher the SiO2 content, the denser the network structure of the glass phase becomes, which in turn increases the mechanical strength of the microcrystalline glass, reduces the coefficient of thermal expansion, and improves heat resistance, dielectric properties, and chemical stability. However, if the SiO2 content is too high, the melting temperature of the base glass increases, the melt viscosity increases, and the base glass becomes difficult to mold. Therefore, in this application, in order to achieve both the moldability of the glass and excellent properties, the molar percentage of SiO2 in the base glass or microcrystalline glass is 61.50% to 63.40%, preferably 61.50% to 63.30%, and more preferably 62.00% to 62.60%.

[0094] In some embodiments of this application, the SiO2 content in the substrate glass or microcrystalline glass, expressed in molar percentages based on oxide, is 62.87%, 62.88%, 63.25%, 63.26%, 62.38%, 62.27%, 62.44%, 62.45%, 62.22%, 63.17%, 61.50%, 61.60%, 61.70%, 61.80%, 61.90%, 62.00%, 62.10%, 62.20%. The values ​​may be %, 62.30%, 62.40%, 62.50%, 62.60%, 62.70%, 62.80%, 62.90%, 63.00%, 63.10%, 63.20%, 63.30%, or 63.40%, or any value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0095] In this application, Al2O3 is a component necessary for forming the network structure of the glass. An appropriate amount of Al2O3 contributes to improving the chemical strengthening effect of microcrystalline glass and promotes ion exchange in the chemical strengthening process to some extent. However, excess Al2O3 leads to an increase in the viscosity of the glass and easily causes the precipitation of other crystalline phases such as petalite, affecting the crystalline phase structure of the microcrystalline glass. Therefore, in order to obtain the desired crystalline phase structure and improve the chemical strengthening effect of the microcrystalline glass, the molar percentage of Al2O3 in the base glass or microcrystalline glass in this application is 2.75% to 2.99%.

[0096] In some embodiments of this application, the Al2O3 content in the substrate glass or microcrystalline glass, expressed in mol% on an oxide basis, may be 2.75%, 2.77%, 2.79%, 2.81%, 2.83%, 2.85%, 2.86%, 2.87%, 2.89%, 2.91%, 2.93%, 2.94%, 2.95%, 2.97%, or 2.99%, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0097] In this application, P2O5 acts as a nucleating agent to promote the uniform formation of crystal nuclei in the glass. If its content is too low or too high, the crystallinity deteriorates, affecting the optical properties of the resulting microcrystalline glass and leading to a decrease in the transparency of the microcrystalline glass. Therefore, in order to obtain the desired crystalline phase structure and achieve excellent optical and mechanical strength properties, in this application, the molar percentage of P2O5 in the substrate glass or microcrystalline glass is 0.91% to 1.91%, preferably 1.20% to 1.91%, and more preferably 1.30% to 1.60%.

[0098] In some embodiments of this application, the P2O5 content in the substrate glass or microcrystalline glass, expressed in mol% on an oxide basis, may be 0.91%, 0.95%, 1.00%, 1.05%, 1.10%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35%, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70%, 1.75%, 1.80%, 1.85%, 1.41%, 1.53%, 1.54%, or 1.91%, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application can be obtained.

[0099] In this application, ZrO2 is an intermediate oxide in glass formation. An appropriate amount of ZrO2 can improve the chemical stability of microcrystalline glass, as well as its hardness, scratch resistance, and drop resistance. Furthermore, ZrO2 cations are often used as nucleating agents for microcrystalline glass because they have a high charge, a strong electric field, and a large concentration effect. However, if the ZrO2 content is too high, it can lead to phase separation of the glass, which is unfavorable for preparing microcrystalline glass with excellent optical properties. Therefore, in order to obtain microcrystalline glass with excellent optical properties and high mechanical strength, in this application, the molar percentage of ZrO2 in the base glass or microcrystalline glass is 4.20% to 4.85%, preferably 4.20% to 4.80%.

[0100] In some embodiments of this application, the ZrO2 content in the substrate glass or microcrystalline glass, expressed in mol% on an oxide basis, may be 4.20%, 4.35%, 4.40%, 4.45%, 4.50%, 4.55%, 4.60%, 4.65%, 4.70%, 4.75%, 4.74%, 4.84%, 4.33%, 4.34%, 4.85%, or 4.80%, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0101] In this application, Na2O is a network-modifying oxide. An appropriate amount of Na2O can supply free oxygen, improve the viscosity of the glass, facilitate its melting, promote its clarification, and adjust the rate of chemical strengthening. However, excessive Na2O leads to a decrease in the crystallinity of the microcrystalline glass and also affects the chemical strengthening effect of the microcrystalline glass. Therefore, in order to improve the formability of the base glass and the chemical strengthening effect of the microcrystalline glass, in this application, the molar percentage of Na2O in the base glass or microcrystalline glass is 1.80% to 3.20%, preferably 1.85% to 3.05%, and more preferably 2.20% to 3.00%.

[0102] In some embodiments of this application, the Na2O content in the substrate glass or microcrystalline glass, expressed in molar percentages based on oxides, is 1.80%, 1.85%, 1.90%, 1.95%, 2.00%, 2.05%, 2.10%, 2.15%, 2.20%, 2.25%, 2.30%, 2.35%, 2.40%, 2.45%, 2.50%, 2.55%, 2.60%, 2.65%, and 2.70%. The values ​​may be %, 2.75%, 2.80%, 2.85%, 2.90%, 2.95%, 3.00%, 3.20%, 2.36%, 2.96%, 3.01%, 2.93%, or 3.05%, or any value within a numerical range defined by any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0103] In this application, B2O3, as a flux, can reduce the high-temperature viscosity of glass, improve the problem of difficulty in melting due to ZrO2, and lower the yield point temperature of glass. However, excess B2O3 tends to worsen the transparency of microcrystalline glass. Therefore, in order to improve the moldability of the base glass and obtain microcrystalline glass with desired properties, in this application, the molar percentage of B2O3 in the base glass or microcrystalline glass is 0 to 1.00%, preferably 0 to 0.65%.

[0104] In some embodiments of this application, the B2O3 content in the substrate glass or microcrystalline glass, expressed in molar percentages based on oxides, may be 0, 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.65%, 0.70%, 0.80%, 0.90%, 1.00%, or 0.60%, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0105] In this application, Li2O is a component necessary for the formation of the lithium disilicate crystal phase, the main crystalline phase, and is an essential component for supplying lithium ions for ion exchange in the chemical strengthening process. An appropriate amount of Li2O contributes to improving the viscosity of the glass, making it easier to melt, promoting the clarification of the glass, and contributing to the acquisition of lithium disilicate crystals with the desired content. Furthermore, Li2O can supply alkali metal lithium ions for ion exchange with large radius ions (e.g., sodium ions) in the molten salt, and is one of the factors that affect the stress level of chemically strengthened microcrystalline glass. However, excess Li2O deteriorates the optical properties of microcrystalline glass. Therefore, in order to improve the formability of the base glass, obtain microcrystalline glass with the desired structure, and enhance the chemical strengthening effect of the microcrystalline glass, in this application, the molar percentage of Li2O in the base glass or microcrystalline glass is 25.32% to 26.52%, preferably 25.52% to 26.52%, and more preferably 25.52% to 26.00%.

[0106] In some embodiments of this application, the Li2O content in the substrate glass or microcrystalline glass, expressed in molar percentages based on oxides, is 25.32%, 25.52%, 25.60%, 25.65%, 25.70%, 25.75%, 25.80%, 25.85%, 25.90%, 25.95%, 26.00%, 26.05%, 26.10%, 26.15%, 26.20%, 26.25%, 26.30%, 26.35%. The values ​​may be %, 26.40%, 26.45%, 25.62%, 25.82%, 25.69%, 25.36%, 25.77%, 25.87%, 25.79%, 26.03%, 25.74%, or 26.52%, or any value within a numerical range defined by any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0107] In this application, by adjusting and controlling the range of content of each oxide component, particularly the mixing ratio between each oxide component, and especially the mol% relationship between Na2O, B2O3, ZrO2, and Li2O, it is possible to obtain microcrystalline glass that satisfies the desired crystalline phase structure and impart excellent optical properties and high intrinsic strength to the microcrystalline glass. Furthermore, it contributes to providing an excellent chemical strengthening effect to the resulting microcrystalline glass, and chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties can be rapidly and efficiently prepared from microcrystalline glass under normal chemical strengthening process conditions. Therefore, the manufacturing cost of high-strength chemically strengthened microcrystalline glass can be effectively reduced.

[0108] In some embodiments of this application, the value of Z, which represents the molar percentage relationship between Na2O, B2O3, and ZrO2 in the composition of the substrate glass or microcrystalline glass, may be 4.80, 4.85, 4.90, 4.95, 4.98, 5.05, 5.06, 5.07, 5.08, 5.09, 5.10, 5.11, 5.12, 5.13, 5.14, 5.15, 5.16, 5.17, 5.18, 5.19, 5.35, 5.30, or 5.20, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application can be obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application can be obtained.

[0109] In some embodiments of this application, the composition of the base glass or microcrystalline glass satisfies the relationship between the molar %[Na2O] of Na2O and the molar %[B2O3] of B2O3, which is 0.90% ≤ [Na2O] - [B2O3] ≤ 3.10%, preferably 1.25% ≤ [Na2O] - [B2O3] ≤ 3.02%, and more preferably 2.00% ≤ [Na2O] - [B2O3] ≤ 3.00%.

[0110] In some embodiments, the molar difference between Na2O and B2O3, [Na2O]-[B2O3], in the composition of the substrate glass or microcrystalline glass is 0.90%, 1.00%, 1.20%, 1.25%, 1.26%, 1.35%, 1.45%, 1.55%, 1.65%, 1.75%, 1.85%, 1.95%, 2.00%, 2.05%, 2.15%, 2.25%, 2.35%, 2.45%, 2.50%. The values ​​may be %, 2.55%, 2.65%, 2.75%, 2.85%, 2.95%, 3.10%, 1.79%, 0.96%, 2.36%, 2.96%, 3.01%, 2.93%, 3.00%, or 3.02%, or any value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0111] In some embodiments of this application, the composition of the base glass or microcrystalline glass satisfies the relationship between the molar %[Na2O] of Na2O and the molar %[Li2O] of Li2O, which is 8.55 ≤ [Li2O] / [Na2O] ≤ 13.85, preferably 8.55 ≤ [Li2O] / [Na2O] ≤ 11.50.

[0112] In some embodiments, the ratio of molar percentages of Li2O to Na2O, [Li2O] / [Na2O], in the composition of the base glass or microcrystalline glass may be 8.55, 9.00, 9.50, 10.00, 10.50, 10.55, 11.00, 11.50, 12.00, 12.50, 13.00, 13.50, 13.83, 10.93, 13.01, 10.92, 8.73, 8.61, 8.79, 8.83, or 13.85. Alternatively, it may be any value within a numerical range defined by any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0113] In some embodiments of this application, the composition of the base glass or microcrystalline glass may include other components in addition to the above composition range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. For example, in some embodiments, the composition of the base glass or microcrystalline glass, expressed in mol% on an oxide basis, may include CaO: 0.00 mol%-1.00 mol% and K2O: 0.00 mol%-1.00 mol%.

[0114] In this application, the phrases "the lithium disilicate crystalline phase has a higher weight percentage than other crystalline phases present in the microcrystalline glass," "the lithium disilicate is the main crystalline phase," or other similar expressions mean that the lithium disilicate crystalline phase accounts for 70% by weight (wt%) or more of all crystalline phases of the microcrystalline glass according to the embodiments of this application. In some embodiments, the weight percentage of the lithium disilicate crystalline phase in all crystalline phases of the microcrystalline glass is 70% or more, preferably 85% or more. For example, in all crystalline phases of microcrystalline glass, the weight percent of the lithium disilicate crystalline phase may be 70%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 96%, 97%, 98%, 100%, or 95%, or it may be a value within a numerical range formed with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0115] In some embodiments of this application, the crystallinity of the microcrystalline glass is 45% or higher, preferably 45% to 85%, and more preferably 55% to 65%. The higher the crystallinity of the microcrystalline glass, the more advantageous it is for the microcrystalline glass to obtain high impact resistance and high intrinsic strength. However, if the crystallinity is too high, it affects the chemical strengthening effect of the microcrystalline glass, increasing the chemical strengthening time required to obtain chemically strengthened microcrystalline glass with a high stress level, and also affecting the optical properties of the microcrystalline glass. In this application, by having a desired crystallinity of the microcrystalline glass, it is possible to impart excellent optical properties to the microcrystalline glass in addition to good impact resistance and high intrinsic strength, and to improve its chemical strengthening effect.

[0116] In some embodiments of this application, the degree of crystallinity of the microcrystalline glass may be 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85%, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required by this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required by this application is obtained.

[0117] In some embodiments of this application, non-limiting examples of other possible crystalline phases in the microcrystalline glass include a petalite crystalline phase and / or a lithium phosphate crystalline phase. In some embodiments, the microcrystalline glass further comprises a petalite crystalline phase, preferably with a weight percentage of 20% or less, more preferably 15% or less, 10% or less, or 5% or less of the petalite crystalline phase in the microcrystalline glass. In some embodiments, it is preferable that the microcrystalline glass does not contain a petalite crystalline phase. By suppressing the precipitation of other crystalline phases, it contributes to the formation of a desired interlock structure by the lithium disilicate, ensuring that the microcrystalline glass obtains high mechanical strength properties, excellent optical properties, and damage resistance.

[0118] In some embodiments of this application, the average grain size of the microcrystalline glass is 100 nm or less, preferably 40 nm or less, and more preferably 15 to 30 nm. An appropriate average grain size contributes to achieving both excellent optical properties and high intrinsic strength in the microcrystalline glass. If the average grain size is too high, the transparency of the microcrystalline glass is easily lost, and the chemical strengthening effect is also affected. In this application, by having an appropriate average grain size in the microcrystalline glass, in addition to good impact resistance and high intrinsic strength, excellent optical properties can be imparted to the microcrystalline glass, and its chemical strengthening effect can be improved.

[0119] In some embodiments, the average grain size of the microcrystalline glass may be 100 nm, 50 nm, 40 nm, 35 nm, 30 nm, 25 nm, 20 nm, 15 nm, or 10 nm, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0120] In some embodiments of this application, the microcrystalline glass is transparent in the visible light wavelength range, and preferably, when the thickness is 0.70 mm, the transmittance of the microcrystalline glass for 550 nm wavelength light is 90.00% or higher, preferably more than 90.40%. Microcrystalline glass that satisfies this transmittance has good light transmission and transparency and is suitable for use in displays where display effects are required. Here, "visible light wavelength range" refers to light with wavelengths from 360 nm to 740 nm.

[0121] In some embodiments, the transmittance of the microcrystalline glass for 550 nm wavelength light when the thickness is 0.70 mm may be 90.00%, 90.10%, 90.20%, 90.30%, 90.40%, 90.50%, 91.00%, 90.52%, 90.70%, 90.64%, 90.85%, 90.74%, 90.63%, 90.51%, or 92.00%, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints. In this application, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the required properties can be obtained, the transmittance of the microcrystalline glass may be, for example, 90% to 92% or 90.4% to 92%. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the required properties can be obtained.

[0122] In some embodiments of this application, the haze of the microcrystalline glass with a thickness of 0.70 mm is less than 0.30%. Haze refers to cloudiness or opacity caused by light scattering inside or on the surface of the microcrystalline glass. The smaller the haze, the better the transparency and display effect of the microcrystalline glass. In some embodiments, the haze of the microcrystalline glass with a thickness of 0.70 mm may be 0.25%, 0.20%, 0.15%, 0.10%, 0.05%, 0.21%, 0.14%, 0.12%, 0.14%, 0.16%, or 0.30%, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as the microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as the microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0123] In some embodiments of this application, the b-value of the microcrystalline glass with a thickness of 0.70 mm is less than 0.70, preferably 0.60 or less. In this application, the b-value is the optical b-value measured under a D65 light source. In this application, the b-value is measured in transmission mode using a Konica Minolta CM-3600A, and the result is shown as b(D65). The smaller the b-value, the better the display effect of the microcrystalline glass. If the b-value is large, undesirable colors appear in the microcrystalline glass, and the display effect of the glass can no longer meet the requirements of the display cover glass.

[0124] In some embodiments, the b-value of the microcrystalline glass with a thickness of 0.70 mm may be 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.48, 0.47, 0.52, 0.51, 0.54, or 0.20, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application can be obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application can be obtained.

[0125] The microcrystalline glass according to this application exhibits high transmittance, low haze, and a low b-value. This indicates that the microcrystalline glass according to this application has excellent optical properties and uniformity, is transparent, and can meet the requirements for cover glass in electronic device displays.

[0126] In some embodiments of this application, the Young's modulus of the microcrystalline glass is 100 GPa or more, preferably 105 to 112.50 GPa. By setting the Young's modulus of the microcrystalline glass to 100 GPa or more, this application ensures a high-strength network structure of the microcrystalline glass, reduces the stress relaxation effect generated during ion exchange in the microcrystalline glass, and mitigates the suppressive effect on deep stress in composite compressive stress caused by factors such as high temperature and long duration during ion exchange.

[0127] In some embodiments, the Young's modulus of the microcrystalline glass may be 100 GPa, 105 GPa, 110 GPa, 106.32 GPa, 111.12 GPa, 110.82 GPa, 111.32 GPa, 110.91 GPa, 112.10 GPa, 111.87 GPa, or 112.50 GPa, or, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the required properties in the present application is obtained, it may also be a value within a numerical range formed by any two of the above specific values as endpoints. Further, in a specific embodiment, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the required properties in the present application is obtained, any of the above ranges can be combined with any other range.

[0128] In some embodiments of the present application, the Vickers hardness of the microcrystalline glass is 640 kgf / mm 2 or more, preferably 640 - 680 kgf / mm 2 is. The fact that the Vickers hardness of this microcrystalline glass is within the above range indicates that the microcrystalline glass has high hardness and high intrinsic strength, ensuring its excellent mechanical properties, and making it possible to prepare a chemically strengthened microcrystalline glass having high mechanical strength properties and excellent damage resistance from the microcrystalline glass.

[0129] In some embodiments, the Vickers hardness of the microcrystalline glass is 640 kgf / mm 2 、650 kgf / mm 2 、660 kgf / mm 2 、670 kgf / mm 2 、660.12 kgf / mm 2 、654.02 kgf / mm 2 、650.20 kgf / mm 2 、652.31 kgf / mm 2 、659.65 kgf / mm 2 、651.70 kgf / mm 2 、654.92, or 680 kgf / mm 2It may be any of the above, or it may be any value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application can be obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the properties required in this application can be obtained.

[0130] In some embodiments, the microcrystalline glass includes planar microcrystalline glass or curved microcrystalline glass. Preferably, when the microcrystalline glass is curved microcrystalline glass, it can be prepared by subjecting a crystallized glass material with a crystallinity of 5% or more to a three-dimensional hot bending process. Although not bound by any theory, this application describes using a partially crystallized crystallized glass material and performing three-dimensional hot bending so that the glass deforms while simultaneously continuing to crystallize with heat until the target crystallinity is reached. This allows for more precise control of the amount of deformation after three-dimensional hot bending, reduces variations in the tolerance of the contour, makes the dimensions more stable, and improves the dimensional accuracy of the curved microcrystalline glass after hot bending. Those skilled in the art can select the crystallinity of the partially crystallized glass material according to the desired crystallinity of the curved microcrystalline glass. For example, if the desired degree of crystallinity of the curved microcrystalline glass is approximately 60%, a partially crystallized glass material with a degree of crystallinity of 50% can be selected and subjected to hot bending to obtain a curved microcrystalline glass that satisfies the target degree of crystallinity. In this application, the composition of the partially crystallized glass, expressed in mol% based on oxides, is the same as or substantially the same as the composition of the microcrystalline glass.

[0131] In some embodiments, the thickness of the microcrystalline glass is 0.10 to 5.00 mm. Exemplarily, the thickness of the microcrystalline glass may be 0.10 to 2.00 mm, 0.20 to 1.00 mm, or 0.40 to 0.80 mm.

[0132] The composition and microstructure of microcrystalline glass have been described above; the preparation method for microcrystalline glass will now be explained in detail.

[0133] In this application, the preparation process for microcrystalline glass mainly includes the preparation process for a base glass and the heat treatment process for the base glass.

[0134] In this application, the base glass may be prepared by, but is not limited to, conventional molding methods. For example, the molding method for the base glass includes, but is not limited to, the float method, the overflow method, the rolling method, and the casting method. Exemplarily, the base glass can be obtained by uniformly mixing each component according to a recipe, melt-molding, cooling, and annealing.

[0135] Exemplary, each raw material (industrially used raw materials) is blended according to the proportions shown in the recipe, a clarifying agent is added, and the mixture is mixed for a certain period of time to obtain a uniformly mixed raw material mixture. The raw material mixture is placed in a platinum crucible and heated to a melting temperature of 1250°C to 1680°C, preferably 1480°C to 1680°C, and held at this temperature for 3 to 12 hours. Then, it is placed in a mold and cooled and molded, preferably cooled to 750°C to 1000°C, and then annealed in an annealing furnace. The annealing temperature is preferably 400°C to 650°C and the annealing time is preferably 10 to 48 hours. After that, the mixture is cooled to room temperature while still in the furnace to obtain a base glass. Those skilled in the art can select the type and amount of clarifying agent according to their needs without employing inventive capabilities. Furthermore, the clarifying agent includes, but is not limited to, one or more of the following: sodium chloride, tin oxide, antimony oxide, arsenic oxide, etc. The amount of clarifying agent added can be 0 to 1 wt% of the total amount of each raw material.

[0136] In some embodiments of this application, the heat treatment step of the base glass may include a nucleation treatment and / or a crystallization treatment, but preferably, a nucleation treatment and a crystallization treatment are used. In some embodiments, the crystallization treatment includes a one-stage crystallization treatment or a two-stage crystallization treatment. In some embodiments, when a two-stage crystallization treatment is employed for the preparation of curved microcrystalline glass, the second crystallization treatment step involves heating the crystallized glass material obtained in the first crystallization treatment step to a crystallization temperature and performing a three-dimensional hot bending and forming treatment, thereby performing secondary crystallization during the three-dimensional hot bending and forming process.

[0137] In some embodiments of this application, the heat treatment of the substrate glass may be performed in one step or in two or more steps in order to obtain desired physical and chemical properties from the microcrystalline glass. In the case of one-step heat treatment, a one-step heating treatment is performed directly without a separate nucleation treatment, and nucleation and crystal growth are carried out at the temperature reached in this one-step heating treatment. In other words, direct crystallization treatment is performed. In the case of two-step heat treatment, the two-step heating treatment may include, but is not limited to, an embodiment in which a nucleation treatment is performed first, and then a crystal growth treatment, i.e., crystallization treatment, is performed to obtain the target crystal.

[0138] To precipitate a desired crystalline phase in microcrystalline glass and obtain the desired physical and chemical properties, the nucleation treatment temperature can be set to 530-600°C, the nucleation treatment time to 0-24 hours, preferably 2-8 hours, and the crystallization treatment temperature to 700-750°C, the crystallization treatment time to 0.10-24 hours, preferably 1-3 hours. During the heat treatment, the heating rate is preferably 5-15°C / min, and more preferably 10°C / min. Here, the nucleation treatment temperature is the temperature at which crystal nuclei can be formed. The crystallization treatment temperature is the temperature appropriate for the growth of the target crystal.

[0139] After heat treatment, those skilled in the art may perform other conventional steps, such as molding, cutting (e.g., cutting with a multi-wire saw), CNC machining (computer numerical control), slimming, and polishing, to obtain a microcrystalline glass sample that meets the desired specifications and requirements.

[0140] In some embodiments of this application, chemically strengthened microcrystalline glass is further provided, which is prepared from the above-mentioned microcrystalline glass by a chemical strengthening treatment. The chemically strengthened microcrystalline glass has the same composition in its core as the microcrystalline glass described in any of the above embodiments, includes a compressive stress layer region extending from the surface to the compression depth, and has tensile stress internally. That is, the chemically strengthened microcrystalline glass includes a compressive stress layer and a tensile stress layer.

[0141] Chemical strengthening, also known as ion exchange, involves impregnating microcrystalline glass with a molten salt and exchanging alkali metal ions with smaller ionic radii in the microcrystalline glass with alkali metal ions with larger ionic radii in the molten salt. This process forms a compressive stress layer on the surface of the microcrystalline glass, resulting in chemically strengthened microcrystalline glass with superior mechanical properties.

[0142] Furthermore, the surface composition of microcrystalline glass after chemical strengthening may differ from that of newly formed microcrystalline glass (i.e., microcrystalline glass before chemical strengthening and without ion exchange) compared to microcrystalline glass before chemical strengthening. This is because, during ion exchange, alkali metal ions (e.g., Li+ or Na+) on the surface of newly formed microcrystalline glass are replaced by larger alkali metal ions (e.g., Na+ or K+). However, in this embodiment, the composition and crystalline phase aggregate in or near the center of the depth of the microcrystalline glass still have the composition and crystalline phase aggregate of newly formed microcrystalline glass. In other words, in this application, the composition (e.g., the composition of the tensile stress layer) and crystalline phase aggregate of the center of the chemically strengthened microcrystalline glass obtained by chemical strengthening is identical or substantially identical to that of newly formed microcrystalline glass.

[0143] In some embodiments of this application, the chemical strengthening treatment can be a one-step or multi-step method. The molten salt for the chemical strengthening treatment is a molten salt containing a sodium salt and / or a potassium salt. Preferably, the molten salt for the chemical strengthening treatment according to this application is a mixed molten salt containing a sodium salt and a potassium salt. The temperature of the molten salt is preferably 380°C to 470°C, more preferably 430°C to 460°C. In some embodiments of this application, it is preferable that the concentration of potassium salt in the molten salt is 0 wt% to 90 wt%, and the concentration of sodium salt is 10 wt% to 100 wt%, and it is more preferable to add a certain amount (e.g., 0 to 0.2 wt%) of lithium salt to the molten salt. In some embodiments of this application, the duration of the chemical strengthening treatment is preferably 0.1 to 3 hours. The sodium salt is at least one selected from sodium nitrate, sodium sulfate, and sodium carbonate, preferably sodium nitrate. The potassium salt is at least one selected from potassium nitrate, potassium sulfate, and potassium carbonate, preferably potassium nitrate. The lithium salt is at least one selected from lithium nitrate, lithium sulfate, and lithium carbonate, and is preferably lithium nitrate.

[0144] In some embodiments of this application, the chemically strengthened microcrystalline glass comprises a lithium disilicate crystalline phase having a higher weight percentage than other crystalline phases present in the chemically strengthened microcrystalline glass, wherein the central components of the chemically strengthened microcrystalline glass are, in molar percentages based on oxide, SiO2: 61.50%~63.40%, Al2O3: 2.75%~2.99%, and P2O5: 0.91%~1.9%. The composition of the chemically strengthened microcrystalline glass in the center of the glass is such that the molar percentages of Na2O[Na2O], B2O3[B2O3], and ZrO2[ZrO2] are equal to Z = -1.344 × (2.65 - 100 × [Na2O]). 2 The formula is +0.466 × 100 × [B2O3] + 1.203 × 100 × [ZrO2], satisfying the relationship 4.80 ≤ Z ≤ 5.35, preferably 4.98 ≤ Z ≤ 5.20.

[0145] In some embodiments of this application, in the composition of the central part of the chemically strengthened microcrystalline glass, the molar %[Na2O] of Na2O and the molar %[B2O3] of B2O3 satisfy the relationship 0.90%≦[Na2O]-[B2O3]≦3.10%, preferably 1.25%≦[Na2O]-[B2O3]≦3.02%, more preferably 2.00%≦[Na2O]-[B2O3]≦3.00%, and / or, in the composition of the central part of the chemically strengthened microcrystalline glass, the molar %[Na2O] of Na2O and the molar %[Li2O] of Li2O satisfy the relationship 8.55≦[Li2O] / [Na2O]≦13.85, preferably 8.55≦[Li2O] / [Na2O]≦11.50.

[0146] In some embodiments of this application, the chemically strengthened microcrystalline glass has a CT_LD of 45,000 to 55,000 MPa / mm, preferably 48,000 to 53,000 MPa / mm, where CT_LD is the tensile stress linear density. By limiting the CT_LD of the chemically strengthened microcrystalline glass to 45,000 to 55,000 MPa / mm, the tensile stress accumulated inside the chemically strengthened microcrystalline glass becomes sufficiently dense, ensuring a high surface stress level and excellent damage resistance, such as drop resistance, to meet market demands.

[0147] In some embodiments, the CT_LD of the chemically strengthened microcrystalline glass may be 45000MPa / mm, 46000MPa / mm, 47000MPa / mm, 48000MPa / mm, 49000MPa / mm, 50000MPa / mm, 51000MPa / mm, 52000MPa / mm, 53000MPa / mm, 54000MPa / mm, 50479MPa / mm, 50547MPa / mm, 50297MPa / mm, 50497MPa / mm, 50833MPa / mm, 52768MPa / mm, or 55000MPa / mm, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the properties required in this application can be obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a chemically strengthened microcrystalline glass having the properties required in this application can be obtained.

[0148] In some embodiments of this application, the chemically strengthened microcrystalline glass has a CS_50 of 150 to 199 MPa, preferably 160 to 199 MPa. CS_50 is the compressive stress value at a depth of 50 μm from the main surface of the chemically strengthened microcrystalline glass. When a blunt or sharp object comes into contact with the chemically strengthened microcrystalline glass, the stress structure on the surface of the chemically strengthened microcrystalline glass will preferentially counteract the impact force received. By having a high surface stress level, the chemically strengthened microcrystalline glass can counteract more residual energy from drops, presses, impacts, and collisions, ensuring its excellent resistance to damage, such as drop resistance.

[0149] In some embodiments, the CS_50 of the chemically strengthened microcrystalline glass may be 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, 163.97 MPa, 173.80 MPa, 168.90 MPa, 174.60 MPa, 178.20 MPa, 176.89 MPa, 179.72 MPa, or 199 MPa, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0150] In some embodiments of this application, the chemically strengthened microcrystalline glass has a |CT_AV| of 80 to 98 MPa, where |CT_AV| is the absolute value of the average tensile stress in the tensile stress layer. Setting the |CT_AV| of the chemically strengthened microcrystalline glass to 80 to 98 MPa contributes to the chemically strengthened microcrystalline glass having a good tensile stress distribution structure, i.e., a high surface stress level. A high surface compressive stress level allows for the offsetting of more residual energy from drops, presses, impacts, and collisions, resulting in the chemically strengthened microcrystalline glass having excellent damage resistance.

[0151] In some embodiments, |CT_AV| of the chemically strengthened microcrystalline glass may be 80 MPa, 85 MPa, 90 MPa, 95 MPa, 96.94 MPa, 86.77 MPa, 89.37 MPa, 90.20 MPa, 92.10 MPa, 91.58 MPa, 93.60 MPa, or 98 MPa, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0152] In some embodiments of this application, the chemically strengthened microcrystalline glass has a |CT_CV| of 115 to 142 MPa, where |CT_CV| is the absolute value of the maximum tensile stress. Preferably, the chemically strengthened microcrystalline glass has a |CT_CV| of 120 to 140 MPa. By setting the |CT_CV| of the chemically strengthened microcrystalline glass to 115 to 142 MPa, a high surface stress level of the chemically strengthened microcrystalline glass is ensured. A high surface compressive stress level allows for the offsetting of residual energy from more drops, presses, impacts, and collisions, resulting in the chemically strengthened microcrystalline glass having excellent damage resistance.

[0153] In some embodiments, |CT_CV| of the chemically strengthened microcrystalline glass may be 115 MPa, 120 MPa, 125 MPa, 130 MPa, 135 MPa, 125.68 MPa, 133.49 MPa, 136.28 MPa, 141.54 MPa, 141.63 MPa, 138.76 MPa, or 142 MPa, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained.

[0154] In some embodiments of this application, the Vickers hardness of the chemically strengthened microcrystalline glass is 680 kgf / mm². 2 Preferably, 700 kgf / mm² 2 ~800 kgf / mm 2 By setting the Vickers hardness of the chemically strengthened microcrystalline glass within the above range, high hardness and high mechanical strength properties can be imparted to the chemically strengthened microcrystalline glass, resulting in excellent damage resistance.

[0155] In some embodiments, the Vickers hardness of the chemically strengthened microcrystalline glass is 680 kgf / mm². 2 690 kgf / mm 2 700 kgf / mm 2 710 kgf / mm 2 720 kgf / mm 2 730 kgf / mm 2 740 kgf / mm 2 750 kgf / mm 2 760 kgf / mm 2 770 kgf / mm 2 780 kgf / mm 2 790 kgf / mm 2 726.25 kgf / mm 2 723.96 kgf / mm 2 724.50 kgf / mm 2 720.31 kgf / mm 2 730.98 kgf / mm 2 718.60 kgf / mm 2 731.57 kgf / mm 2 , or 800 kgf / mm 2 It may be any of the above, or, as long as a chemically strengthened microcrystalline glass having the properties required in this application can be obtained, it may be any value within a numerical range configured with any two of the above specific values ​​as endpoints. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range as long as a chemically strengthened microcrystalline glass having the properties required in this application can be obtained.

[0156] In some embodiments of this application, the chemically strengthened microcrystalline glass has a DOL_0 of 0.18t to 0.25t, preferably 0.20t to 0.25t, where DOL_0 is the depth of the compressive stress layer and t is the thickness of the chemically strengthened microcrystalline glass. By providing the chemically strengthened microcrystalline glass with an appropriate DOL_0, it is possible to prevent cracks that are suddenly generated by impact or puncture from a blunt or sharp object from directly penetrating the compressive stress region and reaching the tensile stress region, thereby preventing the microcrystalline glass from cracking. Thus, the chemically strengthened microcrystalline glass has improved properties that counteract the energy that propagates cracks, ensuring damage resistance such as excellent drop resistance.

[0157] In some embodiments, the DOL_0 of the chemically strengthened microcrystalline glass may be 0.18t, 0.20t, 0.21t, 0.22t, 0.23t, 0.24t, or 0.25t, or it may be a value within a numerical range configured with any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained. Furthermore, in specific embodiments, any of the above ranges can be combined with any other range, as long as a chemically strengthened microcrystalline glass having the properties required in this application is obtained. For example, when the thickness of the chemically strengthened microcrystalline glass is 0.7 mm, the DOL_0 of the chemically strengthened microcrystalline glass may be 152.94 μm, 142.25 μm, 143.26 μm, 144.20 μm, 143.80 μm, 142.67 μm, 144.26 μm, 126 μm, 130 μm, 135 μm, 140 μm, 150 μm, or 160 μm, or it may be a value within a numerical range formed with any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the properties required in this application can be obtained.

[0158] In some embodiments of this application, the microcrystalline glass or chemically strengthened microcrystalline glass may have a two-dimensional (2D), 2.5-dimensional (2.5D), three-dimensional (3D), or amorphous shape, and / or the microcrystalline glass or chemically strengthened microcrystalline glass may be of uniform thickness or unequal thickness. Those skilled in the art can select according to their needs. Herein, "unequal thickness" means that the microcrystalline glass or chemically strengthened microcrystalline glass contains at least two portions of different thicknesses.

[0159] In this application, by making the chemically strengthened microcrystalline glass satisfy specific stress characteristics, the chemically strengthened microcrystalline glass will have excellent mechanical strength characteristics, excellent mechanical strength characteristics, excellent damage resistance, and especially excellent drop resistance.

[0160] In some embodiments of this application, a sandpaper drop test is performed on the chemically strengthened microcrystalline glass having a thickness of 0.7 mm using 80-mesh sandpaper. The average drop height of the chemically strengthened microcrystalline glass is 1.0 m or more, preferably 1.2 m or more, and more preferably 1.5 m or more. This ensures that the chemically strengthened microcrystalline glass according to this application has excellent drop resistance. In some embodiments, a sandpaper drop test is performed on the chemically strengthened microcrystalline glass having a thickness of 0.7 mm using 80-mesh sandpaper, and the average drop height of the chemically strengthened microcrystalline glass may be 1.0 m, 1.1 m, 1.2 m, 1.3 m, 1.4 m, 1.5 m, 1.6 m, 1.7 m, 1.8 m, 1.9 m, 2.0 m, 1.75 m, 1.68 m, 1.64 m, 1.57 m, 1.60 m, 1.62 m, 1.78 m, or 2.1 m, etc.

[0161] The microcrystalline glass or chemically strengthened microcrystalline glass possessing superior properties as described in this application is applicable to electronic devices, including, but not limited to, mobile phones, tablet computers, portable game consoles, portable digital devices (e.g., digital cameras), in-vehicle central control units, electronic whiteboard glass, smart homes, and smart wear (e.g., smart bracelets, smartwatches, smart glasses). Furthermore, the microcrystalline glass or chemically strengthened microcrystalline glass is applicable to vehicles, aircraft, and any glass components requiring microcrystalline glass. For example, it is applicable to displays, cover glass, touchscreens, glass inner screens, or inner frames of electronic devices, and to window glass such as windshields or side windows of vehicles, aircraft, and other vehicles. It is also applicable to worktops, other surfaces, electric doors, floor tiles, wall panels, and storage containers. Other surfaces include, but are not limited to, exterior wall surfaces, stair treads, column surfaces, and counter surfaces. Storage containers include, but are not limited to, cups, plates, pill bottles, and beverage bottles.

[0162] Exemplary examples, the excellent properties of microcrystalline glass or chemically strengthened microcrystalline glass described herein can be used in the manufacture of glass components. The glass components referred to herein may be regular or irregular and can be manufactured according to the needs of those skilled in the art.

[0163] Exemplary, the excellent properties of microcrystalline glass or chemically strengthened microcrystalline glass according to this application can be used in the manufacture of cover glass. The cover glass may be a display cover, a back cover, or a camera protective cover for an electronic device. Exemplary, the excellent properties of microcrystalline glass or chemically strengthened microcrystalline glass according to this application can be used in an electronic device. As shown in Figures 9, 10, and 11, embodiments of this application provide an electronic device. This electronic device may be an electronic product such as a mobile phone, a tablet computer, or a smart wearable device. The electronic device includes a housing 1 mounted on the outside of the electronic device and elements such as a circuit board and a battery built inside the housing 1. The housing 1 includes a display cover 11 mounted on the front and a back cover 12 mounted on the back. The display cover 11 is provided on a display module 4. The display cover 11 and / or the back cover 12 can be made of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass. In the embodiments of this application, the display cover 11 and the back cover 12 may be made of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass as a whole, or only partially. In the embodiments of this application, the display may be a touch display, and the display cover 11 may be a protective cover provided on the touch display. In the embodiments of this application, the back cover 12 may cover only the back of the electronic device (i.e., the side away from the display), or it may cover both the back and the side frame of the electronic device. Optionally, the back cover 12 may cover all of the side frame around the electronic device, or it may cover only some of the side frame.

[0164] In some embodiments of this application, as shown in Figure 10, the electronic device further includes a camera element 2 housed inside a housing 1, and the housing 1 may include a camera protection cover 13 provided on the camera element 2 for protecting the camera element 2. The camera protection cover 13 can be made of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass. In embodiments of this application, the camera protection cover 13 may be made entirely of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass, or only partially of it. In embodiments of this application, the camera protection cover 13 may be provided at a position corresponding to the position of the camera element 2, and may be provided on the front of the electronic device or on the back of the electronic device. In some embodiments of this application, the camera protection cover 13 may be configured separately from the display cover 11 or the back cover 12. In another embodiment of this application, the camera protection cover 13 may be configured integrally with the display cover 11 or the back cover 12.

[0165] In some embodiments of this application, as shown in Figure 11, the electronic device further includes an intermediate frame 3 positioned between the display module 4 and the housing 1, the intermediate frame 3 may include the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass.

[0166] In the embodiments of this application, any one of the display cover, back cover, camera protective cover, and intermediate frame of the electronic device may be made of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass, any two of them may be made of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass, any three of them may be made of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass, or all four may be made of the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass.

[0167] In some embodiments of this application, the display cover, back cover, camera protection cover, and intermediate frame of the electronic device may have a two-dimensional, 2.5-dimensional, three-dimensional, or irregular shape. In some embodiments of this application, the display cover, back cover, camera protection cover, and intermediate frame of the electronic device may have uniform or unequal thickness.

[0168] Those skilled in the art can select the thickness of the microcrystalline glass or chemically strengthened microcrystalline glass according to their needs. For example, the thickness of the microcrystalline glass or chemically strengthened microcrystalline glass may be 0.1 to 5 mm, 0.1 to 2.0 mm, 0.2 to 1 mm, or 0.4 to 0.8 mm.

[0169] The technical invention of this application will be further described below with reference to examples. The examples of this application described in detail below are merely illustrative for the purpose of illustrating this application and are not intended to limit this application.

[0170] Example 1 (1) Preparation of the base glass Each raw material (a raw material commonly used in industry) was blended according to the recipe shown in Table 1, and the total mass of the blended raw materials was set to 1000g. Then, 5g of sodium chloride (NaCl) as a clarifying agent was added to the blended raw materials, and the mixture was mixed in a V-type mixer for 30 minutes to obtain a uniformly mixed raw material mixture.

[0171] The raw material mixture was transferred to a platinum crucible, melted at 1650°C for 5 hours, then cooled and molded in a mold, and cooled to 900°C. After that, it was annealed in a 500°C annealing furnace for 24 hours, and then cooled to room temperature while still in the furnace to obtain a base glass block.

[0172] (2) Preparation of microcrystalline glass The substrate glass block was placed in an annealing furnace and heated from room temperature to 550°C at a heating rate of 10°C / min to perform nucleation treatment. After holding at this temperature for 4 hours, the temperature was heated again to 710°C at a heating rate of 10°C / min to perform crystallization treatment. After holding at this temperature for 1.5 hours, the temperature was cooled to room temperature at a cooling rate of 1°C / min to obtain a microcrystalline glass block sample. The prepared microcrystalline glass had the same composition as the substrate glass in molar percentage based on oxide, as detailed in Table 1.

[0173] By sequentially performing cold working processes—cutting, CNC machining (the model number of the CNC machine used in this application is RCG500S)—on the obtained microcrystalline glass block sample, a microcrystalline glass sample that met the desired specifications and requirements was prepared. In this application, the above cold working processes were performed on a microcrystalline glass block sample to prepare a microcrystalline glass sample with a thickness of 0.70 mm. Specifically, a polished sheet of microcrystalline glass sample measuring 50 mm × 50 mm × 0.70 mm was prepared.

[0174] The following tests were performed on the microcrystalline glass sample obtained in Example 1.

[0175] For microcrystalline glass samples, the crystalline phase composition, degree of crystallinity, average grain size, Vickers hardness, and Young's modulus were measured. Additionally, the optical b-value, haze, and transmittance (at a wavelength of 550 nm) of a 0.7 mm thick microcrystalline glass sample were measured, and the results are shown in Table 2.

[0176] (3) Preparation of chemically strengthened microcrystalline glass The obtained microcrystalline glass samples were placed in a strengthening furnace and preheated for 5 minutes, then immediately placed in a molten salt solution at 460°C for chemical strengthening. The composition of the molten salt solution was 70 wt% KNO3 + 30 wt% NaNO3 + 0.03 wt% LiNO3 (0.03 wt% LiNO3 was added based on the total mass of KNO3 and NaNO3). After 2 hours of chemical strengthening, the microcrystalline glass samples were removed and slowly cooled to room temperature in the strengthening furnace. Subsequently, the salt residue on the surface of the microcrystalline glass was washed off with water, and the microcrystalline glass samples were dried to obtain chemically strengthened microcrystalline glass.

[0177] The following tests were performed on the chemically strengthened microcrystalline glass obtained in Example 1.

[0178] I. For chemically strengthened microcrystalline glass, |CT_CV|, DOL_0, CS_50, and |CT_AV| were measured using an SLP-2000 stress meter (light source wavelength: 518 nm, SOC = 26 (nm / cm) / MPa, refractive index: 1.56, exposure time: 300 μsec). Furthermore, the tensile stress linear density (CT_LD) was calculated, and the results are shown in Table 3.

[0179] II. The Vickers hardness of chemically strengthened microcrystalline glass was measured, and the results are shown in Table 3.

[0180] III. The average drop height of chemically strengthened microcrystalline glass was measured, and the results are shown in Table 3.

[0181] Examples 2 to 7 Each example was carried out with reference to Example 1, and the raw material composition, different process parameters, and corresponding test results for each example are shown in Tables 1 to 3.

[0182] Figure 1 shows the XRD pattern of the microcrystalline glass according to Example 2. As can be seen from Figure 1, the main crystalline phase in the microcrystalline glass is the lithium disilicate crystalline phase.

[0183] Figure 2 shows the transmittance curve of the microcrystalline glass according to Example 2. As can be seen from Figure 2, the microcrystalline glass is transparent in the visible light wavelength range and has high transmittance.

[0184] Figure 3 shows a comparison of the XRD patterns of the microcrystalline glass before and after chemical strengthening according to Example 2. As can be seen from Figure 3, the crystalline phase structure of the microcrystalline glass does not change significantly before and after the chemical strengthening treatment, and the main crystalline phase of the chemically strengthened microcrystals prepared from the microcrystalline glass is also the lithium disilicate crystalline phase.

[0185] Figures 4 and 5 show actual images of the microcrystalline glass according to Example 2 and Example 7, respectively. To show the state of the microcrystalline glass sheet, the images were taken on paper with a black background. As can be seen from Figures 4 and 5, the microcrystalline glass according to this application has a small b value, so it is almost colorless and transparent, and can achieve a good display effect.

[0186] Comparative Examples 1 to 12 Each comparative example was carried out with reference to Example 1, and the raw material composition, different process parameters, and corresponding test results for each comparative example are shown in Tables 1 to 3.

[0187] Figures 6, 7, and 8 show actual images of the microcrystalline glass according to Comparative Example 5, Comparative Example 6, and Comparative Example 8, respectively. To show the state of the microcrystalline glass sheet, the images were taken on paper with a black background. As can be seen from Figures 6, 7, and 8, the microcrystalline glass according to the comparative examples clearly exhibits a bluish tint due to its high b-value. The higher the b-value, the more pronounced the blue tint becomes, and the greater the impact on the display effect.

[0188] [Table 1]

[0189] Here, if the oxide content in Table 1 is "0", it indicates that the component may exist as an impurity rather than being actively or intentionally added to the glass composition during the initial raw material blending process. This table expresses the content in mole percent based on oxides and substitutes these values ​​into each formula, so the mole unit is not involved in the calculation of the formulas.

[0190] [Table 2]

[0191] [Table 3]

[0192] As can be seen from the examples and comparative examples in Tables 1 to 3 above, compared to the comparative examples, the examples of this application satisfy the requirements within a specific range by controlling the molar percentage relationships between Na2O, B2O3, ZrO2, and Li2O while satisfying the range of content of each oxide by controlling the compositional components and mixing ratios of the microcrystalline glass. Furthermore, by forming a microstructure in which lithium disilicate is the main crystalline phase in the microcrystalline glass, excellent optical properties (e.g., high transmittance, low haze, low b value) and high intrinsic strength (e.g., high Young's modulus and high Vickers hardness) are imparted to the microcrystalline glass. Moreover, it is possible to rapidly and efficiently prepare chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties under normal chemical strengthening process conditions using microcrystalline glass. The chemically strengthened microcrystalline glass according to the examples of this application has high CS_50, |CT_AV|, DOL_0, and CT_LD, and excellent drop resistance.

[0193] On the other hand, in Comparative Examples 1 to 12, the composition of the glass does not simultaneously satisfy the range of content of each oxide specified in this application and the molar percentage relationship between Na2O, B2O3, ZrO2, and Li2O. As a result, in each comparative example, the optical properties of the prepared microcrystalline glass are poor, such as low transmittance, high optical b value, and high haze. Furthermore, under similar chemical strengthening process conditions, the stress properties of the prepared chemically strengthened microcrystalline glass may be inferior to those of the examples, resulting in poor drop resistance. In other words, the comparative examples do not simultaneously satisfy the requirements of this application and therefore cannot achieve both excellent optical properties and a high stress level.

[0194] The embodiments described above are merely specific examples of the present application and do not limit it. Those skilled in the art may have various modifications and changes to the present application. Any modifications, equivalent substitutions, or improvements made, provided they do not deviate from the spirit and principles of the present application, are within the scope of protection of this application.

[0195] Industrial applicability According to this application, by giving microcrystalline glass a specific composition and crystal phase structure, setting the content and blending ratio of each component within a specific range, setting the molar percentages of Na2O, B2O3, ZrO2, and Li2O, and making lithium disilicate the main crystal phase of the microcrystalline glass, it is possible to impart excellent optical properties and high intrinsic strength to the microcrystalline glass. Furthermore, it is possible to rapidly and efficiently prepare chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties under normal chemical strengthening process conditions using microcrystalline glass. Therefore, the manufacturing cost of high-strength chemically strengthened microcrystalline glass can be effectively reduced. [Explanation of Symbols]

[0196] 11 Display Cover 12 Back lid 13 Camera protective cover 2 Camera elements 3 Intermediate slot 4 Display Module

Claims

1. It is a microcrystalline glass, The microcrystalline glass contains a lithium disilicate crystalline phase having a higher weight percentage than other crystalline phases present in the aforementioned microcrystalline glass. As components of the microcrystalline glass, in terms of mol% based on oxides, SiO ２ : 61.50% to 63.40%, Al ２ O ３ : 2.75% to 2.99%, P ２ O ５ : 0.91% to 1.91%, ZrO ２ : 4.20% to 4.85%, Na ２ O: 1.80% to 3.20%, B ２ O ３ : 0 to 1.00%, Li ２ O: including 25.32% to 26.52%, In the composition of the aforementioned microcrystalline glass, Na ２ Mole percent of O [Na ２ O] and B ２ O ３ mol% [B ２ O ３ ] and ZrO ２ mol% of [ZrO ２ ] means, Z=-1.344×(2.65-100×[Na ２ O]) ２ +0.466×100×[B ２ O ３ ]+1.203×100×[ZrO ２ ] satisfies the relationship 4.98 ≤ Z ≤ 5.35 The thickness is 0.70 mm, and the b-value of the microcrystalline glass is less than 0.

70. A microcrystalline glass characterized by the following features.

2. The microcrystalline glass according to claim 1, characterized in that it satisfies the relationship 4.98 ≤ Z ≤ 5.

20.

3. In the composition of the aforementioned microcrystalline glass, Na ２ Mole percent of O [Na ２ O] and B ２ O ３ mol% [B ２ O ３ ] means, 0.90% ≤ [Na ２ O] - [B] ２ O ３ The relationship ≤ 3.10% is satisfied. The microcrystalline glass according to feature 1.

4. In the composition of the aforementioned microcrystalline glass, Na ２ Mole percent of O [Na ２ O] and B ２ O ３ mol% [B ２ O ３ ] means, 1.25% ≤ [Na ２ O] - [B] ２ O ３ The relationship ≤ 3.02% is satisfied. The microcrystalline glass according to feature 3.

5. In the composition of the aforementioned microcrystalline glass, Na ２ Mole percent of O [Na ２ O] and B ２ O ３ mol% [B ２ O ３ ] means, 2.00% ≤ [Na ２ O] - [B] ２ O ３ The relationship ≤ 3.00% is satisfied. The microcrystalline glass according to feature 3.

6. In the composition of the aforementioned microcrystalline glass, Na ２ Mole percent of O [Na ２ O] and Li ２ Mole percent of O [Li ２ O] means, 8.55 ≤ [Li ２ O] / [Na ２ The relationship O ≤ 13.85 is satisfied. The microcrystalline glass according to feature 1.

7. In the composition of the aforementioned microcrystalline glass, Na ２ Mole percent of O [Na ２ O] and Li ２ Mole percent of O [Li ２ O] means, 8.55 ≤ [Li ２ O] / [Na ２ The relationship O ≤ 11.50 is satisfied. The microcrystalline glass according to feature 6.

8. In all crystalline phases of the aforementioned microcrystalline glass, the weight % of the lithium disilicate crystalline phase The percentage is over 70% A microcrystalline glass according to any one of claims 1 to 7.

9. The aforementioned microcrystalline glass is expressed in mol% based on oxide, SiO ２ The mole percentage of is 61.50% to 63.30%, and / or P ２ O ５ The mole percentage of is 1.20% to 1.91%, and / or Na ２ The mole percentage of O is 1.85% to 3.05%, and / or B ２ O ３ The mole percent of is 0 to 0.65%, and / or ZrO ２ The molar percentage of is 4.20% to 4.80%, and / or Li ２ The mole percentage of O is between 25.52% and 26.52%. A microcrystalline glass according to any one of claims 1 to 7.

10. The aforementioned microcrystalline glass is expressed in mol% based on oxide, SiO ２ The mole percentage of is 62.00% to 62.60%, and / or P ２ O ５ The mole percentage of is 1.30% to 1.60%, and / or Na ２ The molar percentage of O is 2.20% to 3.00%, and / or Li ２ The mole percentage of O is between 25.52% and 26.00%. A microcrystalline glass according to any one of claims 1 to 7.

11. The degree of crystallinity of the microcrystalline glass is 45% or more, and / or In the aforementioned microcrystalline glass, the average grain size is 100 nm or less. A microcrystalline glass according to any one of claims 1 to 7.

12. The microcrystalline glass is transparent in the visible light wavelength range and / or has a thickness of 0.7 mm, and the haze of the microcrystalline glass is less than 0.30%. A microcrystalline glass according to any one of claims 1 to 7.

13. The thickness is 0.70 mm, and the transmittance of the microcrystalline glass for light with a wavelength of 550 nm is 90.00% or more. The microcrystalline glass according to feature 12.

14. The Young's modulus of the microcrystalline glass is 100 GPa or more, and / or The Vickers hardness of the aforementioned microcrystalline glass is 640 kgf / mm². ２ That's all. A microcrystalline glass according to any one of claims 1 to 7.

15. A chemically strengthened microcrystalline glass, prepared from the microcrystalline glass described in claim 1 by a chemical strengthening treatment, The composition of the central part or tensile stress layer of the chemically strengthened microcrystalline glass is the same as the composition of the microcrystalline glass. The chemically strengthened microcrystalline glass includes a compressive stress layer region extending from the surface of the chemically strengthened microcrystalline glass to the compression depth, and has tensile stress within the chemically strengthened microcrystalline glass. Chemically strengthened microcrystalline glass characterized by the following features.

16. The chemically strengthened microcrystalline glass has a CT_LD of 45,000 to 55,000 MPa / mm, where CT_LD is the tensile stress linear density, and / or The chemically strengthened microcrystalline glass has a DOL_0 of 0.18t to 0.25t, where DOL_0 is the depth of the compressive stress layer and t is the thickness of the chemically strengthened microcrystalline glass, and / or The chemically strengthened microcrystalline glass has a CS_50 of 150 to 199 MPa, where CS_50 is the compressive stress value at a depth of 50 μm from the main surface of the chemically strengthened microcrystalline glass, and / or The chemically strengthened microcrystalline glass has |CT_AV| of 80 to 98 MPa, where |CT_AV| is the absolute value of the mean tensile stress, and / or The chemically strengthened microcrystalline glass has a |CT_CV| of 115 to 142 MPa, where |CT_CV| is the absolute value of the maximum tensile stress. The chemically strengthened microcrystalline glass according to feature 15.

17. The Vickers hardness of the aforementioned chemically strengthened microcrystalline glass is 680 kgf / mm². ２ That's all. A chemically strengthened microcrystalline glass according to any one of claims 15 to 16.

18. Includes the chemically strengthened microcrystalline glass described in claim 15 An electronic device characterized by the following features.

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