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

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] The present application relates to the technical field of microcrystalline glass, and in particular to microcrystalline glass, chemically strengthened microcrystalline glass, cover glass, and electronic devices.

[0002] Cross-reference to related applications This application claims priority based on a Chinese application bearing application number 202410175049.4 and entitled "Microcrystalline Glass, Chemically Strengthened Microcrystalline Glass, Cover Glass and Electronic Devices" filed with the China Patent Office on February 7, 2024, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Microcrystalline glass is a solid composite material made by controlling the precipitation of crystals during the heat treatment of a substrate glass. It contains a microcrystalline phase and a glass phase. Compared to glass materials that do not contain a microcrystalline phase, microcrystalline glass usually 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 propagation, allowing more impact energy to be consumed 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, such as display cover glass and back cover glass for electronic devices. Display cover glass for electronic devices generally requires good optical properties, as well as thin thickness and high mechanical properties. To further improve the mechanical properties of microcrystalline glass, it is usually necessary to perform a chemical strengthening treatment on the microcrystalline glass. Ion exchange produces chemically strengthened microcrystalline glass with high stress levels, high mechanical strength, and high damage resistance.

[0005] Therefore, how to improve the chemical strengthening effect of microcrystalline glass while maintaining excellent optical properties, or how to quickly and efficiently prepare chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties, are technical problems that those skilled in the art must solve as soon as possible. Summary of the Invention

[0006] The difficulty of chemical strengthening varies depending on the structure of microcrystalline glass and the structure of 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 optical properties required for cover glass applications, practitioners typically perform long-term chemical strengthening treatments on conventional microcrystalline glass or chemical strengthening treatments using molten salt at high temperatures (e.g., above 480°C). However, extending the strengthening time or increasing the molten salt temperature increases the cost of chemically strengthening microcrystalline glass, which in turn increases the cost of producing high-strength chemically strengthened microcrystalline glass.

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

[0008] To achieve the above objectives, the present application provides the following technical solutions:

[0009] In a first aspect, a microcrystalline glass is provided, the microcrystalline glass including a lithium disilicate (lithium disilicate) crystalline phase having a weight percentage higher than other crystalline phases present in the microcrystalline glass, and the components of the microcrystalline glass, expressed in mole percent on an oxide basis, are SiO2: 61.50% to 63.40%, Al2O3: 2.75% to 2.99%, and P2O5: 0.91% to 1.00%. 0.91%, ZrO2: 4.20% to 4.85%, Na2O: 1.80% to 3.20%, B2O3: 0 to 1.00%, Li2O: 25.32% to 26.52%, and 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] are expressed as Z = -1.344 × (2.65 - 100 × [Na2O]) 2 +0.466×100×[B2O3]+1.203×100×[ZrO2], and satisfy the relationship 4.80≦Z≦5.35, preferably 4.98≦Z≦5.20.

[0010] By giving microcrystalline glass a specific composition and crystalline phase structure, by setting the content of each component of the microcrystalline glass and the blending ratio of the content of each component within a specific range, by setting Na2O, B2O3, ZrO2, and Li2O in a specific mole percent relationship, and by making the main crystalline phase of the microcrystalline glass lithium disilicate, it is possible to impart excellent optical properties and high intrinsic strength to the microcrystalline glass, and by using the microcrystalline glass, it is possible to quickly and efficiently prepare chemically strengthened microcrystalline glass having a high stress level and high mechanical strength properties under the conditions of a normal chemical strengthening process.

[0011] In some embodiments, the molar percentages of NaO [NaO] and BO in the composition of the microcrystalline glass satisfy the relationship 0.90%≦[NaO]−[BO]≦3.10%, preferably 1.25%≦[NaO]−[BO]≦3.02%, and more preferably 2.00%≦[NaO]−[BO]≦3.00%.

[0012] In some embodiments, the molar percentages of NaO [NaO] and LiO [LiO] in the composition of the microcrystalline glass satisfy the relationship 8.55≦[LiO] / [NaO]≦13.85, preferably 8.55≦[LiO] / [NaO]≦11.50.

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

[0014] In some embodiments, the microcrystalline glass has, expressed as mole percent on an oxide basis, the mole percent of SiO2 is 61.50% to 63.30%, preferably 62.00% to 62.60%, and / or the mole percent of P2O5 is 1.20% to 1.91%, preferably 1.30% to 1.60%, and / or the mole percent of Na2O is 1.85% to 3.05%, preferably 2.20% to 3.00%, and / or the mole percent of B2O3 is 0 to 0.65%, and / or the mole percent of ZrO2 is 4.20% to 4.80%, and / or the mole percent of Li2O is 25.52% to 26.52%, preferably 25.52% to 26.00%.

[0015] In some embodiments, the microcrystalline glass has, expressed as mole percent on an oxide basis, SiO2 mole percent of 62.88%, 63.30%, 62.50%, 63.26%, 62.38%, 62.27%, 62.45%, 62.22%, or 63.17%, and / or Al2O3 mole percent of 2.86%, 2.87%, 2.93%, 2.94%, or 2.99%, and / or P2O5 mole percent of 1.00%, 1.20%, 1.30%, 1.60%, 1.40%, 1.41%, 1.53%, or and / or the mole % of ZrO2 is 4.80%, 4.74%, 4.84%, 4.33%, 4.34%, or 4.35%, and / or the mole % of Na2O is 1.85%, 2.35%, 1.95%, 2.36%, 2.96%, 3.01%, 2.93%, or 2.95%, and / or the mole % of Li2O is 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, expressed as oxide mole percent, of the formula Z is 5.19, 5.10, 5.09, 5.06, or 5.13; and / or the value of [NaO]-[BO] is 1.26%, 1.79%, 0.96%, 2.36%, 2.96%, 3.01%, 2.93%, or 2.95%; and / or the value of [LiO] / [NaO] is 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% to 85%, more preferably 55% to 65%, and / or the average crystal grain size of the microcrystalline glass is 100 nm or less, preferably 40 nm or less, more preferably 15 to 30 nm.

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

[0019] In some embodiments, at a thickness of 0.70 mm, the microcrystalline glass has a b-value of 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 more, preferably 105 to 112.50 GPa, and / or the Vickers hardness of the microcrystalline glass is 640 kgf / mm 2 More than 640 to 680 kgf / mm 2 is.

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

[0022] In some embodiments, the microcrystalline glass is prepared by subjecting a substrate glass to heat treatment, and preferably the heat treatment process includes a nucleation treatment and / or a crystallization treatment, and preferably the crystallization treatment includes a one-stage crystallization treatment or a two-stage crystallization treatment, and preferably when the curved microcrystalline glass is prepared 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 treatment, and performing secondary crystallization during the three-dimensional hot bending treatment process.

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

[0024] In a second aspect, a chemically strengthened microcrystalline glass is provided, the chemically strengthened microcrystalline glass being prepared by a chemical strengthening process from the microcrystalline glass described in any of the embodiments of the first aspect. The chemically strengthened microcrystalline glass has a central portion having the same composition as the microcrystalline glass described in any of the embodiments of the first aspect, includes a compressive stress layer region extending from the surface to the compression depth, and has tensile stress therein. 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 that has a weight percentage higher than other crystalline phases present in the chemically strengthened microcrystalline glass, and the components of the core of the chemically strengthened microcrystalline glass, expressed in mole percent on an oxide basis, are SiO2: 61.50% to 63.40%, Al2O3: 2.75% to 2.99%, and P2O5: 0.91% to 1.91%. , ZrO2: 4.20% to 4.85%, Na2O: 1.80% to 3.20%, B2O3: 0 to 1.00%, Li2O: 25.32% to 26.52%, and in the composition of the core of the chemically strengthened microcrystalline glass, the molar percentage of Na2O [Na2O], the molar percentage of B2O3 [B2O3], and the molar percentage of ZrO2 [ZrO2] are expressed as Z = -1.344 × (2.65 - 100 × [Na2O]) 2 +0.466×100×[B2O3]+1.203×100×[ZrO2], and satisfy the relationship 4.80≦Z≦5.35, preferably 4.98≦Z≦5.20.

[0026] In some embodiments, the molar percentages of NaO (NaO) and BO (BO) in the composition of the chemically strengthened microcrystalline glass core satisfy the relationship 0.90%≦[NaO]−[BO]≦3.10%, preferably 1.25%≦[NaO]−[BO]≦3.02%, and more preferably 2.00%≦[NaO]−[BO]≦3.00%; and / or the molar percentages of NaO (NaO) and LiO (LiO) in the composition of the chemically strengthened microcrystalline glass core satisfy the relationship 8.55≦[LiO] / [NaO]≦13.85, and preferably 8.55≦[LiO] / [NaO]≦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 DOL_0 of 150 to 190t. The chemically strengthened microcrystalline glass has a CS_50 of 9 MPa, preferably 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 120 to 140 MPa, where |CT_CV| is the absolute value of the maximum tensile stress.

[0028] In some embodiments, the chemically strengthened microcrystalline glass has a Vickers hardness of 680 kgf / mm 2 More than 700 kgf / mm 2 ~800kgf / mm 2 is.

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

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

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

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

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

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

[0035] In some embodiments, the electronic device further includes a camera element built into the housing, the housing including a camera protective cover provided over the camera element, the camera protective cover including the microcrystalline glass described in any of the embodiments of the first aspect or the chemically strengthened microcrystalline glass described in any of the embodiments of the second aspect.

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

[0037] In some embodiments, the housing can be made partially or entirely of microcrystalline glass or chemically strengthened microcrystalline glass. In the electronic device according to the present application, a portion of the display cover, back cover, camera protective cover, and intermediate frame can be made of the microcrystalline glass described in any of the embodiments of the first aspect or the chemically strengthened microcrystalline glass described in any of the embodiments of the second aspect.

[0038] One or more of the above technical solutions of the present application have the following advantages:

[0039] According to the present application, by providing microcrystalline glass with a specific composition and crystalline phase structure, by defining the content and ratio of each component in the microcrystalline glass within specific ranges, by defining NaO, BO, ZrO, and LiO in specific mole percent relationships, and by defining lithium disilicate as the primary crystalline phase of the microcrystalline glass, it is possible to provide the microcrystalline glass with excellent optical properties and high intrinsic strength. 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 under conventional chemical strengthening process conditions. This effectively reduces the production costs of high-strength chemically strengthened microcrystalline glass.

[0040] In order to more clearly explain the technical solutions of the embodiments in this application, the drawings necessary for explaining the embodiments will be briefly described below. The drawings described only illustrate some embodiments of this application and do not limit the scope. Those skilled in the art can obtain other related drawings based on these drawings without using inventive abilities. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is an XRD pattern of the microcrystalline glass according to Example 2. [Figure 2] 1 shows a transmittance curve of the microcrystalline glass according to Example 2 in the wavelength range of 360 nm to 740 nm. [Figure 3] FIG. 1 is a comparison diagram of XRD patterns of the microcrystalline glass according to Example 2 before and after chemical strengthening. [Figure 4] 1 is an actual image of the microcrystalline glass according to Example 2. [Figure 5] 1 is an actual image of the microcrystalline glass according to Example 7. [Figure 6] 1 is an actual image of the microcrystalline glass according to Comparative Example 5. [Figure 7] 1 is an actual image of the microcrystalline glass according to Comparative Example 6. [Figure 8] 1 is an actual image of the microcrystalline glass according to Comparative Example 8. [Figure 9] 1 is a schematic configuration diagram of the front of an electronic device according to an embodiment of the present application. [Figure 10] FIG. 1 is a schematic diagram illustrating the rear configuration of an electronic device according to an embodiment of the present application. [Figure 11] 1 is a schematic configuration diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0042] The technical solutions of the present application are described in detail below using examples, but the following examples are merely for the purpose of illustrating the present application and should not be considered as limiting the scope of the present application. In the examples, specific conditions are not specified, and the experiments can be carried out under conventional conditions or under conditions recommended by the manufacturer. For reagents or equipment used without specifying the manufacturer, conventional commercially available products can be used.

[0043] The endpoints of ranges and any values ​​disclosed herein are not limited to the exact range or value, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. Numerical ranges can be combined with each other between the endpoints of each range, or between the endpoints of each range and a single point, or between a single point, to create one or more new numerical ranges, and these numerical ranges should also be considered to be specifically disclosed herein. The terms "any" and "either" mean inclusive or exclusive (or may be present or absent). As used herein, "and / or" is inclusive; for example, "A and / or B" means that only A is present, or only B is present, or both A and B are present.

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

[0045] In this application, microcrystalline glasses are solid composite materials containing both a glass phase and a crystalline phase (also called a microcrystalline phase), and are also called glass-ceramics or glass-ceramics.

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

[0047] In this application, the substrate glass is glass that has not been subjected to nucleation treatment, crystallization treatment, and strengthening treatment, and is also called raw glass.

[0048] In this application, the composition of the core of chemically strengthened microcrystalline glass refers to the composition of the center or its vicinity in the depth or thickness of the chemically strengthened microcrystalline glass, i.e., the composition of the region of the chemically strengthened microcrystalline glass where ion exchange does not occur. Furthermore, the composition of the core of chemically strengthened microcrystalline glass is the same or nearly the same as the composition of microcrystalline glass that has not been subjected to the chemical strengthening treatment used to prepare the 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 the percentage of transmitted light that deviates from the incident light by 2.5° or more.

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

[0052] In this application, a major surface is the surface of a glass block or glass sheet that has the largest surface area, for example, the top or bottom surface of a horizontally oriented microcrystalline glass sheet.

[0053] In this application, crystallinity is the percentage of the total mass of crystalline phases or crystals in the microcrystalline glass relative to the mass of the microcrystalline glass, also referred to as the total content of crystalline phases in the microcrystalline glass.

[0054] In this application, when a major surface of a microcrystalline glass is irradiated with light of a certain wavelength, 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 is a light source with a color temperature of 6500K, a color rendering index Ra of greater than 90, and a broad spectral distribution in the visible light wavelength range for measuring the color of an object by irradiating it with daylight including the ultraviolet range.

[0056] In this application, a crystallized glass material is a glass material that has been heat treated for a certain period of time to reach a certain degree of crystallinity, but not to the target degree of crystallinity, and that can continue to crystallize and reach the target degree of crystallinity upon application of heat.

[0057] In this application, CT_LD is the tensile stress linear density, expressed in units of MPa / mm. Furthermore, after microcrystalline glass is ion-exchanged in 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. For example, during chemical strengthening, small-radius alkali metal ions in the microcrystalline glass are replaced with large-radius alkali metal ions in the molten salt, forming a compressive stress layer on the surface of the microcrystalline glass and a tensile stress layer inside the microcrystalline glass. In other words, chemically strengthened microcrystalline glass including a compressive stress layer and a tensile stress layer is prepared. In this application, CT_LD is calculated using the following formula:

[0058]

number

[0059] where t is the thickness of the chemically strengthened microcrystalline glass in mm, DOL_0 is the depth of the compressive stress layer in μm, and |CT_AV| is the absolute value of the average tensile stress in MPa. The tensile stress linear density formula can be calculated by substituting values ​​according to the above unit requirements, but the units are not involved in the calculation.

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

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

[0062] In this application, |CT_CV| is the absolute value of the maximum tensile stress, expressed in MPa, specifically the absolute value of the maximum value of all tensile stresses in the tensile stress layer, as 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 major surface of the chemically strengthened microcrystalline glass to the point where the compressive stress becomes zero near this surface, as measured by the SLP-2000 stress meter.

[0064] In this application, the above stress characteristics are measured using an SLP-2000 stress meter to measure |CT_CV|, DOL_0, and |CT_AV| of chemically strengthened microcrystalline glass. The relevant parameters of the stress meter are set as follows: the light source wavelength 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 tensile stress linear density (CT_LD) of the chemically strengthened microcrystalline glass is then calculated using the above formula for tensile stress linear density.

[0065] In this application, the b value represents the blue / yellow value of a 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 one of the scales for expressing the hardness of a material, which was devised in 1921 by Robert L. Smith and George E. Sandland of Vickers Ltd. in the UK.

[0067] In this application, the Vickers hardness measurement method is as follows. A microcrystalline glass or chemically strengthened microcrystalline glass sheet measuring 50 mm long, 50 mm wide, and 0.70 mm thick was selected as the test sample. The glass sample had a clean surface and no visible damage, such as scratches, dents, or cracks. The Vickers hardness was measured using a Vickers hardness tester. The Vickers hardness tester used in this application was a VTD405 low-load digital display Vickers hardness tester manufactured by Beijing Science and Technology Co., Ltd. The test conditions were a load of 300 gf, a loading time of 10 seconds, and the indentation validity met the standards of "GB / T37900-2019 Low-Load Vickers Hardness Indentation Method for Ultra-Thin Glass Hardness and Fracture Toughness Test Method." Three different measurement locations were selected on the surface of each test sample, and the average of the three measurement results was 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 an external force. In this application, the Young's modulus of microcrystalline glass is measured ultrasonically using a UMS-100 ultrasonic material characterization system.

[0069] In this application, nucleation refers to the formation of small crystal nuclei from nucleating materials in a substrate glass by heat treatment, and crystallization refers to the process of precipitating specific or targeted crystals from a glass substrate by heat treatment.

[0070] In this application, the thickness of the microcrystalline glass is measured using a micrometer. Furthermore, when ion exchange is performed, the overall increase in mass due to the 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 the thickness is approximately unchanged. In other words, the change in 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 the present application, the crystalline phase, crystallinity, and average crystal grain size of the microcrystalline glass or chemically strengthened microcrystalline glass are measured by XRD, and are specifically as follows:

[0073] (1) XRD test: The microcrystalline glass or chemically strengthened microcrystalline glass according to the present invention was crushed and polished to a sample with a particle size of less than 75 μm. The obtained sample was measured using an XRD diffractometer to obtain XRD peak curves and XRD diffraction data. The XRD 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 40 kV, an operating current of 30 mA, and 2θ = 10°-50°.

[0074] (2) Confirmation of crystalline phase: The 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 known as the total content of crystalline phases): The XRD test results (raw format) were imported into Jade, a Rietveld analysis software for X-ray diffraction data, and fitting and calculation were performed to confirm the crystallinity of the sample. Specifically, the ratio of the fitted peak area of ​​the crystalline phase to the fitted total peak area was taken as the crystallinity of the sample.

[0076] (4) Determination of average grain size (also referred to as mean crystal size): Using the data obtained from the XRD test, the average grain size of the sample can be calculated according to Scherrer's equation, D = Kλ / (β cos θ). Here, λ is the X-ray wavelength, λ = 0.154056 nm, β is the half-width 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 software Jade. Based on the angle 2θ and peak FWHM values ​​corresponding to each diffraction peak in the fitting results output by Jade, the peak FWHM value was converted to radians, giving β = (FWHM / 180 × 3.14). The crystal size of each diffraction peak was then calculated using the Scherrer equation, D = Kλ / (β cos θ), and averaged to determine the average grain size of the sample.

[0077] In this application, the transmittance, haze, and b-value of the microcrystalline glass according to the present application were measured using a haze meter in accordance with the national standard "GB / T7962.12-2010 Measurement Methods for Colorless Optical Glasses, Part 12: Spectral Transmittance." Specifically, the transmittance, haze, and b-value of five microcrystalline glass sheets from the same lot at different wavelengths were measured using a haze meter, and the average b-values ​​and haze values ​​of the five microcrystalline glass sheets were taken as the b-value and haze of the microcrystalline glass, respectively. The average transmittance of the five microcrystalline glass sheets 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 of this application is a spectrophotometer CM-3600A manufactured by Konica Minolta Japan, with a transmission type light receiving optical system, a plane diffraction grating as the spectroscopic means, a wavelength range of 360 nm to 740 nm, a wavelength interval of 10 nm, four pulse xenon lamps as the illumination light source, an ambient temperature of 24°C, and an air humidity of 40%.

[0078] In this application, the average drop height of the chemically strengthened microcrystalline glass samples in the sandpaper drop test was calculated by adding up the drop heights of each sample for the same Example or Comparative Example and dividing the total by the number of samples. 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] 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 of the sandpaper drop test for a single sample is as follows.

[0082] Step 1: Affix 80-mesh sandpaper to the underside of the 181g model, and then place the model on the LT-SKDL-CD drop device manufactured by Midorizusha.

[0083] Step 2: Place the chemically strengthened microcrystalline glass sample under test directly below the model machine, facing the sandpaper. Specifically, the main surface of the chemically strengthened microcrystalline glass should face the sandpaper. The model machine is dropped from a certain height, colliding with the chemically strengthened microcrystalline glass sample directly below it. If no cracks appear in the chemically strengthened microcrystalline glass sample, the model machine is dropped from a certain height, and the model machine is continued to be dropped until the chemically strengthened microcrystalline glass sample is broken. For example, the model machine is dropped from a height of 0.4 m, colliding with the sample once. If no cracks appear in the sample, the height is increased by 0.1 m, and the above process is repeated until the chemically strengthened microcrystalline glass sample is broken.

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

[0085] Without being bound by any theory, it is believed that chemical strengthening of microcrystalline glass involves ion exchange between alkali metal ions in the glass phase and those in the molten salt, resulting in the formation of a compressive stress structure on the surface of the microcrystalline glass, further improving the mechanical strength and damage resistance of the microcrystalline glass. The dense crystalline structure of microcrystalline glass contributes to the improvement of its intrinsic strength and damage resistance. However, the interconnected structure formed by the dense crystal grains in the microcrystalline glass encapsulates the glass phase (also known as the residual glass phase) between the crystal grains, blocking the ion exchange pathways and inhibiting the ion exchange between the alkali metal ions in the glass phase and those in the chemical strengthening molten salt. This makes it difficult to achieve high-stress properties through chemical strengthening of microcrystalline glass, i.e., to prepare high-strength chemically strengthened microcrystalline glass. In particular, lithium aluminosilicate glass is prone to the precipitation of non-single crystalline phases, such as lithium disilicate, quartz, and lithium metasilicate, after heat treatment. Microcrystalline glasses with non-single crystalline phases have a high degree of crystallinity, but the higher the crystalline content, the greater the energy and time required for ion diffusion. Therefore, structures with non-single crystalline phases may make ion exchange in microcrystalline glasses more difficult.

[0086] In the prior art, in order to prepare chemically strengthened microcrystalline glass that meets the requirements for use, conventional microcrystalline glass is usually subjected to a long-term chemical strengthening treatment or a chemical strengthening treatment using a molten salt at a high temperature (e.g., above 480°C). However, the extended strengthening time and the increased strengthening molten salt temperature increase the cost of chemically strengthening microcrystalline glass, which in turn increases the cost of producing high-strength chemically strengthened microcrystalline glass.

[0087] In view of the above, the present application provides a microcrystalline glass that, unlike conventional techniques, has excellent optical properties and high intrinsic strength and is capable of rapid ion exchange to achieve a high stress level, in order to improve economic efficiency. The microcrystalline glass of the present application allows chemically strengthened microcrystalline glass with a high stress level, excellent mechanical strength properties, and excellent damage resistance to be rapidly and efficiently prepared under the conditions of a typical chemical strengthening process.

[0088] As described above, some embodiments of the present application provide microcrystalline glass. The microcrystalline glass includes a lithium disilicate crystalline phase (Li2SiO5) in a weight percentage higher than other crystalline phases present in the microcrystalline glass. The components of the microcrystalline glass, expressed in mole percent on an oxide basis, include SiO2: 61.50% to 63.40%, Al2O3: 2.75% to 2.99%, P2O5: 0.91% to 1.91%, ZrO2: 4.20% to 4.85%, Na2O: 1.85% to 3.20%, BO3: 0 to 1.00%, and Li2O: 25.32% to 26.52%.

[0089] In the composition of the microcrystalline glass, the molar percentages of Na2O [Na2O], B2O3 [B2O3], and ZrO2 [ZrO2] are expressed as Z = -1.344 × (2.65 - 100 × [Na2O]) 2 +0.466×100×[B2O3]+1.203×100×[ZrO2], and satisfy the relationship 4.80≦Z≦5.35, preferably 4.98≦Z≦5.20.

[0090] The lithium disilicate (Li2SiO5) crystalline phase is an orthorhombic crystal based on an array of [SiO5] tetrahedra, and exhibits a flat or plate-like crystal shape. The lithium disilicate crystals within the microcrystalline glass have a randomly oriented interlocking microstructure, which distorts the crack propagation path and prevents crack expansion. This improves the strength and fracture toughness of the microcrystalline glass. Furthermore, lithium disilicate crystals have an optical refractive index close to that of a glass substrate (e.g., a substrate glass for preparing the microcrystalline glass of the present application), making them an ideal crystalline phase for preparing highly transparent microcrystalline glass. In the present application, the microcrystalline glass contains a structure in which lithium disilicate is the primary crystalline phase, contributing to the acquisition of high intrinsic strength and excellent optical properties.

[0091] According to the present application, by providing microcrystalline glass with a specific composition and crystalline phase structure, by defining the content and ratio of each component in the microcrystalline glass within specific ranges, by defining the molar ratios of NaO, BO, ZrO, and LiO within specific ranges, and by defining the primary crystalline phase of the microcrystalline glass as lithium disilicate, it is possible to impart excellent optical properties and high intrinsic strength to the microcrystalline glass, and by quickly and efficiently preparing chemically strengthened microcrystalline glass with high stress levels and high mechanical strength properties from the microcrystalline glass under conventional chemical strengthening process conditions, thereby effectively reducing the production costs of high-strength chemically strengthened microcrystalline glass.

[0092] The microcrystalline glass according to the present application can be prepared from a substrate glass by heat treatment. The composition of the microcrystalline glass, expressed in mole percent on an oxide basis, is the same as or nearly the same as the composition of the substrate glass used.

[0093] In the present application, SiO2 is an essential component necessary for forming the glass network structure and is one of the main components forming lithium disilicate crystals. The higher the SiO2 content, the denser the network structure of the glass phase, which in turn increases the mechanical strength of the microcrystalline glass, reduces the thermal expansion coefficient, and improves heat resistance, dielectric properties, and chemical stability. However, if the SiO2 content is too high, the melting temperature of the substrate glass increases, and the melt viscosity increases, which is disadvantageous for forming the substrate glass. Therefore, in the present application, to achieve both glass formability and excellent properties, the molar percentage of SiO2 in the substrate 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 the present application, the content of SiO in the base glass or microcrystalline glass, expressed in mole percent on an oxide basis, 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%, 62.30%, 62.40%, 62.50%, 62.60%, 62.70%, 62.80%, 62 ...10%, 62.20%, 62.30%, 62 %, 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 within a numerical range defined by any two of the specific values ​​above as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained in this application. 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 desired properties is obtained in this application.

[0095] In the present 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 the microcrystalline glass and promotes ion exchange to some extent during the chemical strengthening process. However, excessive Al2O3 increases the viscosity of the glass and tends to induce 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 substrate glass or microcrystalline glass in the present application is 2.75% to 2.99%.

[0096] In some embodiments of the present application, the Al2O3 content in the substrate glass or microcrystalline glass, expressed as mole percent 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 may be within a numerical range defined by any two of the specific values ​​listed above, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained. In specific embodiments, any of the above ranges may be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained.

[0097] In the present application, P2O5 acts as a nucleating agent to promote the uniform formation of glass crystal nuclei. If its content is too low or too high, crystallinity deteriorates, affecting the optical properties of the resulting microcrystalline glass and resulting in a decrease in the transparency of the microcrystalline glass. Therefore, in order to obtain the desired crystalline phase structure and achieve excellent optical properties and mechanical strength, the molar percentage of P2O5 in the substrate glass or microcrystalline glass in the present application 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 the present application, the content of P2O5 in the base glass or microcrystalline glass, expressed in mole percent 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 may be within a numerical range defined by any two of the above specific values ​​as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained. Additionally, in specific embodiments, any of the above ranges can be combined with any other ranges as long as the application results in a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties.

[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 nucleation agents for microcrystalline glass due to their high charge, strong electric field, and large concentration effect. However, too high a ZrO2 content can lead to phase separation in 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, the molar percentage of ZrO2 in the substrate glass or microcrystalline glass in this application is 4.20% to 4.85%, preferably 4.20% to 4.80%.

[0100] In some embodiments of the present application, the ZrO content of the substrate glass or microcrystalline glass, expressed as mole percent 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 may be within a numerical range defined by any two of the specific values ​​above, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained. In specific embodiments, any of the above ranges may be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained.

[0101] In the present application, Na2O is a network modifier oxide. An appropriate amount of Na2O supplies free oxygen, improves the viscosity of the glass, makes the glass easier to melt, promotes glass clarification, and can adjust the chemical strengthening rate. However, excessive Na2O not only reduces the crystallinity of the microcrystalline glass but also affects the chemical strengthening effect of the microcrystalline glass. Therefore, in order to improve the formability of the substrate glass and the chemical strengthening effect of the microcrystalline glass, the molar percentage of Na2O in the substrate glass or microcrystalline glass in the present application 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 the present application, the content of NaO in the base glass or microcrystalline glass, expressed in mole percent on an oxide basis, 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%, 2.70%, 2.75%, 2.80%, 2.85%, 2.90%, 2.95%, 3.00%, 3.05%, 3.10%, 3.15%, 3.20%, 3.25%, 3.30%, 3.35%, 3.40%, 3.45%, 3.50%, 3.55%, 3.60%, 3.65%, 3.70%, 3.85%, 3.90%, 3.95%, 4.00%, 4.05%, 4.10%, 4.15%, 4.20%, 4.25%, 4.30%, 4.35%, 4.40%, 4.45%, 4.50%, 4.55%, 4.60%, 4.65%, 4.70%, 4.85%, 4.90%, 4.95%, 5.00%, 5.05 ... %, 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 within a numerical range defined by any two of the specific values ​​above, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained in this application. 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 desired properties is obtained in this application.

[0103] In the present application, B2O3 acts as a flux to reduce the high-temperature viscosity of the glass, alleviating the problem of difficulty in melting due to ZrO2 and lowering the yield point temperature of the glass, but excessive B2O3 tends to deteriorate the transparency of the microcrystalline glass. Therefore, in order to improve the formability of the substrate glass and obtain microcrystalline glass with the desired properties, the molar percentage of B2O3 in the substrate glass or microcrystalline glass in the present application is 0 to 1.00%, preferably 0 to 0.65%.

[0104] In some embodiments of the present application, the B2O3 content of the substrate glass or microcrystalline glass, expressed as mole percent on an oxide basis, 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 may be within a numerical range defined by any two of the specific values ​​listed above, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained. In specific embodiments, any of the above ranges may be combined with any other range, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained.

[0105] In the present application, Li2O is a component necessary for the formation of the lithium disilicate crystalline phase, the primary crystalline phase, and is an essential component for supplying lithium ions for ion exchange during the chemical strengthening process. An appropriate amount of Li2O contributes to improving the glass viscosity, making the glass easier to melt, promoting glass clarification, and contributing to obtaining the desired content of lithium disilicate crystals. Furthermore, Li2O can provide alkali metal lithium ions for ion exchange with large-radius ions (e.g., sodium ions) in the molten salt, which is one of the factors affecting the stress level of chemically strengthened microcrystalline glass. However, excessive Li2O deteriorates the optical properties of the microcrystalline glass. Therefore, in order to improve the formability of the substrate glass, obtain a microcrystalline glass with a desired structure, and enhance the chemical strengthening effect of the microcrystalline glass, the mole percent of Li2O in the substrate glass or microcrystalline glass in the present application 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 the present application, the content of LiO in the base glass or microcrystalline glass, expressed in mole percent on an oxide basis, 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%, 26.40%, 26.45%, 26.46%, 26.47%, 26.48%, 26.49%, 26.50%, 26.51%, 26.52%, 26.53%, 26.54%, 26.55%, 26.56%, 26.57%, 26.58%, 26.59%, 26.60%, 26.61%, 26.62%, 26.63%, 26.64%, 26.65%, 26.66%, 26.67%, 26.68%, 26.69%, 26.70%, 26.71%, 26.72%, 26.73%, 26.74%, 26.75%, 26.76%, 26.77%, 26.78%, 26.79%, 26.80%, 26.85%, 26.86%, 26.87%, 26.88%, 26.89%, 26.90%, 26.95%, 26.91%, 26.92%, 26.93%, 26.94%, 26.95%, 26.95%, 26 %, 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 within a numerical range defined by any two of the specific values ​​above as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained in this application. 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 desired properties is obtained in this application.

[0107] In this application, adjusting and controlling the content range of each oxide component, and adjusting and controlling the compounding ratios between each oxide component, particularly the mole percent relationships between Na2O, BO3, ZrO2, and Li2O, contributes to obtaining microcrystalline glass with the desired crystalline phase structure and imparts excellent optical properties and high intrinsic strength to the microcrystalline glass. This also contributes to providing excellent chemical strengthening effects to the resulting microcrystalline glass, allowing chemically strengthened microcrystalline glass with high stress levels and high mechanical strength to be quickly and efficiently prepared from microcrystalline glass under standard chemical strengthening process conditions. This effectively reduces the production costs of high-strength chemically strengthened microcrystalline glass.

[0108] In some embodiments of the present application, the value of Z, which represents the mole percent relationship between NaO, BO, and ZrO 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 may be within a numerical range defined by any two of the specific values ​​listed above, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties. In specific embodiments, any of the above ranges may be combined with any other range, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties.

[0109] In some embodiments of the present application, the molar percentage of NaO [NaO] and the molar percentage of B2O3 [B2O3] in the composition of the substrate glass or microcrystalline glass satisfy the relationship 0.90%≦[NaO]−[B2O3]≦3.10%, preferably 1.25%≦[NaO]−[B2O3]≦3.02%, and more preferably 2.00%≦[NaO]−[B2O3]≦3.00%.

[0110] In some embodiments, the molar percentage difference between NaO 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%, 2.60%, 2.70%, 2.80%, 2.90%, 3.00%, 3.10%, 3.20%, 3.30%, 3.40%, 3.50%, 3.60%, 3.70%, 3.80%, 3.90%, 4.00%, 4.10%, 4.20%, 4.30%, 4.40%, 4.50%, 4.60%, 4.70%, 4.80%, 4.90%, 5.00%, 5.10%, 5.20%, 5.30%, 5.40%, 5.50%, 5.60%, 5.70%, 5.80%, 5.9 ... %, 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 within a numerical range defined by any two of the specific values ​​above as endpoints, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained in this application. 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 desired properties is obtained in this application.

[0111] In some embodiments of the present application, in the composition of the substrate glass or microcrystalline glass, the molar percentage of NaO [NaO] and the molar percentage of LiO [LiO] satisfy the relationship 8.55≦[LiO] / [NaO]≦13.85, preferably 8.55≦[LiO] / [NaO]≦11.50.

[0112] In some embodiments, the ratio of LiO to NaO (mol %) in the composition of the substrate glass or microcrystalline glass, [LiO] / [NaO], can 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, or can be any value within a numerical range defined by any two of the specific values ​​listed above, as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the desired properties is obtained. 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 desired properties is obtained.

[0113] In some embodiments of the present application, the composition of the substrate glass or microcrystalline glass may include other components in addition to the above composition ranges, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the required properties. For example, in some embodiments, the composition of the substrate glass or microcrystalline glass, expressed in mole percent on an oxide basis, may include CaO: 0.00 mol%-1.00 mol% and KO: 0.00 mol%-1.00 mol%.

[0114] As used herein, the terms "lithium disilicate crystalline phase has a higher weight percentage than other crystalline phases present in the microcrystalline glass," "lithium disilicate is the predominant crystalline phase," or similar expressions mean that the lithium disilicate crystalline phase accounts for 70 weight percent (wt%) or more of all crystalline phases in the microcrystalline glass according to embodiments of the present application. In some embodiments, the weight percent of the lithium disilicate crystalline phase is 70% or more, preferably 85% or more, of all crystalline phases in the microcrystalline glass. For example, the weight percent of the lithium disilicate crystalline phase of all crystalline phases in the microcrystalline glass 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 may be within a numerical range defined by any two of the specific values ​​above, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties. 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 has the desired properties.

[0115] In some embodiments of the present application, the crystallinity of the microcrystalline glass is 45% or more, preferably 45% to 85%, and more preferably 55% to 65%. A higher crystallinity of the microcrystalline glass is advantageous for achieving high impact resistance and high intrinsic strength. However, if the crystallinity is too high, it will affect the chemical strengthening effect of the microcrystalline glass, lengthening the chemical strengthening time required to obtain chemically strengthened microcrystalline glass with a high stress level and affecting the optical properties of the microcrystalline glass. In the present application, by providing the microcrystalline glass with the desired crystallinity, the microcrystalline glass can be endowed with excellent optical properties in addition to good impact resistance and high intrinsic strength, and its chemical strengthening effect can be improved.

[0116] In some embodiments of the present application, the crystallinity of the microcrystalline glass may be 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85%, or may be within a numerical range defined by any two of the specific values ​​above, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties. 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 has the desired properties.

[0117] In some embodiments of the present 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 contains a petalite crystalline phase, and preferably, the weight percentage of the microcrystalline glass occupied by the petalite crystalline phase may be 20% or less, more preferably 15% or less, 10% or less, or 5% or less. In some embodiments, it is preferred that the microcrystalline glass does not contain a petalite crystalline phase. Suppressing the precipitation of other crystalline phases contributes to the formation of a desired interlocking structure with lithium disilicate, ensuring that the microcrystalline glass has high mechanical strength properties, excellent optical properties, and damage resistance.

[0118] In some embodiments of the present application, the microcrystalline glass has an average crystal grain size of 100 nm or less, preferably 40 nm or less, and more preferably 15 to 30 nm. An appropriate average crystal grain size contributes to the microcrystalline glass achieving both excellent optical properties and high intrinsic strength. If the average crystal grain size is too high, the microcrystalline glass is likely to lose its transparency and the chemical strengthening effect will be affected. In the present application, having an appropriate average crystal grain size in the microcrystalline glass can impart to the microcrystalline glass not only good impact resistance and high intrinsic strength, but also excellent optical properties and improve its chemical strengthening effect.

[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 may be within a numerical range defined by any two of the specific values ​​above, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties. In specific embodiments, any of the above ranges may be combined with any other range, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties.

[0120] In some embodiments of the present application, the microcrystalline glass is transparent in the visible light wavelength range, and preferably has a transmittance of 90.00% or more, preferably more than 90.40%, for light with a wavelength of 550 nm when the thickness is 0.70 mm. Microcrystalline glass that satisfies this transmittance has good light transmittance and transparency, and is suitable for use in displays that require effective display. Here, "visible light wavelength range" refers to light with a wavelength of 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 may be a value within a numerical range defined by any two of the above specific values ​​as endpoints. In the present application, the transmittance of the microcrystalline glass may be, for example, 90% to 92%, 90.4% to 92%, etc., as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the required properties is obtained. In specific embodiments, any of the above ranges may be combined with any other range as long as a microcrystalline glass or chemically strengthened microcrystalline glass having the required properties is obtained.

[0122] In some embodiments of the present application, the haze of the microcrystalline glass at a thickness of 0.70 mm is less than 0.30%. Haze refers to cloudiness or opacity caused by light scattering within or on the surface of the microcrystalline glass. The lower the haze, the better the transparency and display effect of the microcrystalline glass. In some embodiments, the haze of the microcrystalline glass at 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 may be within a numerical range defined by any two of the above specific values, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the required properties. 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 has the required properties.

[0123] In some embodiments of the present application, the b-value of the microcrystalline glass when the thickness is 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 results are indicated as b(D65). The smaller the b-value, the better the display effect the microcrystalline glass will achieve. If the b-value is too large, the microcrystalline glass will exhibit undesirable colors, and the display effect of the glass will not meet the requirements for a display cover glass.

[0124] In some embodiments, the b-value of the microcrystalline glass at 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 may be within a numerical range defined by any two of the specific values ​​above, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties. 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 has the desired properties.

[0125] The microcrystalline glass of the present application has high transmittance, low haze, and a low b value, which indicates that the microcrystalline glass of the present application has excellent optical properties, uniformity, and transparency, and can meet the requirements for cover glass of electronic device displays.

[0126] In some embodiments of the present application, the Young's modulus of the microcrystalline glass is 100 GPa or more, preferably 105 to 112.50 GPa. By making the Young's modulus of the microcrystalline glass 100 GPa or more, the present application ensures a high-strength network structure of the microcrystalline glass, reduces the stress relaxation effect generated by ion exchange of the microcrystalline glass, and alleviates the inhibitory effect on deep stress in the combined compressive stress caused by factors such as high temperature and long time 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 may be within a numerical range defined by any two of the specific values ​​above, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties. 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 has the desired properties.

[0128] In some embodiments of the present application, the microcrystalline glass has a Vickers hardness of 640 kgf / mm 2 More than 640 to 680 kgf / mm 2 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 chemically strengthened microcrystalline glass having high mechanical strength properties and excellent damage resistance from the microcrystalline glass.

[0129] In some embodiments, the microcrystalline glass has a Vickers hardness of 640 kgf / mm 2 , 650kgf / mm 2 , 660kgf / mm 2 , 670kgf / mm 2 , 660.12kgf / mm 2 , 654.02kgf / mm 2 , 650.20kgf / mm 2 , 652.31kgf / mm 2 , 659.65kgf / mm 2 , 651.70kgf / mm 2 , 654.92, or 680 kgf / mm 2Alternatively, the present application may include a range of values ​​between any two of the specific values, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties. In specific embodiments, any of the above ranges may be combined with any other range, as long as the microcrystalline glass or chemically strengthened microcrystalline glass has the desired properties.

[0130] In some embodiments, the microcrystalline glass includes planar microcrystalline glass or curved microcrystalline glass. Preferably, when the microcrystalline glass is curved microcrystalline glass, the microcrystalline glass can be prepared by three-dimensional hot bending of a crystallized glass material with a crystallization degree of 5% or more. Without being bound by any theory, the present application uses a partially crystallized crystallized glass material, and three-dimensional hot bending is performed to continue thermal crystallization as the glass deforms until the target crystallization degree is reached. This allows for more accurate control of the amount of deformation after three-dimensional hot bending, reduces fluctuations in profile tolerance, and provides more stable dimensions, thereby improving the dimensional accuracy of the curved microcrystalline glass after hot bending. Those skilled in the art can select the crystallization degree of the partially crystallized glass material depending on the desired crystallization degree of the curved microcrystalline glass. For example, if the desired crystallinity of the curved microcrystalline glass is about 60%, a partially crystallized glass material with a crystallinity of 50% can be selected and subjected to hot bending to obtain a curved microcrystalline glass that meets the target crystallinity. In this application, the composition of the partially crystallized glass, expressed in mole percent based on oxides, is the same or approximately 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. Illustratively, 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 the microcrystalline glass have been described above. The method for preparing the microcrystalline glass will now be described in detail.

[0133] In this application, the preparation process of microcrystalline glass mainly includes the preparation process of substrate glass and the heat treatment process of the substrate glass.

[0134] In the present application, the substrate glass may be prepared by a conventional forming method, but is not limited thereto. For example, the forming method of the substrate glass includes, but is not limited to, a float method, an overflow method, a rolling method, and a casting method. For example, the substrate glass can be obtained by uniformly mixing each component according to a recipe, melt-forming the mixture, and then cooling and annealing the mixture.

[0135] For example, raw materials (raw materials commonly used in industry) are blended according to the proportions specified in the recipe, and a fining agent is added and 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, heated to a melting temperature of 1250°C to 1680°C, preferably 1480°C to 1680°C, and maintained at this temperature for 3 to 12 hours. The mixture is then cooled and molded in a mold, 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. The glass substrate is then cooled to room temperature while still in the furnace, yielding a glass substrate. Those skilled in the art can select the type and dosage of the fining agent according to their needs without using inventive skills. Furthermore, the fining agent may include, but is not limited to, one or more of sodium chloride, tin oxide, antimony oxide, arsenic oxide, etc. The amount of the fining agent added may be 0 to 1 wt% based on the total amount of the raw materials.

[0136] In some embodiments of the present application, the heat treatment process of the substrate glass may include a nucleation treatment and / or a crystallization treatment, but preferably includes a nucleation treatment and a crystallization treatment. 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 used to prepare 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 process, and then performing secondary crystallization during the three-dimensional hot bending process.

[0137] In some embodiments of the present application, the heat treatment of the substrate glass may be carried out in one stage or in two or more stages to provide the microcrystalline glass with the desired physical and chemical properties. When a one-stage heat treatment is carried out, a single-stage heating process is carried out directly without a separate nucleation process, and nucleation and crystal growth occur at the temperature reached in this single-stage heating process. In other words, a direct crystallization process is carried out. When a two-stage heat treatment is carried out, a two-stage heating process is carried out, including, but not limited to, a nucleation process, i.e., a nucleation process, followed by the desired crystal growth process, i.e., a crystallization process.

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

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

[0140] Some embodiments of the present application further provide a chemically strengthened microcrystalline glass, which is prepared from the above-described microcrystalline glass by chemical strengthening. The chemically strengthened microcrystalline glass has a central composition identical to that of the microcrystalline glass described in any of the above-described embodiments, includes a compressive stress layer region extending from the surface to the compression depth, and has tensile stress therein. That is, the chemically strengthened microcrystalline glass includes a compressive stress layer and a tensile stress layer.

[0141] Chemical strengthening, or ion exchange, involves impregnating microcrystalline glass in molten salt and exchanging the alkali metal ions with small ionic radii in the microcrystalline glass for alkali metal ions with large ionic radii in the molten salt, forming a compressive stress layer on the surface of the microcrystalline glass and resulting in chemically strengthened microcrystalline glass with superior mechanical properties.

[0142] Furthermore, the composition of the surface of the microcrystalline glass after chemical strengthening may differ from that of the as-formed microcrystalline glass (i.e., the microcrystalline glass before chemical strengthening and without ion exchange). This is because ion exchange replaces alkali metal ions (e.g., Li+ or Na+) on the surface of the as-formed microcrystalline glass with larger alkali metal ions (e.g., Na+ or K+). However, in embodiments, the composition and crystalline phase population at or near the center of the microcrystalline glass still have the composition and crystalline phase population of the as-formed microcrystalline glass. In other words, in the present application, the composition (e.g., the composition of the tensile stress layer) and crystalline phase population of the center of the chemically strengthened microcrystalline glass obtained by chemical strengthening are identical or nearly identical to those of the as-formed microcrystalline glass.

[0143] In some embodiments of the present application, the chemical strengthening treatment can be a one-stage strengthening method or a multi-stage strengthening method. The molten salt used in the chemical strengthening treatment is a molten salt containing a sodium salt and / or a potassium salt. Preferably, the molten salt used in the chemical strengthening treatment according to the present 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 the present application, the concentration of the potassium salt in the molten salt is preferably 0 wt% to 90 wt%, and the concentration of the sodium salt is preferably 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 the present 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 the present application, the chemically strengthened microcrystalline glass contains a lithium disilicate crystalline phase having a weight percentage higher than other crystalline phases present in the chemically strengthened microcrystalline glass, and the components of the core of the chemically strengthened microcrystalline glass, expressed in mole percent on an oxide basis, are SiO2: 61.50% to 63.40%, Al2O3: 2.75% to 2.99%, and P2O5: 0.91% to 1.9 1%, ZrO2: 4.20% to 4.85%, Na2O: 1.80% to 3.20%, B2O3: 0 to 1.00%, Li2O: 25.32% to 26.52%, and in the composition of the core of the chemically strengthened microcrystalline glass, the molar percentage of Na2O [Na2O], the molar percentage of B2O3 [B2O3], and the molar percentage of ZrO2 [ZrO2] satisfy the following relationship: Z = -1.344 × (2.65 - 100 × [Na2O]) 2 +0.466×100×[B2O3]+1.203×100×[ZrO2], and satisfy the relationship 4.80≦Z≦5.35, preferably 4.98≦Z≦5.20.

[0145] In some embodiments of the present application, the molar percentages of NaO [NaO] and BO in the composition of the core of the chemically strengthened microcrystalline glass satisfy the relationship 0.90%≦[NaO]−[BO]≦3.10%, preferably 1.25%≦[NaO]−[BO]≦3.02%, more preferably 2.00%≦[NaO]−[BO]≦3.00%, and / or the molar percentages of NaO [NaO] and LiO in the composition of the core of the chemically strengthened microcrystalline glass satisfy the relationship 8.55≦[LiO] / [NaO]≦13.85, preferably 8.55≦[LiO] / [NaO]≦11.50.

[0146] In some embodiments of the present 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 is sufficiently concentrated, ensuring a high surface stress level of the chemically strengthened microcrystalline glass and excellent damage resistance, such as drop resistance, that meets market demands.

[0147] In some embodiments, the CT_LD of the chemically strengthened microcrystalline glass may be 45,000 MPa / mm, 46,000 MPa / mm, 47,000 MPa / mm, 48,000 MPa / mm, 49,000 MPa / mm, 50,000 MPa / mm, 51,000 MPa / mm, 52,000 MPa / mm, 53,000 MPa / mm, 54,000 MPa / mm, 50,479 MPa / mm, 50,547 MPa / mm, 50,297 MPa / mm, 50,497 MPa / mm, 50,833 MPa / mm, 52,768 MPa / mm, or 55,000 MPa / mm, or may be within a numerical range defined by any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the required properties is obtained. 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 required properties is obtained.

[0148] In some embodiments of the present 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 offset the impact force. By ensuring that the chemically strengthened microcrystalline glass has a high surface stress level, it can offset more of the residual energy from drops, pressure, impacts, and collisions, ensuring its excellent damage resistance, 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 may be any value within a numerical range defined by any two of the above specific values, as long as the chemically strengthened microcrystalline glass has the required properties. In specific embodiments, any of the above ranges may be combined with any other range, as long as the chemically strengthened microcrystalline glass has the required properties.

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

[0151] In some embodiments, the |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 may be within a numerical range defined by any two of the above specific values, as long as the chemically strengthened microcrystalline glass has the required properties. In specific embodiments, any of the above ranges can be combined with any other range, as long as the chemically strengthened microcrystalline glass has the required properties.

[0152] In some embodiments of the present application, the chemically strengthened microcrystalline glass has a |CT_CV| of 115 to 142 MPa. |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 can offset more residual energy from drops, pressure, impacts, and collisions, thereby providing the chemically strengthened microcrystalline glass with excellent damage resistance.

[0153] In some embodiments, the |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 may be within a numerical range defined by any two of the above specific values, as long as the chemically strengthened microcrystalline glass has the required properties. In specific embodiments, any of the above ranges can be combined with any other range, as long as the chemically strengthened microcrystalline glass has the required properties.

[0154] In some embodiments of the present application, the chemically strengthened microcrystalline glass has a Vickers hardness of 680 kgf / mm 2 More than 700 kgf / mm 2 ~800kgf / mm 2 By setting the Vickers hardness of the chemically strengthened microcrystalline glass within the above range, it is possible to impart high hardness and high mechanical strength properties to the chemically strengthened microcrystalline glass, and to provide the glass with excellent damage resistance.

[0155] In some embodiments, the chemically strengthened microcrystalline glass has a Vickers hardness of 680 kgf / mm 2 , 690kgf / mm 2 , 700kgf / mm 2 , 710kgf / mm 2 , 720kgf / mm 2 , 730kgf / mm 2 , 740kgf / mm 2 , 750kgf / mm 2 , 760kgf / mm 2 , 770kgf / mm 2 , 780kgf / mm 2 , 790kgf / mm 2 , 726.25kgf / mm 2 , 723.96kgf / mm 2 , 724.50kgf / mm 2 , 720.31kgf / mm 2 , 730.98kgf / mm 2 , 718.60kgf / mm 2 , 731.57kgf / mm 2 , or 800 kgf / mm 2 Alternatively, the present application may include a range of values ​​between any two of the specific values, as long as the desired properties of the chemically strengthened microcrystalline glass are obtained. In specific embodiments, any of the above ranges may be combined with any other range, as long as the desired properties of the chemically strengthened microcrystalline glass are obtained.

[0156] In some embodiments of the present 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 ensuring that the chemically strengthened microcrystalline glass has an appropriate DOL_0, it is possible to prevent cracks from suddenly forming due to impact or penetration by a blunt or sharp object, which would directly penetrate the compressive stress region and reach the tensile stress region, thereby causing the microcrystalline glass to break. Therefore, the chemically strengthened microcrystalline glass has improved properties that offset the energy that would otherwise propagate cracks, ensuring excellent damage resistance, such as 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 may be within a numerical range defined by any two of the specific values, as long as the chemically strengthened microcrystalline glass has the desired properties. In specific embodiments, any of the above ranges may be combined with any other range, as long as the chemically strengthened microcrystalline glass has the desired properties. 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. Alternatively, the DOL_0 may be a value within a numerical range defined by any two of the above specific values ​​as endpoints, as long as a chemically strengthened microcrystalline glass having the required properties is obtained in this application.

[0158] In some embodiments of the present application, the microcrystalline glass or chemically strengthened microcrystalline glass may have a two-dimensional (2D), two.5-dimensional (2.5D), three-dimensional (3D), or irregular shape, and / or the microcrystalline glass or chemically strengthened microcrystalline glass may have a uniform or variable thickness. Those skilled in the art can select this according to their needs. Here, "variable thickness" means that the microcrystalline glass or chemically strengthened microcrystalline glass includes at least two portions with different thicknesses.

[0159] In the present application, the chemically strengthened microcrystalline glass is made to satisfy specific stress characteristics, so that the chemically strengthened microcrystalline glass has excellent mechanical strength properties, excellent mechanical strength properties, excellent damage resistance, and particularly excellent drop resistance.

[0160] In some embodiments of the present 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 allows the chemically strengthened microcrystalline glass of the present application to have 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, for example.

[0161] The microcrystalline glass or chemically strengthened microcrystalline glass of the present application, which has excellent properties, can be applied 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, smart watches, and smart glasses). Microcrystalline glass or chemically strengthened microcrystalline glass can also be applied to vehicles, aircraft, and other aircraft, as well as any glass component requiring microcrystalline glass. Examples include displays, cover glass, touchscreens, and glass inner screens or inner frames of electronic devices, as well as window glass such as windshields or side windows of vehicles, aircraft, and aircraft. Examples include 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, pillar surfaces, and counter surfaces. Storage containers include, but are not limited to, cups, plates, pill bottles, and beverage bottles.

[0162] For example, the microcrystalline glass or chemically strengthened microcrystalline glass having excellent properties according to the present application can be used to manufacture glass members. The glass members referred to herein can be ordered or irregular, and can be manufactured by those skilled in the art according to their needs.

[0163] For example, the microcrystalline glass or chemically strengthened microcrystalline glass having excellent properties according to the present application can be used to manufacture a cover glass. The cover glass may be a display cover, a back cover, or a camera protective cover for an electronic device. For example, the microcrystalline glass or chemically strengthened microcrystalline glass having excellent properties according to the present application can be used in an electronic device. As shown in FIGS. 9, 10, and 11, an embodiment of the present application provides an electronic device. The 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 attached to the outside of the electronic device and elements such as a circuit board and a battery housed inside the housing 1. The housing 1 includes a display cover 11 attached to the front and a back cover 12 attached to the back. The display cover 11 is attached to a display module 4. The display cover 11 and / or the back cover 12 can be made of the microcrystalline glass or chemically strengthened microcrystalline glass. In the embodiment of the present application, the display cover 11 and the back cover 12 may entirely or partially use the above-mentioned microcrystalline glass or chemically strengthened microcrystalline glass. In the embodiment of the present application, the display may be a touch display, and the display cover 11 may be a protective cover provided for the touch display. In the embodiment of the present application, the back cover 12 may cover only the back side of the electronic device (i.e., the side away from the display), or may cover both the back side and the side frame of the electronic device. Optionally, the back cover 12 may cover the entire side frame around the electronic device, or only some of the side frame.

[0164] In some embodiments of the present application, as shown in FIG. 10 , the electronic device further includes a camera element 2 built into the housing 1, and the housing 1 may include a camera protective cover 13 attached to the camera element 2 to protect the camera element 2. The camera protective cover 13 can be made of the above-described microcrystalline glass or chemically strengthened microcrystalline glass. In embodiments of the present application, the camera protective cover 13 may be made entirely or partially of the above-described microcrystalline glass or chemically strengthened microcrystalline glass. In embodiments of the present application, the camera protective cover 13 is provided at a position corresponding to the position of the camera element 2, and may be provided on the front or rear of the electronic device. In some embodiments of the present application, the camera protective cover 13 may be configured separately from the display cover 11 or the back cover 12. In another embodiment of the present application, the camera protective cover 13 may be configured integrally with the display cover 11 or the back cover 12.

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

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

[0167] In some embodiments of the present application, the display cover, back cover, camera protective 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 the present application, the display cover, back cover, camera protective cover, and intermediate frame of the electronic device may have a uniform thickness or a variably uniform 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 solution of the present application will be further described below with reference to examples. The examples of the present application described in detail below are merely illustrative for explaining the present application, and are not intended to limit the present application.

[0170] Example 1 (1) Preparation of substrate glass Each raw material (raw materials commonly used in industry) was blended according to the recipe shown in Table 1 until the total mass of the blended raw materials was 1000 g. 5 g of sodium chloride (NaCl) as a clarifier was added to the blended raw materials, and then 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 and melted in the platinum crucible at 1650°C for 5 hours, then placed in a mold to be cooled and shaped, and cooled to 900°C. It was then placed in an annealing furnace at 500°C and annealed for 24 hours, and then cooled to room temperature while still in the furnace to obtain a substrate 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 rate of 10°C / min for nucleation. After holding at this temperature for 4 hours, the temperature was again raised to 710°C at a rate of 10°C / min for crystallization. After holding at this temperature for 1.5 hours, the temperature was lowered to room temperature at a rate of 1°C / min to obtain a microcrystalline glass block sample. The prepared microcrystalline glass had the same composition as the substrate glass, expressed in mole percent based on oxides, as shown in Table 1.

[0173] The obtained microcrystalline glass block sample was subjected to the following cold processing steps: cutting, CNC machining (the CNC machine used in this application is model RCG500S), and polishing, to prepare a microcrystalline glass sample that met the desired specifications and requirements. In this application, the microcrystalline glass block sample was subjected to the above cold processing steps to prepare a microcrystalline glass sample with a thickness of 0.70 mm. Specifically, a polished sheet of microcrystalline glass sample measuring 50 mm x 50 mm x 0.70 mm was prepared.

[0174] The microcrystalline glass sample obtained in Example 1 was subjected to the following tests.

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

[0176] (3) Preparation of chemically strengthened microcrystalline glass The obtained microcrystalline glass sample was placed in a tempering furnace and preheated for 5 minutes, then immediately placed in molten salt at 460°C for chemical strengthening. The composition of the molten salt 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 two hours of chemical strengthening, the microcrystalline glass sample was removed and slowly cooled to room temperature in the tempering furnace. The salt on the surface of the microcrystalline glass was then washed with water, and the microcrystalline glass sample was dried to obtain chemically strengthened microcrystalline glass.

[0177] The chemically strengthened microcrystalline glass obtained in Example 1 was subjected to the following tests.

[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 the chemically strengthened microcrystalline glass was measured, and the results are shown in Table 3.

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

[0181] Examples 2 to 7 Each test 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, respectively.

[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] Fig. 2 shows the transmittance curve of the microcrystalline glass according to Example 2. As can be seen from Fig. 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 before and after chemical strengthening of the microcrystalline glass of Example 2. As can be seen from Figure 3, the crystalline phase structure of the microcrystalline glass does not change significantly before and after chemical strengthening, 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 sheets of Examples 2 and 7, respectively. The images were taken on a black background to show the state of the microcrystalline glass sheets. As can be seen from Figures 4 and 5, the microcrystalline glass of the present application is almost colorless and transparent due to its small b value, which allows for excellent display effects.

[0186] Comparative Examples 1 to 12 Each test 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, respectively.

[0187] Figures 6, 7, and 8 show actual images of the microcrystalline glass sheets of Comparative Example 5, Comparative Example 6, and Comparative Example 8, respectively. To show the state of the microcrystalline glass sheets, the images were taken on paper with a black background. As can be seen from Figures 6, 7, and 8, the microcrystalline glass sheets of Comparative Example 5 have a large b value, resulting in a clear bluish tint. The larger the b value, the more obvious the blue tint and the greater the impact on the display effect.

[0188] [Table 1]

[0189] Here, if the oxide content in Table 1 is "0," it means that the component was not actively or intentionally added to the glass composition in the initial raw material blending process, but may be present as an impurity. In this table, the content is expressed in mole percent based on the oxide and substituted into each formula, and the unit of mole is not involved in the calculation of the formula.

[0190] [Table 2]

[0191] [Table 3]

[0192] As can be seen from the examples and comparative examples in Tables 1-3 above, compared to the comparative examples, the examples of the present application control the composition and ratio of each component of the microcrystalline glass to satisfy the range of each oxide content, while controlling the mole percent relationships between Na2O, BO3, ZrO2, and Li2O to meet specific range requirements. Furthermore, by forming a microstructure in which lithium disilicate is the primary crystalline phase, the microcrystalline glass is endowed with 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). Furthermore, chemically strengthened microcrystalline glass with high stress levels and high mechanical strength can be rapidly and efficiently prepared under conventional chemical strengthening conditions. The chemically strengthened microcrystalline glass of the examples of the present application exhibits high CS_50, |CT_AV|, DOL_0, and CT_LD, and excellent drop resistance.

[0193] On the other hand, the glass compositions of Comparative Examples 1 to 12 do not simultaneously satisfy the range of oxide content and the molar percentage relationships between Na2O, BO3, ZrO2, and Li2O according to the present application. As a result, in each Comparative Example, the prepared microcrystalline glass exhibits poor optical properties, such as low transmittance and high optical b value and haze. Furthermore, under similar chemical strengthening process conditions, the chemically strengthened microcrystalline glass prepared exhibits inferior stress properties and poor drop resistance compared to the Examples. In other words, because the Comparative Examples do not simultaneously satisfy the requirements of the present application, they are unable to achieve both excellent optical properties and high stress levels.

[0194] The above examples are only specific examples of the present application and do not limit the present application. Those skilled in the art may have various modifications and variations to the present application. As long as they do not deviate from the spirit and principle of the present application, any modifications, equivalent substitutions, improvements, etc., fall within the scope of protection of the present application.

[0195] Industrial Applicability According to the present application, by providing microcrystalline glass with a specific composition and crystalline phase structure, by defining the content and ratio of each component in the microcrystalline glass within specific ranges, by defining NaO, BO, ZrO, and LiO in specific mole percent relationships, and by defining lithium disilicate as the primary crystalline phase of the microcrystalline glass, it is possible to provide the microcrystalline glass with excellent optical properties and high intrinsic strength. 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 under conventional chemical strengthening process conditions. This effectively reduces the production costs of high-strength chemically strengthened microcrystalline glass. [Explanation of symbols]

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

Claims

1. A microcrystalline glass, a lithium disilicate crystalline phase having a weight percentage greater than any other crystalline phase present in the microcrystalline glass; The components of the microcrystalline glass are, in mole percent on an oxide basis, SiO ２ :61.50%~63.40%, Al ２ O ３ :2.75%~2.99%, P ２ O ５ :0.91% to 1.91%, ZrO ２ :4.20%~4.85%, Na ２ O: 1.80% to 3.20%, B ２ O ３ :0~1.00%, Li ２ O: 25.32% to 26.52%, In the composition of the microcrystalline glass, Na ２ mol% of O [Na ２ O] and B ２ O ３ % by mole [B ２ O ３ ] and ZrO ２ mol% [ZrO ２ ]is Z=-1.344×(2.65-100×[Na ２ O]) 2 +0.466×100×[B ２ O ３ ]+1.203×100×[ZrO ２ ], satisfying the relationship of 4.80≦Z≦5.35, preferably 4.98≦Z≦5.

20. A microcrystalline glass characterized by:

2. In the composition of the microcrystalline glass, Na ２ mol% of O [Na ２ O] and B ２ O ３ % by mole [B ２ O ３ ]is 0.90%≦[Na ２ O]-[B ２ O ３ ]≦3.10%, preferably 1.25%≦[Na ２ O]-[B ２ O ３ ]≦3.02%, more preferably 2.00%≦[Na ２ O]-[B ２ O ３ ]≦3.00% 2. The microcrystalline glass according to claim 1 .

3. In the composition of the microcrystalline glass, Na ２ mol% of O [Na ２ O] and Li ２ mol% of O [Li ２ O] means 8.55≦[Li ２ O] / [Na ２ O]≦13.85, preferably 8.55≦[Li ２ O] / [Na ２ O]≦11.50 3. The microcrystalline glass according to claim 1 or 2.

4. Of all the crystalline phases of the microcrystalline glass, the weight percentage of the lithium disilicate crystalline phase is 70% or more, preferably 85% or more.

4. The microcrystalline glass according to claim 1, wherein the glass is a crystalline material.

5. The microcrystalline glass contains, in mole percent based on oxides, SiO ２ is from 61.50% to 63.30%, preferably from 62.00% to 62.60%, and / or P ２ O ５ is between 1.20% and 1.91%, preferably between 1.30% and 1.60%, and / or Na ２ the mole percent of O is between 1.85% and 3.05%, preferably between 2.20% and 3.00%, and / or B ２ O ３ and / or ZrO ２ is between 4.20% and 4.80%; and / or Li ２ The mole percentage of O is 25.52% to 26.52%, preferably 25.52% to 26.00%.

5. The microcrystalline glass according to claim 1, wherein the glass is a crystalline material.

6. The microcrystalline glass contains, in mole percent based on oxides, SiO ２ is 62.88%, 63.30%, 62.50%, 63.26%, 62.38%, 62.27%, 62.45%, 62.22%, or 63.17%; and / or Al ２ O ３ is 2.86%, 2.87%, 2.93%, 2.94%, or 2.99%; and / or P ２ O ５ is 1.00%, 1.20%, 1.30%, 1.60%, 1.40%, 1.41%, 1.53%, or 1.54%; and / or ZrO ２ is 4.80%, 4.74%, 4.84%, 4.33%, 4.34%, or 4.35%; and / or Na ２ the mole percent of O is 1.85%, 2.35%, 1.95%, 2.36%, 2.96%, 3.01%, 2.93%, or 2.95%, and / or Li ２ The mole percent of O is 25.62%, 25.82%, 25.69%, 25.36%, 25.77%, 25.87%, 25.90%, 25.79%, 26.03%, or 25.74% 5. The microcrystalline glass according to claim 1, wherein the glass is a crystalline material.

7. The composition of the microcrystalline glass is, in terms of oxide content in mole percent, the value of formula Z is 5.19, 5.10, 5.09, 5.06, or 5.13; and / or [Na ２ O]-[B ２ O ３ ] is 1.26%, 1.79%, 0.96%, 2.36%, 2.96%, 3.01%, 2.93%, or 2.95%, and / or [Li ２ O] / [Na ２ O] is 13.83, 10.93, 13.01, 10.92, 8.73, 8.61, 8.79, or 8.83 7. The microcrystalline glass according to claim 1, wherein the glass is a crystalline material.

8. The crystallinity of the microcrystalline glass is 45% or more, preferably 45% to 85%, more preferably 55% to 65%, and / or In the microcrystalline glass, the average crystal grain size is 100 nm or less, preferably 40 nm or less, and more preferably 15 to 30 nm.

8. The microcrystalline glass according to claim 1, wherein the glass is a crystalline material.

9. The microcrystalline glass is transparent in the visible light wavelength range, and preferably has a thickness of 0.70 mm and a transmittance of 90.00% or more, preferably more than 90.40%, for light with a wavelength of 550 nm; and / or has a thickness of 0.7 mm and a haze of less than 0.30%.

9. The microcrystalline glass according to claim 1.

10. The thickness is 0.70 mm, and the b value of the microcrystalline glass is less than 0.70, preferably 0.60 or less.

10. The microcrystalline glass according to claim 1.

11. The Young's modulus of the microcrystalline glass is 100 GPa or more, preferably 105 to 112.50 GPa, and / or The Vickers hardness of the microcrystalline glass is 640 kgf / mm ２ or more, preferably 640 to 680 kgf / mm ２ is The microcrystalline glass according to any one of claims 1 to 10.

12. The microcrystalline glass includes planar microcrystalline glass or curved microcrystalline glass. Preferably, when the microcrystalline glass is curved microcrystalline glass, the microcrystalline glass can be prepared by subjecting a crystallized glass material having a crystallinity of 5% or more to a three-dimensional hot bending process.

12. The microcrystalline glass according to claim 1.

13. The microcrystalline glass is prepared by subjecting a substrate glass to a heat treatment, and the heat treatment step preferably includes a nucleation treatment and / or a crystallization treatment. The crystallization treatment preferably includes a one-stage crystallization treatment or a two-stage crystallization treatment. When the curved microcrystalline glass is prepared by a two-stage crystallization treatment, the second crystallization treatment step preferably involves heating the crystallized glass material obtained in the first crystallization treatment step to a crystallization temperature and performing a three-dimensional hot bending process.

13. The microcrystalline glass according to claim 1.

14. A chemically strengthened microcrystalline glass, The composition of the central portion of the chemically strengthened microcrystalline glass is the same as the composition of the microcrystalline glass according to any one of claims 1 to 13, and the composition includes a compressive stress layer and a tensile stress layer. A chemically strengthened microcrystalline glass characterized by:

15. The chemically strengthened microcrystalline glass contains a lithium disilicate crystalline phase having a weight percentage higher than that of other crystalline phases present in the chemically strengthened microcrystalline glass, and the central component of the chemically strengthened microcrystalline glass contains, in mole percent on an oxide basis, SiO ２ :61.50%~63.40%, Al ２ O ３ :2.75%~2.99%, P ２ O ５ :0.91% to 1.91%, ZrO ２ :4.20%~4.85%, Na ２ O: 1.80% to 3.20%, B ２ O ３ :0~1.00%, Li ２ O: 25.32% to 26.52%, In the composition of the central part of the chemically strengthened microcrystalline glass, Na ２ mol% of O [Na ２ O] and B ２ O ３ % by mole [B ２ O ３ ] and ZrO ２ mol% [ZrO ２ ]is Z=-1.344×(2.65-100×[Na ２ O]) 2 +0.466×100×[B ２ O ３ ]+1.203×100×[ZrO ２ ], satisfying the relationship of 4.80≦Z≦5.35, preferably 4.98≦Z≦5.

20.

15. The chemically strengthened microcrystalline glass according to claim 14.

16. In the composition of the central part of the chemically strengthened microcrystalline glass, Na ２ mol% of O [Na ２ O] and B ２ O ３ % by mole [B ２ O ３ ]is 0.90%≦[Na ２ O]-[B ２ O ３ ]≦3.10%, preferably 1.25%≦[Na ２ O]-[B ２ O ３ ]≦3.02%, more preferably 2.00%≦[Na ２ O]-[B ２ O ３ ]≦3.00%, and / or In the composition of the central part of the chemically strengthened microcrystalline glass, Na ２ mol% of O [Na ２ O] and Li ２ mol% of O [Li ２ O] means 8.55≦[Li ２ O] / [Na ２ O]≦13.85, preferably 8.55≦[Li ２ O] / [Na ２ O]≦11.50 16. The chemically strengthened microcrystalline glass according to claim 14 or 15.

17. 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 CS_50 of 150 to 199 MPa, preferably 160 to 199 MPa, where CS_50 is a 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. The chemically strengthened microcrystalline glass according to any one of claims 14 to 16.

18. The Vickers hardness of the chemically strengthened microcrystalline glass is 680 kgf / mm ２ More than 700 kgf / mm ２ ~800kgf / mm ２ is The chemically strengthened microcrystalline glass according to any one of claims 14 to 17.

19. The microcrystalline glass according to any one of claims 1 to 13 or the chemically strengthened microcrystalline glass according to any one of claims 14 to 18 is included. A cover glass characterized by:

20. The microcrystalline glass according to any one of claims 1 to 13 or the chemically strengthened microcrystalline glass according to any one of claims 14 to 18 is included. An electronic device characterized by:

21. The electronic device includes a housing attached to the outside of the electronic device and a circuit board built into the housing, and the housing includes the microcrystalline glass according to any one of claims 1 to 13 or the chemically strengthened microcrystalline glass according to any one of claims 14 to 18.

21. The electronic device according to claim 20.

22. The housing includes a display cover attached to a front surface of the electronic device, and the display cover includes the microcrystalline glass according to any one of claims 1 to 13 or the chemically strengthened microcrystalline glass according to any one of claims 14 to 17.

22. The electronic device according to claim 21.

23. The housing includes a rear cover attached to a rear surface of the electronic device, and the rear cover includes the microcrystalline glass according to any one of claims 1 to 13 or the chemically strengthened microcrystalline glass according to any one of claims 14 to 18.

23. The electronic device according to claim 21 or 22.

24. The electronic device further includes a camera element built into the housing, the housing includes a camera protective cover provided on the camera element, and the camera protective cover includes the microcrystalline glass according to any one of claims 1 to 13 or the chemically strengthened microcrystalline glass according to any one of claims 14 to 18.

24. The electronic device according to claim 21, wherein the electronic device is a semiconductor device.

25. The electronic device further includes an intermediate frame, and the intermediate frame includes the microcrystalline glass according to any one of claims 1 to 13 or the chemically strengthened microcrystalline glass according to any one of claims 14 to 18.

25. The electronic device according to claim 20, wherein the electronic device is a semiconductor device.

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