Lithium-aluminum-silicon microcrystalline glass as well as preparation method and application thereof

Abstract

The invention relates to the technical field of glass ceramics, and discloses lithium-aluminum-silicon series glass ceramics as well as a preparation method and application thereof. The crystalline phase of the lithium-aluminum-silicon microcrystalline glass is one or more of beta-eucryptite, beta-spodumene, lithium silicate, zirconium dioxide and a beta-quartz solid solution; when the crystal phase is beta-eucryptite, lithium monosilicate and beta-spodumene, the mass sum of the beta-eucryptite, the lithium monosilicate and the beta-spodumene accounts for more than 80% of the total mass of the crystal phase; the lithium-aluminum-silicon series microcrystalline glass comprises the following components in percentage by mole: 45%-62% of SiO2, 8%-20% of Al2O3, 0%-30% of Li2O, 0.2%-1.5% of TiO2, 0.5%-3% of ZrO2, 0%-3% of B2O3, 0.5%-5% of Na2O, 0%-2% of K2O, 0%-3% of P2O5 and 0.2%-1% of a clarifying agent. Through the design of the components of the microcrystalline glass, the crystalline phase is mainly composed of crystals such as beta-eucryptite and beta-quartz solid solution, the coefficient of thermal expansion is effectively reduced, and the microcrystalline glass is more suitable for a complex temperature environment than common glass.

Description

Technical Field

[0001] This invention relates to the field of glass-ceramic technology, and in particular to a lithium aluminum silicon-based glass-ceramic, its preparation method, and its applications. Background Technology

[0002] Microcrystalline glass materials are functional materials obtained by effectively controlling the nucleation and crystallization processes of a basic glass with a defined composition, combined with processes such as light irradiation, heat treatment, or chemical strengthening, so that the interwoven crystal structures are uniformly distributed inside the glass body, ultimately resulting in a large number of glass phases and microcrystalline phases coexisting inside.

[0003] The micron-sized grains within glass-ceramics can blunt and bend crack tips, significantly improving their crack resistance and scratch resistance by preventing cracks from penetrating the crystals. However, if current glass-ceramics are directly used as mobile phone cover plates, their low bending strength and surface hardness mean their drop and impact resistance cannot meet the performance requirements of cover plates. Therefore, chemical strengthening processes are needed to further improve their mechanical properties. Most mobile terminal cover plates on the market use lithium aluminum silicon or high-aluminum glass-ceramics. Although these glasses undergo primary or secondary strengthening processes, achieving a stress layer depth (DOL) of 65-80 μm and a surface compressive stress (CS) of 600-700 MPa, when used as mobile terminal cover plates, especially when the stress layer exceeds the DOL, the chemically strengthened compressive stress layer cannot effectively seal internal cracks. Furthermore, the inaccurate control of most crystals within the glass-ceramic can easily lead to increased glass haze and a significant decrease in light transmittance, resulting in devitrification, which significantly limits its application as a cover plate material.

[0004] Therefore, existing technologies still need further improvement and development. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a lithium aluminum silicon-based microcrystalline glass, its preparation method, and its applications. It aims to solve the problem that existing lithium aluminum silicon-based microcrystalline glasses cannot simultaneously achieve both mechanical properties and transmittance.

[0006] The above-mentioned objective of the present invention is achieved through the following technical solution: a lithium aluminum silicon-based microcrystalline glass, wherein the crystal phase of the lithium aluminum silicon-based microcrystalline glass is one or more selected from β-nepheline, β-spodumene, lithium monosilicate, zirconium dioxide, and β-quartz solid solution; when the crystal phase is β-nepheline, lithium monosilicate, and β-spodumene, the sum of the masses of β-nepheline, lithium monosilicate, and β-spodumene accounts for more than 80% of the total crystal phase mass; The lithium aluminum silicon-based microcrystalline glass comprises, by molar percentage: 45-62% SiO2, 8-20% Al2O3, 0-30% Li2O, 0.2-1.5% TiO2, 0.5-3% ZrO2, 0-3% B2O3, 0.5-5% Na2O, 0-2% K2O, 0-3% P2O5, and 0.2-1% clarifying agent.

[0007] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0008] As a preferred technical solution, the lithium aluminum silicon-based microcrystalline glass further comprises, by molar percentage: 0.5-2% MgO and 0.3-1.5% CaO, and the molar ratio of MgO to CaO is 1:1-3:1.

[0009] As a preferred technical solution, the lithium aluminum silicon microcrystalline glass has a total crystallinity of 20-60%, an average grain size of 10-50nm, and the grain size M satisfies the following: the proportion of grains with 20nm≤M<60nm is 50%~90%, and the proportion of grains with 50nm≤M<100nm is ≤10%.

[0010] As a preferred technical solution, the lithium aluminum silicon-based microcrystalline glass has undergone two chemical strengthening treatments on its surface; the two chemical strengthening treatments include: treatment in molten salt containing NaNO3 at 420-480℃ for 4-20 hours; and treatment in molten salt containing KNO3 at 380-400℃ for 0.5-2 hours.

[0011] As a preferred technical solution, the lithium aluminum silicon microcrystalline glass, wherein the lithium aluminum silicon microcrystalline glass with a thickness of 0.7 mm has a DOL-0 greater than 110 μm, CS greater than 350 MPa, and CS_50 greater than 120 MPa.

[0012] As a preferred technical solution, the lithium aluminum silicon microcrystalline glass, wherein the lithium aluminum silicon microcrystalline glass with a thickness of 0.7 mm has an average transmittance ≥86% in the 400-800nm ​​wavelength band; haze ≤0.3%; and |b| ≤1.6.

[0013] As a preferred technical solution, the lithium aluminum silicon-based microcrystalline glass has a Vickers hardness ≥ 750 HV. 0.5 The ball impact resistance is ≥0.5J, and the bending strength is ≥350MPa.

[0014] Secondly, a method for preparing the above-mentioned lithium aluminum silicon microcrystalline glass, comprising: Weigh the oxides constituting the lithium aluminum silicon microcrystalline glass according to the formula ratio, mix them and melt them to obtain a molten liquid; The molten liquid is subjected to molding and annealing processes in sequence to obtain a glass precursor; The glass precursor is heat-treated to obtain the lithium aluminum silicon microcrystalline glass; The forming method is selected from any one of the following: flow drawing, floatation, casting, or roll forming.

[0015] As a preferred technical solution, the method for preparing lithium aluminum silicon microcrystalline glass includes the following heat treatment: nucleation treatment by holding at 590-680℃ for 2-6 hours; and crystallization treatment by heating to 700-780℃ at 1-5℃ / min and holding for 0.25-3 hours.

[0016] Thirdly, a lithium aluminum silicon microcrystalline glass as described above, or a lithium aluminum silicon microcrystalline glass prepared by the preparation method described above, is used as a material for preparing a cover plate for a display device.

[0017] Beneficial Effects: Compared to existing microcrystalline glass, which has limitations in terms of thermal expansion coefficient and mechanical properties, this invention designs the composition of the microcrystalline glass to primarily consist of crystals such as β-nepheline and β-quartz solid solution, effectively reducing the thermal expansion coefficient and making it more adaptable to complex temperature environments than ordinary glass. Furthermore, the chemical strengthening process in this invention significantly improves the surface hardness, scratch resistance, and impact resistance of the microcrystalline glass, making it superior to ordinary microcrystalline glass. Attached Figure Description

[0018] Figure 1 LAS phase diagram Detailed Implementation This invention provides a lithium aluminum silicon-based microcrystalline glass, its preparation method, and its applications. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0019] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. Simultaneously, the steps or actions in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed. The component designations used herein, such as "first," "second," etc., are merely for distinguishing the described objects and do not have any sequential or technical meaning.

[0020] Unless specifically indicated in the specific circumstances, the numerical ranges described in the embodiments of this application are intended to include the endpoints of the numerical ranges as well as all integers and fractions within the range. When a content, solubility, or other parameter is described in the form of a preferred range or preferred value, it should be understood that this is equivalent to disclosing any range by combining any preferred range with a preferred range, a preferred value with a preferred value, or a preferred range with a preferred value, without regard to whether such pairwise combinations are specifically interpreted in the embodiments. Unless otherwise specified in the specific circumstances, the component contents described in the embodiments of this application are expressed as mole percentages. In related technologies, glass-ceramics need to undergo chemical strengthening treatment to improve their strength. However, current glass-ceramics all suffer from changes in glass structure after crystallization, resulting in poor chemical stability of the glass phase, which makes them unable to pass environmental reliability tests such as the double 85 test. In order to at least partially solve one of the problems in the related technologies, one embodiment of this application provides a plain glass, also known as substrate glass or matrix glass, which refers to glass that has not undergone nucleation, crystallization, and strengthening treatment. Its composition, in molar percentage, includes: SiO2 45-62%, Al2O3 8-20%, Li2O 20-30%, TiO2 0.2-1.5%, ZrO2 0.5-3%, B2O3 0-3%, Na2O 0.5-5%, K2O 0-2%, P2O5 0-3%, and 0.2-1% clarifying agent. Firstly, SiO2 is the basic component of the glass composition provided in this application. It forms the network structure of glass and glass-ceramics, and after crystallization, it forms β-nepheline (LiAlSiO4), β-spodumene (LiAlSi2O6), etc. It should be noted that if the SiO2 content is below 45%, fewer crystals will form in the glass-ceramics, and the crystals will tend to coarsen, affecting the properties of the glass-ceramics and glass-ceramic products, such as haze and drop ball test height. Therefore, the lower limit of the SiO2 content is preferably 45%. Furthermore, if the SiO2 content is above 62%, the glass melting temperature is high, making it difficult to melt and form, thus affecting the consistency of the glass. Therefore, the upper limit of the SiO2 content is preferably 62%. In some embodiments, the glass composition may contain about 62%, 61%, 60%, 59%, 58%, 57%, 56%, 55%, 54%, 53%, 52%, 51%, 50%, 49%, 48%, 47%, 46%, or 45% SiO2. Preferably, the SiO2 content is 45% to 62%.

[0021] Al₂O₃ is an intermediate oxide in glass formation and is also one of the crystal participating elements in β-nepheline (LiAlSiO₄) and β-spodumene (LiAlSi₂O₆). It can significantly improve the thermal stability of both base glass and glass-ceramics. Furthermore, because [AlO₄] has a larger volume than [SiO₄], it provides more space for ion exchange; therefore, alumina can promote ion exchange. In this invention, the Al₂O₃ content is 8–20%, and can be any value within the range of 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or any two of the above values.

[0022] Li₂O is a highly reactive alkali metal oxide and an oxide of the glass network. As an additive to reduce the high-temperature viscosity of the base glass, it can significantly improve the high-temperature fluidity of the base glass. At the same time, Li⁺ can participate in the ion exchange chemical strengthening reaction in the microcrystalline glass provided by this invention, further enhancing the mechanical properties of the microcrystalline glass. In this invention, Li₂O is 20-30%, and can be any value within the range of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or any two of the above values.

[0023] TiO2 is one of the nucleating agents for crystal nucleation and growth in glass ceramics. It can effectively promote the growth of crystal nuclei in the base glass during the nucleation and crystallization process, while improving the stability of the glass. The introduction of TiO2 effectively promotes the precipitation of crystal nuclei during the nucleation process. At the same time, the introduction of TiO2 can easily cause phase separation in the base glass, leading to crystallization and affecting the formation of the glass. In this invention, the content of TiO2 ranges from 0.2% to 1.5%, specifically 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, and any value within any range of any two of the above values.

[0024] ZrO2 is an intermediate oxide in glass formation, which can improve the chemical stability, hardness, scratch resistance, and drop resistance of glass. Furthermore, due to its high cation charge and strong field, ZrO2 has a significant accumulation effect on the glass structure and is commonly used as a nucleating agent in glass ceramics. However, excessive ZrO2 will greatly increase the viscosity of the glass, affecting its formability. In the embodiments of this invention, the molar percentage of ZrO2 ranges from 0.5% to 3%, specifically 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, and any value within any range of any two of the above values.

[0025] B₂O₃, as an outer oxide of the glass network, generally fills the voids in the silicon-oxygen tetrahedral framework. Its cation coordination remains largely unchanged, and some properties of its oxide can be considered constant. B₂O₃ helps to provide a base glass with a low melting temperature. Furthermore, adding B₂O₃ to the base glass can improve the damage resistance of the glass-ceramic and reduce the coefficient of thermal expansion; however, excessive B₂O₃ can compromise the stability of the base glass. In this invention, the B₂O₃ content is 0–3%, specifically 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, and any value within any range of any two of the above values. Na₂O is an important element involved in the ion exchange chemical strengthening of glass-ceramics to obtain strengthened glass-ceramics. It can also act as a flux during the high-temperature melting of the base glass, significantly reducing its melting temperature. However, excessively high Na₂O content leads to a significant decrease in the chemical stability of the glass-ceramics. Therefore, the Na₂O content in the glass-ceramics of this invention can be 0.5% to 5%, specifically 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, and 1.6%. 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5%, and any value within the range formed by any two of the above values.

[0026] K2O can reduce the high-temperature viscosity of the base glass, significantly improving its formability and fluidity at high temperatures, while also significantly reducing the cracking rate. In particular, adding a small amount of K2O can slow down the crystallization behavior that occurs during the molding of glass-ceramics. The K2O content in this invention can be 0-2%, specifically 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any value within the range of any two of the above values.

[0027] P2O5 can be used as a nucleating agent in base glass and glass-ceramics, promoting phase separation and overall crystallization of the base glass. If the P2O5 concentration is too low, the base glass will not easily crystallize, and crystals will only form from the surface inward at higher temperatures and lower viscosity. If the P2O5 concentration is too high, devitrification will be difficult to control during cooling in the base glass formation process. In the embodiments of the present invention, the P2O5 content ranges from 0 to 3%, specifically 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, and any value within the range of any two of the above values.

[0028] The basic glass composition involved in this invention also includes a clarifying agent at a mass ratio of 0.2% to 1%, which can effectively homogenize and clarify the basic glass composition and eliminate air bubbles inside the glass. The clarifying agent is selected from one or more of NaCl, Sb2O3, As2O3, nitrates, and sulfates. The content of the clarifying agent can be any value within the range of 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any two of the above values.

[0029] Secondly, the present invention provides a method for preparing microcrystalline glass, comprising the following steps: S100, Mix the compounds corresponding to the percentage of the microcrystalline glass oxide components evenly, in Melted at 1500-1580℃ for 4-6 hours, then clarified and homogenized at 1350-1450℃, and then cast into shape. The base glass is obtained after thorough annealing; the forming method is any one of casting, rolling, float glass, or overflow glass. one way; S200: The base glass obtained in S100 is subjected to nucleation crystallization heat treatment, wherein the nucleation temperature is... The nucleation temperature is 650-680℃, and the nucleation time is 120-360 min; the crystallization temperature is 720-750℃, and the crystallization time is 60 min, to obtain the microcrystalline glass. There are no particular limitations on the preparation method of the transparent microcrystalline glass of the present invention, as long as the purpose of the present invention can be achieved.

[0030] Furthermore, the two chemical strengthening steps include: The glass-ceramic sheet is immersed in a mixed molten salt of NaNO3 and / or KNO3 in a molten state at 420-480℃ for 4-20 hours to obtain a first chemically strengthened glass-ceramic; then the first chemically strengthened glass-ceramic is immersed in a molten salt of KNO3 in a molten state at 380-400℃ for 0.5-2 hours for a second chemical strengthening to obtain the strengthened glass-ceramic.

[0031] This invention provides a reinforced glass ceramic, which is prepared by the aforementioned method for preparing reinforced glass ceramics.

[0032] In some embodiments, the surface stress layer depth DOL of the reinforced glass ceramic is greater than 110 μm; the surface compressive stress CS of the transparent glass ceramic is greater than 350 MPa, and the CS_50 value is greater than 120 MPa.

[0033] In some embodiments, the Vickers hardness of the reinforced glass-ceramic is greater than or equal to 750 HV.0.5 The flexural strength M is greater than or equal to 350 MPa.

[0034] In some embodiments, the reinforced glass ceramic, with a thickness of 0.7 mm, has an average transmittance of greater than or equal to 86% across the entire wavelength range of 400 nm to 800 nm, a haze of less than or equal to 0.3%, and a B value range of |b|≤1.6 in the Lab color model.

[0035] In some embodiments, the reinforced glass ceramic, with a thickness of 0.70 mm, can withstand an impact energy of ≥0.50 Joules under directional impact from a 32g steel ball.

[0036] For the lithium-aluminum-silicon chemically strengthened glass-ceramics of the present invention: a compressive stress layer of a certain depth is formed on the surface of the glass-ceramics through ion exchange, while a tensile stress layer capable of achieving force balance with the compressive stress layer is formed inside the glass-ceramics. It should be understood that after the chemical strengthening ion exchange process, the composition of the stress layer formed in the glass-ceramics may be slightly different from that of the un-ion-exchanged glass-ceramics. This is because during ion exchange, the small-radius alkali metal ions (e.g., Li₂) contained inside the un-ion-exchanged glass-ceramics... + Or Na + ) will be affected by large-radius alkali metal ions (such as Na) in the molten salt of the salt bath. + or K + Replaced by, for example, Li in microcrystalline glass. + Na in molten salt of salt bath + To exchange, by Na + The Na that is replaced, and / or, in the glass + K in molten salt for strengthening salt bath + To exchange, K + Instead, it is replaced. However, in the embodiments, the composition of the glass-ceramic at or near the center of the depth of the glass article will still have the composition of the newly formed glass-ceramic. That is, the composition of the tensile stress layer in the lithium aluminum silicon chemically strengthened glass-ceramic that has not undergone ion exchange will still have the composition of the glass-ceramic.

[0037] The chemically strengthened transparent microcrystalline glass described in the third aspect of the present invention can be used as a protective cover glass material for displays of consumer electronic devices and automotive display devices, wherein the electronic devices include at least one of mobile phones, tablet computers, smart wearables, displays, and televisions. The electronic devices or automotive display devices may include a housing and electronic components partially located within the housing. The housing includes a front surface, a rear surface, and a side surface. The electronic components include a display device located on or adjacent to the front surface of the housing.

[0038] The lithium aluminum silicon chemically strengthened microcrystalline glass provided by the present invention can be applied to the front surface and / or rear surface and / or side surface of the housing; preferably, the electronic device or vehicle display device may further include a cover article covering the front surface of the housing or located on the display device, and the lithium aluminum silicon chemically strengthened microcrystalline glass provided by the present invention can be applied to the cover article.

[0039] Terminology Explanation: Base glass: Glass that has been uniformly mixed with compounds containing the oxides, melted at high temperature and cast, rolled or drawn, and annealed without nucleation crystallization heat treatment or ion exchange strengthening treatment.

[0040] Glass-ceramics, also known as microcrystalline glass, are a type of solid composite material that contains both glass phase and crystalline phase (microcrystalline phase, crystalline phase) by subjecting a base glass to controlled crystallization heat treatment with a set target.

[0041] Nucleation: The process of heat treatment to grow tiny crystal nuclei from nucleating material in a base glass.

[0042] Crystallization: The process of growing a certain type of crystal on the basis of a crystal nucleus by heat treatment of a base glass.

[0043] Crystal phase: Crystal phase is the microscopic structure of crystals, and is a general term for the parts composed of a large number of crystalline solid phases.

[0044] DOL_0: Compressive stress layer depth, also known as compressive stress layer depth, refers to the distance from any surface of the glass-ceramic material to the point near which the compressive stress is zero. It is obtained by measuring with an SLP-2000 stress meter. The unit is μm.

[0045] Surface compressive stress (CS): After chemical strengthening of glass and ceramics, smaller alkali metal ions on the surface are replaced with larger alkali metal ions. Due to the crowding effect of the larger alkali metal ions, compressive stress is generated on the glass surface, which is called surface compressive stress. Surface CS is measured by an SLP-2000 stress meter, and the unit is MPa.

[0046] CS_50: Compressive stress at a depth of 50 μm from the glass surface, in MPa.

[0047] Transmittance (TR): The ratio of the radiant energy projected onto and transmitted through an object to the total radiant energy projected onto the object as the incident luminous flux travels from the incident surface of the irradiated surface to the other side.

[0048] Refractive index λ: The ratio of the speed of light in a vacuum to the speed of light in the medium.

[0049] In the embodiments and comparative examples of the present invention, the transmittance of the glass ceramic at wavelengths of 400-1000 nm or 550 nm is the average transmittance of multiple glass samples from the same batch measured at wavelengths of 400-1000 nm or 550 nm. At least 5 samples from each batch of glass ceramic are tested.

[0050] Instruments and testing methods Glass thickness: determined by micrometer measurement. The thickness change of the glass-ceramic material before and after chemical strengthening is very small. It can be ignored.

[0051] Crystal content testing: The glass-ceramic sample was tested using an X-ray diffractometer to obtain the XRD diffraction peak curve. The test result file (RAW format) from the X-ray diffractometer (Shimadzu XRD-6000) was then imported into X-ray diffraction data refinement software (such as Gsas, Fullprof, Maud) for fitting and calculation. The crystal content in the glass-ceramic sample can then be obtained. The ratio of the fitted crystal phase peak area to the total fitted peak area is the crystal content. The X-ray diffractometer used in this invention is a Shimadzu XRD. The diffraction angle range used in the test was 2θ = 10–80°, the scanning speed was 6° / min, the working voltage was 40KV, and the working current was 30mA. The average grain size was obtained by testing the glass-ceramic sample using an X-ray diffractometer. The average grain size was then calculated using the Scherrer formula D = Kλ / (βcosθ), where λ is the X-ray wavelength, β is the full width at half maximum (FWHM), and K = 0.89.

[0052] Transmittance test: The transmittance of the glass ceramic was tested using professional testing instruments according to the standard GB / T7962.12-2010 "Test Methods for Colorless Optical Glass Part 12: Internal Spectral Transmittance". The testing instruments used in this invention are the Konica Minolta CM-3600A spectrophotometer and the Shimadzu UV-2600 UV-Vis spectrophotometer.

[0053] Differential scanning calorimetry (DSC) test: The sample was ground into powder and passed through a 200-mesh sieve; the test conditions were: room temperature to 1000℃, heating rate of 10℃ / min; the test instrument was a Mettler Toledo TGA / DSC3+ thermogravimetric and simultaneous thermal analyzer.

[0054] The method for preparing the reinforced glass ceramic of the present invention includes the following steps: (1) Preparation of base glass: After uniformly mixing the above compounds containing various oxides, the mixture is melted at high temperature and annealed to obtain block or sheet base glass; (2) Preparation of glass ceramics: The base glass obtained in step (1) is subjected to nucleation crystallization heat treatment to obtain glass ceramics; (3) Cut, grind, polish or grind and polish the glass ceramic obtained in step (2) to obtain transparent glass ceramic sheets; (4) The transparent glass-ceramic sheet obtained in step (3) is subjected to ion exchange chemical strengthening treatment to obtain a strengthened glass-ceramic sheet.

[0055] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

[0056] Examples 1-4 Examples 1-4 all provide microcrystalline glass. The mass percentages of each component of the precursor glass are shown in Table 1. The precursor glass is heat-treated, specifically including the following steps: the precursor glass is heated to the nucleation and crystallization temperature at a heating rate of 3℃ / min, held at that temperature for 2-5 hours, and cooled to room temperature at a cooling rate not exceeding 2℃ / min. The heat-treated glass is cut, ground, and polished into glass sheets with dimensions of 45*40*0.65mm, placed in a bath containing 100% sodium nitrate, and treated at 420-480℃ for 4-20 hours to perform Na and Li exchange, and then treated in a mixed molten salt of 100% potassium nitrate at 380-400℃ for 0.5-2 hours to perform K and Na ion exchange. Chemically strengthened microcrystalline glass is obtained. After cooling, it is cleaned with an ultrasonic cleaner for 1 hour to remove residual molten salt from the glass surface, dried, and then tested. The preparation method process parameters are shown in Table 2, and the properties of the microcrystalline glass obtained in the examples are shown in Table 3.

[0057] Comparative Examples 1-2 The components of Comparative Examples 1-2 are shown in Table 1. The preparation methods are the same as those of Examples 1-4. The process parameters of the preparation methods are shown in Table 2. The properties of the microcrystalline glass obtained in the comparative examples are shown in Table 3.

[0058] Table 1. Formulation components of Examples 1-4 and Comparative Examples 1-2

[0059] Table 2. Heat treatment and chemical strengthening processes of Examples 1-4 and Comparative Examples 1-2

[0060] Table 3 Performance of Examples 1-4 and Comparative Examples 1-2

Claims

1. A lithium aluminum silicon-based microcrystalline glass, characterized in that, The crystalline phase of the lithium aluminum silicon-based microcrystalline glass is one or more of β-nepheline, β-spodumene, lithium monosilicate, zirconium dioxide, and β-quartz solid solution; when the crystalline phase is β-nepheline, lithium monosilicate, and β-spodumene, the sum of the masses of β-nepheline, lithium monosilicate, and β-spodumene accounts for more than 80% of the total crystalline phase mass. The lithium aluminum silicon-based microcrystalline glass comprises, by molar percentage: 45-62% SiO2, 8-20% Al2O3, 0-30% Li2O, 0.2-1.5% TiO2, 0.5-3% ZrO2, 0-3% B2O3, 0.5-5% Na2O, 0-2% K2O, 0-3% P2O5, and 0.2-1% clarifying agent.

2. The lithium aluminum silicon-based microcrystalline glass according to claim 1, characterized in that, The lithium aluminum silicon-based glass-ceramic further comprises, by molar percentage: 0.5-2% MgO and 0.3-1.5% CaO, wherein the molar ratio of MgO to CaO is 1:1-3:

1.

3. The lithium aluminum silicon-based microcrystalline glass according to claim 1, characterized in that, The total crystallinity of the lithium aluminum silicon microcrystalline glass is 20-60%, the average grain size is 10-50nm, and the grain size M satisfies the following conditions: the proportion of grains with a size of 20nm≤M<60nm is 50%~90%, and the proportion of grains with a size of 50nm≤M<100nm is ≤10%.

4. The lithium aluminum silicon-based microcrystalline glass according to claim 1, characterized in that, The surface of the lithium aluminum silicon microcrystalline glass has undergone two chemical strengthening treatments; the two chemical strengthening treatments include: treatment in molten salt containing NaNO3 at 420-480℃ for 4-20 hours; and treatment in molten salt containing KNO3 at 380-400℃ for 0.5-2 hours.

5. The lithium aluminum silicon-based microcrystalline glass according to claim 4, characterized in that, The lithium aluminum silicon microcrystalline glass with a thickness of 0.7 mm has a DOL_0 greater than 110 μm, CS greater than 350 MPa, and CS_50 greater than 120 MPa.

6. The lithium aluminum silicon-based microcrystalline glass according to claim 1, characterized in that, The lithium aluminum silicon-based microcrystalline glass with a thickness of 0.7 mm has an average transmittance of ≥86% in the 400-800 nm wavelength band, haze ≤0.3%, and |b| ≤1.

6.

7. The lithium aluminum silicon-based microcrystalline glass according to claim 1, characterized in that, The Vickers hardness of the lithium aluminum silicon-based microcrystalline glass is ≥750 HV. 0.5 The ball impact resistance is ≥0.5J, and the bending strength is ≥350MPa.

8. A method for preparing the lithium aluminum silicon-based microcrystalline glass according to claim 1, characterized in that, include: Weigh the oxides constituting the lithium aluminum silicon microcrystalline glass according to the formula ratio, mix them and melt them to obtain a molten liquid; The molten liquid is subjected to molding and annealing processes in sequence to obtain a glass precursor; The glass precursor is heat-treated to obtain the lithium aluminum silicon microcrystalline glass; The forming method is selected from any one of the following: flow drawing, floatation, casting, or roll forming.

9. The method for preparing lithium aluminum silicon microcrystalline glass according to claim 8, characterized in that, The heat treatment includes: nucleation treatment by holding at 590-680℃ for 2-6 hours; and crystallization treatment by heating to 700-780℃ at 1-5℃ / min and holding for 0.25-3 hours.

10. A lithium aluminum silicon microcrystalline glass according to any one of claims 1-7 or a lithium aluminum silicon microcrystalline glass prepared by any one of claims 8-9, used as a material for preparing a cover plate for a display device.

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