A transparent glass-ceramics and its preparation method

Abstract

The present invention discloses a transparent glass-ceramics, whose crystalline phases include a main crystalline phase and a secondary crystalline phase. The mass ratio of the main crystalline phase accounts for 70-98% of all crystalline phases. The main crystalline phase is a calcium fluoride crystalline phase, and the mass of the calcium fluoride crystalline phase accounts for 34-60% of the transparent glass-ceramics. The secondary crystalline phase includes a lithium silicate crystalline phase and / or a lithium disilicate crystalline phase. The mass ratio of the lithium silicate crystalline phase in the transparent glass-ceramics is less than 15%, and the mass ratio of the lithium disilicate crystalline phase in the transparent glass-ceramics is less than 15%. The present invention also provides a preparation method of the above-mentioned transparent glass-ceramics. The transparent glass-ceramics of the present invention, through the optimization of the crystalline phase structure, obtain a crystal structure with a high calcium fluoride crystalline phase and a low lithium silicate crystalline phase and / or a lithium disilicate crystalline phase, so that the glass-ceramics of the present invention have excellent mechanical properties and transparency.

Description

Technical Field

[0001] The present invention belongs to the field of glass, and particularly relates to a glass-ceramics and a preparation method thereof. Background Art

[0002] With the rise of 5G technology, wireless charging technology and electronic products, transparent and excellent-performance glass materials are widely used in various devices. For example, the glass used in devices such as LED displays must have sufficient strength and chemical stability to withstand conventional contact without damage. Moreover, glass is also widely used in portable electronic products. Such electronic devices not only put forward higher requirements for optical properties (including light transmittance, haze and refractive index, etc.), but also need to be able to withstand bending, scratching and impact. At present, most glass materials use high-aluminum silicon glass. Although its mechanical properties have been improved through process treatment, it still cannot meet the requirements.

[0003] Glass-ceramics is a material in which crystals precipitate inside by heat-treating glass. Its mechanical properties are superior to those of conventional glass, and it has significant advantages in bending resistance, wear resistance and drop resistance. Glass-ceramics can also further improve the mechanical properties through chemical strengthening. Based on these advantages, glass-ceramics and its products are widely used in display devices and electronic devices with higher requirements for drop resistance, compression resistance and scratch resistance, especially on the front and back covers of portable electronic devices (such as mobile phones, watches, tablet computers, etc.). However, the glass-ceramics currently on the market has problems of poor chemical strengthening performance and low light transmittance, and it is difficult to meet the requirements of high-demand display devices or electronic devices.

[0004] Therefore, developing transparent glass-ceramics and its products with excellent mechanical properties and high light transmittance has become the research goal. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned deficiencies and defects in the background art, and provide a transparent glass-ceramics with excellent mechanical properties and high light transmittance and a preparation method thereof.

[0006] To solve the above technical problem, the technical solution proposed by the present invention is as follows:

[0007] A transparent glass-ceramics, its crystal phase includes a main crystal phase and a secondary crystal phase. The mass ratio of the main crystal phase accounts for 70-98% of all crystal phases. The main crystal phase is a calcium fluoride crystal phase, and the mass of the calcium fluoride crystal phase accounts for 34-60% of the transparent glass-ceramics. The secondary crystal phase includes a lithium silicate crystal phase / and or a lithium disilicate crystal phase. The mass ratio of the lithium silicate crystal phase in the transparent glass-ceramics is less than 15%, and the mass ratio of the lithium disilicate crystal phase in the transparent glass-ceramics is less than 15%.

[0008] In the above-mentioned transparent glass-ceramics, preferably, the mass ratio of the main crystal phase accounts for 77-90% of all crystal phases, the mass ratio of the calcium fluoride crystal phase accounts for 43-60% of the transparent glass-ceramics, the secondary crystal phase includes lithium silicate crystal phase and / or lithium disilicate crystal phase, the mass ratio of the lithium silicate crystal phase accounts for 2-12% of the transparent glass-ceramics, and the mass ratio of the lithium disilicate crystal phase accounts for 1-10% of the transparent glass-ceramics.

[0009] In the above-mentioned transparent glass-ceramics, preferably, the grain sizes of the main crystal phase and the secondary crystal phase are below 50 nm, and more preferably, the grain sizes of the main crystal phase and the secondary crystal phase are below 35 nm. A large grain size in the glass-ceramics easily leads to a decrease in the light transmittance of the glass-ceramics and even devitrification, which will limit the application of the glass-ceramics. Therefore, in order to obtain a glass-ceramics with high transparency, it is necessary to ensure that the crystal size is much smaller than the visible light wavelength. In the present invention, by controlling the grain sizes of the main crystal phase and the secondary crystal phase to be below 50 nm, and more preferably below 35 nm, a glass-ceramics with high light transmittance can be obtained.

[0010] In the present invention, the crystal phase satisfies the characteristic of "high calcium fluoride crystal phase, low lithium silicate crystal phase and / or lithium disilicate crystal phase". The polycalcium fluoride crystal reduces the nucleation and crystallization energy of crystal precipitation, is conducive to the precipitation and formation of crystals, and can effectively reduce the heat treatment temperature. The addition of the secondary crystal phase can effectively increase the number of crystal nuclei in the glass-ceramics and reduce the crystal size. The arrangement of the glassy state is disordered, the structure is relatively loose, and the binding ability is poor. The formation of crystals transforms some glass phases into crystal phases with higher strength. At the same time, the main and secondary crystals are arranged orderly, the structure is more dense, and the performance is enhanced. Through the synergistic effect of the main crystal phase and the secondary crystal phase, the present invention is conducive to improving the light transmittance and mechanical properties.

[0011] In the above-mentioned transparent glass-ceramics, preferably, calculated by mass fraction, its components include: SiO2: 30-50%; Al2O3: 15-30%; Li2O: 1-5%; Na2O: 2-6%; CaF2: 5-20%; ZrO2: 1-2%; rare earth metal oxides: not exceeding 1%; B2O3: 0-3%; ZnO: 0-2%; MgO: 0-2%; P2O5: 0-7%; fining agent: 0-1%; the fining agent is one or more of Sb2O3, SnO2 and CeO2; the rare earth metal oxides are one or more of Y2O3, Yb2O3 and La2O3.

[0012] In the above-mentioned transparent glass-ceramics, more preferably, by mass fraction, the components include: SiO2: 35-45%; Al2O3: 20-25%; Li2O: 2-5%; Na2O: 2.5-4%; CaF2: 9-16%; ZrO2: 1.5-2%; lanthanide metal oxides: 0.5-0.8%; B2O3: 0-2%; ZnO: 0-1.5%; MgO: 0-1.5%; P2O5: 1-7%; fining agent: 0-0.5%; the fining agent is one or more of Sb2O3, SnO2 and CeO2; the lanthanide metal oxides are one or more of Y2O3, Yb2O3 and La2O3.

[0013] In the above-mentioned transparent glass-ceramics, preferably, the mass ratio of CaF2 to lanthanide metal oxides is (20-140):1, the mass ratio of ZrO2 to lanthanide metal oxides is (1.5-15):1, the mass ratio of CaF2 to ZrO2 is (7-12):1, and the mass ratio of the total mass of Li2O+Na2O to CaF2 is (0.3-0.6):1.

[0014] In the above-mentioned transparent glass-ceramics, more preferably, the mass ratio of CaF2 to lanthanide metal oxides is (20-32):1, and the mass ratio of ZrO2 to lanthanide metal oxides is (1.8-4):1.

[0015] In the present invention, simply increasing the CaF2 in the raw materials cannot meet the requirements of the crystal phase (crystal structures of high calcium fluoride crystal phase, low lithium silicate crystal phase / and or lithium disilicate crystal phase) and size (below 50 nm) of the present invention. It is necessary to carry out collaborative design on the dosages of other elements in the glass. Our research shows that suitable CaF2 / lanthanide metal oxides can control the amount of lanthanide metal oxides entering the precipitated calcium fluoride crystals. The sizes of these lanthanide metal-calcium fluoride crystals are smaller, reducing the grain size and promoting the formation of nanoscale glass-ceramics; suitable ZrO2 / lanthanide metal oxides can make the transparent glass-ceramics have high transparency. There are vacancy defects in the lanthanide metal oxides. When the lanthanide metal oxides are added to the glass composition, ZrO2 can enter the vacancy defects of the crystals, making the atomic arrangement in the glass structure more compact and the transparency of the crystals higher; both CaF2 / ZrO2 are nucleating agents. Appropriate addition of nucleating agents and formation of corresponding crystals. Suitable CaF2 / ZrO2 can provide crystallization sites for the nucleation of crystals; the addition of lithium and sodium oxides can enter the glass network to form crystals. Suitable (Li2O + Na2O) / CaF2 can obtain ideal crystals after crystallization, making the glass-ceramics exhibit transparency. Generally speaking, through the mass ratios of CaF2 and lanthanide metal oxides, ZrO2 and lanthanide metal oxides, CaF2 and ZrO2, and the total mass of Li2O + Na2O and CaF2, the present invention can obtain crystals with specific grain sizes and specific main and secondary crystals. The product transparent glass-ceramics have high light transmittance and good mechanical properties.

[0016] In the above-mentioned transparent glass-ceramics, preferably, the mass ratio of SiO2 and Al2O3 is (1.5 - 2):1, the total mass ratio of SiO2 + Al2O3 and Li2O is (13 - 20):1, and the mass ratio of Li2O and Na2O is (1 - 1.4):1. Suitable SiO2 / Al2O3 can make the raw materials have a suitable melting temperature to make the glass clarified and homogenized; suitable (SiO2 + Al2O3) / Li2O can make the glass have a suitable melting temperature and viscosity, promote the clarification of the base glass, and reduce the bubbles in the base glass; suitable Li2O / Na2O can make the glass have appropriate crystallization ability and viscosity. Through the above limitations, the present invention can change the properties of the glass melt, and in cooperation with the aforementioned limitations on CaF2, ZrO2 and lanthanide metal oxides, etc., it is possible to prepare a crystal structure of high calcium fluoride crystal phase, low lithium silicate crystal phase / and or lithium disilicate crystal phase. The cooperation of multiple crystal phases with specific ratios can obtain transparent glass-ceramics with high light transmittance and excellent mechanical properties.

[0017] As a general technical concept, the present invention also provides a method for preparing the above-mentioned transparent glass-ceramics, comprising the following steps: preparing a base glass plate, and then subjecting the base glass plate to crystallization treatment by a two-step heat treatment method, thereby obtaining the transparent glass-ceramics; the two-step heat treatment is to perform nucleation treatment at a first temperature and perform crystal growth treatment at a second temperature higher than the first temperature.

[0018] In the above preparation method, preferably, the first temperature is 500-700 °C, the second temperature is 650-850 °C, the holding time at the first temperature is 1-10 h, and the holding time at the second temperature is 0.5-5 h.

[0019] The functions of each component are described below:

[0020] SiO2: SiO2 is an important glass-forming oxide, which forms an irregular continuous network with the structural unit of silicon-oxygen tetrahedron [SiO4] to become the skeleton of the glass. SiO2 can reduce the thermal expansion coefficient of the glass, and can improve the thermal stability, chemical stability, heat resistance, hardness, mechanical strength, viscosity and ultraviolet transmittance of the glass. However, when the content is high, a higher melting temperature is required, and it may cause crystallization.

[0021] Al2O3: Al2O3 is one of the essential components of the base glass and belongs to intermediate oxides. There are tetracoordinated [AlO4] and octacoordinated [AlO6] in the glass. In Al2O3, Al 3+ with a higher coordination number (6) makes oxygen tend to be closely arranged, which is beneficial to adjusting into regularly arranged crystals. Al2O3 can reduce the crystallization tendency of the glass, improve the chemical stability, thermal stability, mechanical strength, hardness and refractive index of the glass, can reduce the erosion of refractory materials, and helps with the opacification of fluorides. Al2O3 can control or inhibit the phase separation and crystallization of the glass. It belongs to refractory oxides and can increase the viscosity of the glass, making it more difficult for the glass to be clarified and homogenized. Therefore, the content of Al2O3 in the base glass should not exceed 30 wt%.

[0022] Li2O: Li2O is a network modifier oxide, which can significantly reduce the melting temperature and viscosity of the glass, promote the clarification of the base glass, and at the same time reduce the thermal expansion coefficient and crystallization temperature of the glass, and the crystallization tendency becomes smaller. A large amount of Li2O increases the crystallization tendency again. In general glass, the content of Li2O should not exceed 5 wt%.

[0023] Na2O: Na2O is a glass network modifier oxide, sodium ion (Na +)Reside in the cavities of the glass structure network. Na2O can increase the free oxygen, increasing the O / Si ratio in the glass structure and causing bond breakage. Therefore, it can reduce the viscosity of the glass, making the glass easier to melt and being a good flux for the glass. Na2O increases the thermal expansion coefficient of the glass, reducing its thermal stability, chemical stability, and mechanical strength. When using Na2O in the composition of the glass-ceramics, it can reduce the crystallization activation energy and the glass crystallization temperature of the glass, making the glass crystallization ability weaker and resulting in an increase in the residual glass phase. Therefore, the amount of Na2O introduced should not be excessive, generally not exceeding 5wt%.

[0024] CaF2: CaF2 is a very good nucleating agent. It exists in an ionic state in the high-temperature melt and has great fluidity. During the cooling process of the melt, fluoride ions precipitate, providing good crystallization sites for the nucleation of crystals. During the precipitation process of fluoride nanocrystals, the changes in the surrounding components and structure enable the crystals to be evenly distributed in the glass matrix, thus avoiding agglomeration. However, if the content of CaF2 is too high, it will cause the glass-ceramics to become turbid. Therefore, the content of CaF2 should not be too high, generally not exceeding 20%.

[0025] ZrO2: ZrO2 is an intermediate oxide that can increase the viscosity, hardness, elasticity, refractive index, and chemical stability of the glass, and reduce the thermal expansion coefficient of the glass. Glass containing ZrO2 is relatively difficult to melt, and it is prone to crystallization when the content exceeds 3%. ZrO2 is used to manufacture glass with good chemical stability and thermal stability, especially alkali-resistant glass, as well as optical glass with a high refractive index; ZrO2 is also used as a nucleating agent for glass-ceramics and a raw material for high-quality refractory materials.

[0026] B2O3: B2O3 is an optional component that helps improve the low-temperature meltability of the glass. In small amounts, it acts as a flux and enhances chemical stability, etc. However, if the content is too high, it will make clarification difficult, resulting in devitrification of the glass. Therefore, the content of B2O3 does not exceed 3wt%.

[0027] ZnO: ZnO is an intermediate oxide and an optional component. Generally, zinc oxide octahedra are used as network external oxides. When there is enough free oxygen in the glass, zinc oxide tetrahedra can be formed and enter the glass structure network, making the glass structure more stable. It can reduce the thermal expansion coefficient of the glass and improve the chemical stability, thermal stability, and refractive index of the glass. However, if the dosage is too high, the glass is prone to crystallization. Therefore, the content of ZnO does not exceed 2wt%.

[0028] MgO: MgO is an external network oxide and an optional component. It can slow down the hardening rate of the glass, improve the forming performance of the glass. MgO can also reduce the crystallization tendency and crystallization rate, increase the high-temperature viscosity of the glass, and improve the chemical stability and mechanical strength of the glass. However, if the content of MgO is too high, it may cause a decrease in devitrification resistance. After crystallization, an unsatisfactory crystal will be obtained, resulting in a decline in the performance of the transparent microcrystalline glass. Therefore, the content of MgO does not exceed 2 wt%.

[0029] P2O5: P2O5 is an optional component that helps improve the low-temperature fusibility of the glass. It can phase-separate in the glass to form crystal nuclei and improve the thermal expansion stability of the glass during the crystallization process. However, if the content of P2O5 is too high, it is easy to reduce the phase separation of the glass and cause devitrification. Therefore, the content of P2O5 does not exceed 7 wt%.

[0030] Lanthanide metal oxides: Their addition can refine the grain size and improve the transmittance of the transparent microcrystalline glass, but their dosage needs to be reasonably controlled.

[0031] The transparent microcrystalline glass of the present invention, through the optimization of the crystal phase structure, obtains a crystal structure with a high calcium fluoride crystal phase, a low lithium silicate crystal phase / and or a lithium disilicate crystal phase. At the same time, in order to prepare the above crystal phase structure, the components of the transparent microcrystalline glass are also reasonably optimized and designed. Finally, the prepared transparent microcrystalline glass has good light transmittance and mechanical properties. After testing, the average light transmittance of the transparent microcrystalline glass product with a thickness of less than 1 mm at a wavelength of 400 - 800 nm is more than 85.0%, the light transmittance of the transparent microcrystalline glass product with a thickness of less than 1 mm at a wavelength of 550 nm is more than 90%, the surface pressure of the transparent microcrystalline glass product with a thickness of less than 1 mm is at least 300 MPa, and the Vickers hardness of the transparent microcrystalline glass product with a thickness of less than 1 mm is at least 600 kgf / mm 2 The drop resistance of the transparent microcrystalline glass product with a thickness of less than 1 mm is more than 1800 mm, the crystallinity is more than 35%, the grain size is small, and it is less than 50 nm.

[0032] Compared with the prior art, the advantages of the present invention are as follows:

[0033] The transparent microcrystalline glass of the present invention, through the optimization of the crystal phase structure, obtains a crystal structure with a high calcium fluoride crystal phase, a low lithium silicate crystal phase / and or a lithium disilicate crystal phase, making the microcrystalline glass of the present invention have excellent mechanical properties and transparency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a physical picture of the transparent glass-ceramics prepared in Example 1.

[0036] Figure 2 It is an XRD pattern of the transparent glass-ceramics prepared in Example 1.

[0037] Figure 3 It is the transmittance curve of the transparent glass-ceramics prepared in Example 1.

[0038] Figure 4 It is an SEM image of the transparent glass-ceramics prepared in Example 1.

[0039] Figure 5 It is the transmittance curve of the transparent glass-ceramics prepared in Comparative Example 2. Detailed implementation manners

[0040] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in combination with the accompanying drawings of the specification and the preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all the technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0042] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through the market or can be prepared by existing methods.

[0043] The glass-ceramics and glass-ceramic products of the present invention are a kind of polycrystalline solid materials containing a large number of crystalline phases and glass phases. The crystalline phases in the glass-ceramics are different from amorphous solids and can be distinguished by X-ray diffraction and scanning electron microscopy. For the glass-ceramics of the present invention, the crystalline phases include calcium fluoride crystals, lithium silicate, etc. The formation of multiple crystalline phases can improve the light transmittance and performance of the transparent glass-ceramics.

[0044] Through repeated experiments and research, the inventors of the present invention have specified the content and content ratio of specific components of the transparent glass-ceramics as specific values and precipitated the above-mentioned crystalline phases, so as to obtain the transparent glass-ceramics in the present invention with relatively low components.

[0045] Example 1:

[0046] This example is used to illustrate the preparation of the transparent glass-ceramics according to the formula and process parameters in Table 1 of the present invention, and the preparation method of the transparent glass-ceramics is as follows.

[0047] The method for preparing the transparent glass-ceramics includes the following steps: configuring raw materials according to the components and mass fractions shown in Table 1 to prepare the base glass; performing crystallization treatment on the base glass by a two-step heat treatment method to obtain the transparent glass-ceramics. The crystallization treatment includes the following steps: performing nucleation treatment at the first temperature and performing crystal growth treatment at the second temperature higher than the nucleation process temperature. Among them, the first temperature of the crystallization treatment is 600 °C, and the holding time at the first temperature is 4 h. The second temperature of the crystallization treatment is 700 °C, and the holding time at the second temperature is 0.5 h.

[0048] Examples 2-10:

[0049] Compared with Example 1, Examples 2-10 are different in the raw material components, specifically as shown in Table 1 and Table 2 below.

[0050] Comparative Examples 1-4:

[0051] Compared with Example 1, Comparative Examples 1-4 are different in the raw material components, specifically as shown in Table 3 below.

[0052] Table 1: Raw material components and process parameters in Examples 1-4

[0053]

[0054] Table 2: Raw material components and process parameters in Examples 5-10

[0055]

[0056] Table 3: Raw material components and process parameters in Comparative Examples 1-4

[0057]

[0058] The transparent glass-ceramics prepared in Examples 1-10 and Comparative Examples 1-4 are tested, and the following methods are used to test each performance index:

[0059] Refractive index: The refractive index (nd) is tested according to the method of GB / T7962.1-2010.

[0060] Grain size: The transparent glass-ceramics are surface-treated with HF acid, and then the grain size is measured by using a SEM scanning electron microscope.

[0061] Light transmittance: The transparent glass-ceramics were cut into a thickness of 1 mm, polished, and the average light transmittance in the range of 400 - 800 nm was measured using a spectrophotometer.

[0062] Vickers hardness: Measured using a Vickers hardness tester with a load of 200 g and a loading time of 15 s.

[0063] Drop ball height: The polished transparent glass-ceramics with dimensions of 150×60×0.6 mm (length×width×height) were placed on a rubber holder and fixed. The maximum drop ball height from which a 102 g steel ball can fall without causing the transparent glass-ceramics to break and being able to withstand the impact.

[0064] Surface stress: Measured using a surface stress meter for the surface stress of the transparent glass-ceramics.

[0065] Density: Measured according to Archimedes' principle in accordance with the method of GB / T 7962.20 - 2010.

[0066] The test results are shown in Tables 4, 5, 6 and Figures 1-5 as follows.

[0067] Table 4: Performance data in Examples 1 - 4

[0068]

[0069] Table 5: Performance data in Examples 5 - 10

[0070]

[0071] Table 6: Performance data in Comparative Examples 1 - 4

[0072]

[0073] It can be seen from the examples and comparative examples that when the raw material composition does not meet the limitations in the present invention, the main crystal phase is difficult to meet the high calcium fluoride crystal phase, low lithium silicate crystal phase / and or lithium disilicate crystal phase, resulting in a decrease in the visible light transmittance to about 80%. At the same time, when the crystal phase does not meet the high calcium fluoride crystal phase, low lithium silicate crystal phase / and or lithium disilicate crystal phase, the performance such as Vickers hardness, drop ball height, surface stress, density and crystallinity all decreases, thus affecting the application of the transparent glass-ceramics. When the raw material composition meets the limitations of the present invention, it promotes the formation of multiple crystal phases, the main crystal phase meets the high calcium fluoride crystal phase, low lithium silicate crystal phase / and or lithium disilicate crystal phase, which can improve the transmittance of the transparent glass-ceramics, refine the grain size, and the formation of multiple crystal phases can improve the performance of the transparent glass-ceramics.

[0074] Figure 1 Figure is the physical image of the transparent glass-ceramics prepared in Example 1. From Figure 1It can be seen that the glass-ceramics prepared in Example 1 exhibit transparency. Figure 2 XRD pattern of the transparent glass-ceramics prepared in Example 1. It can be seen from Figure 2 that the main crystal of the glass-ceramics prepared in Example 1 is calcium fluoride crystal, and the content of other crystal phases is relatively small. Figure 3 Transmittance curve of the transparent glass-ceramics prepared in Example 1. It can be seen from Figure 3 that the visible light transmittance of the glass-ceramics prepared in Example 1 is 90%. Figure 4 SEM image of the transparent glass-ceramics prepared in Example 1. It can be seen from Figure 4 that the calcium fluoride crystal is granular and has a small particle size. Figure 5 Transmittance curve of the transparent glass-ceramics prepared in Comparative Example 2. It can be seen from Figure 5 that the visible light transmittance of Comparative Example 2 is 82%.

Claims

1. A transparent glass-ceramic, characterized in that, Its crystal phase includes a main crystal phase and a secondary crystal phase. The mass ratio of the main crystal phase is 70-98% of all crystal phases. The main crystal phase is a calcium fluoride crystal phase, and the mass of the calcium fluoride crystal phase accounts for 34-60% of the transparent glass-ceramics. The secondary crystal phase includes a lithium silicate crystal phase and / or a lithium disilicate crystal phase. The mass ratio of the lithium silicate crystal phase in the transparent glass-ceramics is less than 15%, and the mass ratio of the lithium disilicate crystal phase in the transparent glass-ceramics is less than 15%. The components of the transparent glass-ceramics, by mass fraction, include: SiO2: 30-50%; Al2O3: 15-30%; Li2O: 1-5%; Na2O: 2-6%; CaF2: 5-20%; ZrO2: 1-2%; lanthanide metal oxides: not exceeding 1%; B2O3: 0-3%; ZnO: 0-2%; MgO: 0-2%; P2O5: 0-7%; clarifying agent: 0-1%; the clarifying agent is one or more of Sb2O3, SnO2, and CeO2; the lanthanide metal oxides are one or more of Y2O3, Yb2O3, and La2O3. The mass ratio of CaF2 to lanthanide metal oxides is (20-140):1, the mass ratio of ZrO2 to lanthanide metal oxides is (1.5-15):1, the mass ratio of CaF2 to ZrO2 is (7-12):1, and the mass ratio of the total mass of Li2O + Na2O to CaF2 is (0.3-0.6):

1. The mass ratio of SiO2 to Al2O3 is (1.5-2):1, the mass ratio of the total mass of SiO2 + Al2O3 to Li2O is (13-20):1, and the mass ratio of Li2O to Na2O is (1-1.4):

1.

2. The transparent glass-ceramics according to claim 1, wherein The mass ratio of the main crystal phase is 77-90% of all crystal phases. The mass of the calcium fluoride crystal phase accounts for 43-60% of the transparent glass-ceramics. The secondary crystal phase includes a lithium silicate crystal phase and / or a lithium disilicate crystal phase. The mass ratio of the lithium silicate crystal phase in the transparent glass-ceramics is 2-12%, and the mass ratio of the lithium disilicate crystal phase in the transparent glass-ceramics is 1-10%.

3. The transparent glass-ceramics according to claim 1, characterized in that, The grain sizes of the main crystal phase and the secondary crystal phase are below 50 nm.

4. The transparent glass-ceramics according to claim 3, characterized in that, The grain sizes of the main crystal phase and the secondary crystal phase are below 35 nm.

5. The transparent glass-ceramics according to claim 1, characterized in that, Its components, by mass fraction, include: SiO2: 35-45%; Al2O3: 20-25%; Li2O: 2-5%; Na2O: 2.5-4%; CaF2: 9-16%; ZrO2: 1.5-2%; lanthanide metal oxides: 0.5-0.8%; B2O3: 0-2%; ZnO: 0-1.5%; MgO: 0-1.5%; P2O5: 1-7%; clarifying agent: 0-0.5%; the clarifying agent is one or more of Sb2O3, SnO2, and CeO2; the lanthanide metal oxides are one or more of Y2O3, Yb2O3, and La2O3.

6. The transparent glass-ceramics according to claim 1, characterized in that, The mass ratio of CaF2 to lanthanide metal oxides is (20-32):1, and the mass ratio of ZrO2 to lanthanide metal oxides is (1.8-4):

1.

7. A method for preparing a transparent glass-ceramics according to any one of claims 1-6, characterized in that, It includes the following steps: Prepare a base glass plate, and then perform crystallization treatment on the base glass plate by a two-step heat treatment method to obtain transparent glass-ceramics; the two-step heat treatment is to perform nucleation treatment at a first temperature and crystal growth treatment at a second temperature higher than the first temperature; The first temperature is 500-700°C, the second temperature is 650-850°C, the holding time at the first temperature is 1-10 h, and the holding time at the second temperature is 0.5-5 h.

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