High-crystallinity transparent lithium-aluminum-silicon microcrystalline glass and preparation method thereof

Abstract

The invention discloses high-crystallinity transparent lithium-aluminum-silicon microcrystalline glass and a preparation method thereof. The lithium-aluminum-silicon microcrystalline glass comprises the following oxide components in percentage by mole: 63 to 74 percent of SiO2, 3 to 10 percent of Al2O3, 12 to 21 percent of Li2O, 0.5 to 4 percent of MgO, 1 to 4 percent of ZrO2, 0.5 to 4 percent of P2O5, 0.1 to 2 percent of Sb2O3, 1 to 4 percent of Na2O and 0.1 to 2 percent of K2O. The principal crystalline phase of the prepared lithium-aluminum-silicon glass ceramic is LiAlSi4O10, the glass ceramic is transparent and has excellent mechanical properties, the size of crystals in the glass ceramic is within 100nm and the degree of crystallinity reaches more than 80% by using the composite nucleating agents ZrO2 and P2O5 and regulating and controlling the composition of oxides and a heat treatment system, and the application requirements of mobile terminal cover plate glass can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of glass preparation, and in particular relates to a high-crystallinity transparent lithium aluminum silicon glass-ceramic and a preparation method thereof. Background Art

[0002] As electronic information display devices are constantly updated, people have higher requirements for the drop resistance and scratch resistance of cover glass for display screens. Glass-ceramics has excellent mechanical properties such as high toughness and high hardness. The preparation of glass-ceramics that meet the transparent requirements is one of the future development directions of the electronic information display industry.

[0003] For glass-ceramics to be transparent, two conditions must be met: 1. There is no significant difference between the refractive index of the crystal and the refractive index of the glass phase; 2. The crystal size must be less than 100nm. The amount of crystal content directly determines the mechanical properties of glass-ceramics. Generally, the higher the crystal content, the better the mechanical properties. How to ensure that the crystal size in the glass-ceramics is small while precipitating more crystals is the key to improving the mechanical properties of glass-ceramics. Summary of the invention

[0004] The purpose of the present invention is to prepare a lithium aluminum silicon microcrystalline glass with high crystallinity and small crystal size, and improve the mechanical properties without affecting its transparency. Therefore, it is necessary to reasonably regulate the components, control the type of its crystal phase to ensure that the refractive index of the crystal is not significantly different from the refractive index of the glass phase; and regulate the type and ratio of the nucleating agent to ensure that the crystal size is less than 100nm while crystallizing as much as possible, thereby enhancing the mechanical properties of the microcrystalline glass.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A high-crystallinity transparent lithium aluminum silicon glass-ceramics, characterized in that the glass-ceramics is composed of the following oxides in molar percentage: SiO2: 63-74%, Al2O3: 3-10%, Li2O: 12-21%, MgO: 0.5-4%, ZrO2: 1-4%, P2O5: 0.5-4%, Sb2O3: 0.1-2%, Na2O: 1-4%, K2O: 0.1-2%; Among them, the value of (Li2O+ Al2O3) / SiO2 is 0.2~0.5; The value of (Li2O+ Na2O+K2O) / (SiO2+ Al2O3) is 0.1-0.4; The value of ZrO2 / P2O5 is 0.2~0.9.

[0006] Further technical solutions are: The microcrystalline glass is composed of the following oxides in molar percentages: SiO2: 66-72%, Al2O3: 4-8%, Li2O: 14-20%, MgO: 1-3%, ZrO2: 1-4%, P2O5: 0.5-3%, Sb2O3: 0.1-1%, Na2O: 1-3%, and K2O: 0.1-1%.

[0007] The value of (Li2O+Al2O3) / SiO2 is 0.2-0.4; the value of (Li2O+Na2O+K2O) / (SiO2+Al2O3) is 0.1-0.4; and the value of ZrO2 / P2O5 is 0.3-0.8.

[0008] The present invention also provides a method for preparing a highly crystallinity transparent lithium aluminum silicon glass-ceramics, comprising the following steps: (1) Raw material preparation: convert each oxide component into the introduced compound raw material according to the formula described in claim 1, 2 or 3, and fully mix each raw material in a mixer for 1 to 3 hours; (2) Melting: The mixed raw materials are placed in a platinum crucible, which is then placed in a high-temperature electric furnace. The temperature is raised to 1500-1600°C according to a step temperature system and kept at this temperature for 2-4 hours to obtain a clear glass liquid. (3) Forming annealing: The glass liquid is cast into a preheated copper mold and quickly transferred to an annealing furnace for annealing at 450-550℃ / min for 2h. After annealing, the glass is naturally cooled to obtain the base glass. (4) Heat treatment: Place the base glass in a crystallization furnace and heat it to 550-630°C for 2-10 hours for nucleation, then heat it to 660-720°C for 0.5-1.5 hours for crystallization to obtain lithium aluminum silicon glass-ceramics.

[0009] Furthermore, in step (4), the base glass is heated at a temperature of 5-10°C / min in the nucleation stage and at a temperature of 10-15°C / min in the crystallization stage.

[0010] The high-crystallinity transparent lithium aluminum silicon microcrystalline glass of the present invention has a crystallinity of more than 80% and a grain size of less than 100nm; the light transmittance of the lithium aluminum silicon microcrystalline glass at 550nm is more than 75%; and the Vickers hardness range of the lithium aluminum silicon microcrystalline glass is 6.5 to 7.4GPa.

[0011] The principle for selecting the role and content of each glass component in the formula of the present invention is: SiO4, Al2O3 and Li2O are the basic components of lithium aluminum silicon glass-ceramics.10 The crystallization content range is selected from the three contents, 63-74% SiO2, 3-10% Al2O3 and 12-21% Li2O to ensure the basic network structure and precipitated crystal phase types of the glass. MgO can improve the forming properties of the glass, and can also reduce the crystallization rate, prevent the crystal from growing too fast and causing the crystal size to be large. In the present invention, the molar percentage of MgO is 0.5-4%. Sb2O3 is used as a clarifier, which can effectively prevent the generation of bubbles in the glass during the melting process. In the present invention, 0.1-2% Sb2O3 has the best effect. The introduction of Na2O and K2O can adjust the glass network and provide conditions for the subsequent strengthening of microcrystalline glass. In the present invention, 1-4% Na2O and 0.1-2% K2O have better effects. ZrO2 and P2O5 are used as nucleating agents, among which ZrO2 mainly precipitates a micro-inhomogeneous area rich in ZrO2 in the glass matrix first, then induces glass nucleation, and makes crystals grow thereon. ZrO2 as a nucleating agent will not color the glass, but the solubility of ZrO2 in glass is limited and the melting point is relatively high. In the present invention, 1-4% ZrO2 has the best effect. P2O5 is used as a nucleating agent because P 5+ The ion field strength is large and it is easy to interact with R + or R 2+ The ions are separated from the glass network, which promotes glass phase separation, reduces interface energy and nucleation activation energy, and promotes crystal precipitation. In the present invention, 0.5-4% P2O5 has the best effect.

[0012] Compared with the prior art, the present invention has the following advantages: By adjusting the ratio of three oxides, SiO2, Al2O3 and Li2O, the crystal phase precipitated from lithium aluminum silicon glass-ceramics can ensure the transparency of glass-ceramics. By using ZrO2 and P2O5 composite nucleating agents, adjusting the ratio of ZrO2 and P2O5, and combining a specific heat treatment system, the crystal size of lithium aluminum silicon glass-ceramics is within 100nm, and the crystallinity reaches 80%; The prepared lithium aluminum silicon glass-ceramics ensures a transmittance of 80% while making the glass Vickers hardness reach 712GPa and the bending strength reach 608MPa, which can meet the application requirements of high-strength and wear-resistant mobile terminal glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is the X-ray diffraction pattern (XRD) of the glass-ceramics prepared in Example 7; Figure 2 This is a scanning electron microscope (SEM) image of the microcrystalline glass prepared in Example 7. DETAILED DESCRIPTION

[0014] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0015] The base glass and glass-ceramics of Examples 1 to 12 can be prepared by the following method: (1) Raw material preparation: Add the raw materials according to the proportions in Table 1 into a mixer and mix thoroughly for 2 hours; (2) Melting: The mixed raw materials are placed in a platinum crucible, and then the platinum crucible is placed in a high-temperature electric furnace. The temperature is first raised from room temperature to 800°C at a rate of 5°C / min, then raised from 800°C to 1300°C at a rate of 3°C / min, and then raised from 1300°C to 1560°C at a rate of 2°C / min. The temperature is kept at this temperature for 2 hours to obtain a clear glass liquid. (3) Forming annealing: The glass liquid is cast into a copper mold preheated at 600°C for 2 hours, and then the formed glass is quickly transferred to an annealing furnace and annealed at 500°C for 2 hours. After the annealing is completed, the base glass is naturally cooled to obtain; (4) Heat treatment: Place the base glass in a crystallization furnace and heat it to 570°C at 8°C / min and keep it warm for 8 hours for nucleation. After the nucleation is completed, heat it to 680°C at 15°C / min and keep it warm for 1 hour for crystallization to obtain lithium aluminum silicon microcrystalline glass.

[0016] The crystallinity, crystal size, transmittance, Vickers hardness and bending strength of lithium aluminum silicon glass-ceramics were tested respectively. The crystallinity was calculated by calculating the proportion of the diffraction intensity of the crystalline phase through the XRD test data; the crystal size was calculated by Nano Measurer using the SEM test data to calculate the grain size and distribution; the transmittance was tested on the glass-ceramics samples in the wavelength range of 200-1200 nm; the loading pressure for the Vickers hardness test was 1.96 N and the loading time was 15 s; the bending strength test was conducted using a four-point bending test with an upper span of 20 mm and a lower span of 40 mm.

[0017] Table 1

[0018] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form; any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A highly crystallinity transparent lithium aluminum silicon glass-ceramics, characterized in that: The microcrystalline glass is composed of the following oxides in molar percentages: SiO2: 63-74%, Al2O3: 3-10%, Li2O: 12-21%, MgO: 0.5-4%, ZrO2: 1-4%, P2O5: 0.5-4%, Sb2O3: 0.1-2%, Na2O: 1-4%, K2O: 0.1-2%; Among them, the value of (Li2O+ Al2O3) / SiO2 is 0.2~0.5; The value of (Li2O+ Na2O+K2O) / (SiO2+ Al2O3) is 0.1-0.4; The value of ZrO2 / P2O5 is 0.2~0.

9.

2. The highly crystallinity transparent lithium aluminum silicon glass-ceramics according to claim 1, characterized in that: The microcrystalline glass is composed of the following oxides in molar percentages: SiO2: 66-72%, Al2O3: 4-8%, Li2O: 14-20%, MgO: 1-3%, ZrO2: 1-4%, P2O5: 0.5-3%, Sb2O3: 0.1-1%, Na2O: 1-3%, and K2O: 0.1-1%.

3. The highly crystallinity transparent lithium aluminum silicon glass-ceramics according to claim 1, characterized in that: The value of (Li2O+Al2O3) / SiO2 is 0.2-0.4; the value of (Li2O+Na2O+K2O) / (SiO2+Al2O3) is 0.1-0.4; and the value of ZrO2 / P2O5 is 0.3-0.

8.

4. A method for preparing a highly crystallinity transparent lithium aluminum silicon glass-ceramics as described in claims 1-3, characterized in that The following steps are involved: (1) Raw material preparation: convert each oxide component into the introduced compound raw material according to the formula described in claim 1, 2 or 3, and fully mix each raw material in a mixer for 1 to 3 hours; (2) Melting: The mixed raw materials are placed in a platinum crucible, which is then placed in a high-temperature electric furnace. The temperature is raised to 1500-1600°C according to a step temperature system and kept at this temperature for 2-4 hours to obtain a clear glass liquid. (3) Forming annealing: The glass liquid is cast into a preheated copper mold and quickly transferred to an annealing furnace for annealing at 450-550℃ / min for 2h. After annealing, the glass is naturally cooled to obtain the base glass. (4) Heat treatment: Place the base glass in a crystallization furnace and heat it to 550-630°C for 2-10 hours for nucleation, then heat it to 660-720°C for 0.5-1.5 hours for crystallization to obtain lithium aluminum silicon glass-ceramics.

5. The method for preparing a highly crystallinity transparent lithium aluminum silicon glass-ceramics according to claim 4, characterized in that: In step (4), the base glass is heated at a temperature of 5-10°C / min in the nucleation stage and at a temperature of 10-15°C / min in the crystallization stage.

6. The highly crystallinity transparent lithium aluminum silicon glass-ceramics according to claim 5, characterized in that: The high-crystallinity transparent lithium aluminum silicon microcrystalline glass has a crystallinity of more than 80% and a grain size of less than 100nm; the light transmittance of the lithium aluminum silicon microcrystalline glass at 550nm is more than 75%; and the Vickers hardness range of the lithium aluminum silicon microcrystalline glass is 6.5 to 7.4GPa.

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