阅读说明：本技术 一种锂铝硅酸盐纳米晶玻璃陶瓷的强化方法 (Method for strengthening lithium aluminosilicate nanocrystalline glass ceramic ) 是由 张月皎 姚全星 罗恺 袁晓波 刘庆 李军旗 于 2019-09-09 设计创作，主要内容包括：一种锂铝硅酸盐纳米晶玻璃陶瓷的强化方法,包括以下步骤：提供一锂铝硅酸盐纳米晶玻璃陶瓷,所述锂铝硅酸盐纳米晶玻璃陶瓷为厚度不大于3mm的片状结构；对所述锂铝硅酸盐纳米晶玻璃陶瓷置于一预热炉中进行预热处理；将完成预热处理的所述锂铝硅酸盐纳米晶玻璃陶瓷由所述预热炉中取出,并置于一反应炉中进行强化处理,将所述锂铝硅酸盐纳米晶玻璃陶瓷放置于一第一熔盐中进行第一次强化,所述第一熔盐为至少包含钠离子的熔融状态盐类,所述锂铝硅酸盐纳米晶玻璃陶瓷中的锂离子与所述第一熔盐中的钠离子进行离子交换,所述第一次强化的时间为第一强化时间；完成第一次强化后将所述锂铝硅酸盐纳米晶玻璃陶瓷由所述反应炉取出并冷却。(A strengthening method of lithium aluminosilicate nanocrystalline glass ceramic comprises the following steps: providing a lithium aluminosilicate nanocrystalline glass ceramic, wherein the lithium aluminosilicate nanocrystalline glass ceramic is in a sheet structure with the thickness not more than 3 mm; placing the lithium aluminosilicate nanocrystalline glass ceramic in a preheating furnace for preheating treatment; taking the lithium aluminosilicate nanocrystalline glass ceramic subjected to preheating treatment out of the preheating furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic into a reaction furnace for strengthening treatment, placing the lithium aluminosilicate nanocrystalline glass ceramic into first molten salt for first strengthening, wherein the first molten salt is a molten salt at least containing sodium ions, the lithium ions in the lithium aluminosilicate nanocrystalline glass ceramic and the sodium ions in the first molten salt are subjected to ion exchange, and the first strengthening time is first strengthening time; and taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace after the first strengthening is completed, and cooling.)

1. A method for strengthening lithium aluminosilicate nanocrystalline glass ceramic is characterized by comprising the following steps:

Providing a lithium aluminosilicate nanocrystalline glass ceramic, wherein the lithium aluminosilicate nanocrystalline glass ceramic is in a sheet structure with the thickness not more than 3 mm;

Placing the lithium aluminosilicate nanocrystalline glass ceramic in a preheating furnace for preheating treatment;

Taking the lithium aluminosilicate nanocrystalline glass ceramic subjected to preheating treatment out of the preheating furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic into a reaction furnace for strengthening treatment, placing the lithium aluminosilicate nanocrystalline glass ceramic into first molten salt for first strengthening, wherein the first molten salt is a molten salt at least containing sodium ions, the lithium ions in the lithium aluminosilicate nanocrystalline glass ceramic and the sodium ions in the first molten salt are subjected to ion exchange, and the first strengthening time is first strengthening time; and

And taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace after the first strengthening is completed, and cooling.

2. The method for strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 1, further comprising the steps of:

Placing the cooled lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace for preheating treatment;

Taking the lithium aluminosilicate nanocrystalline glass ceramic subjected to preheating treatment out of the preheating furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic into a reaction furnace for strengthening treatment, placing the lithium aluminosilicate nanocrystalline glass ceramic into a second molten salt for strengthening for the second time, wherein the second molten salt is a molten state salt at least containing potassium ions, sodium ions in the lithium aluminosilicate nanocrystalline glass ceramic and potassium ions in the second molten salt are subjected to ion exchange, and the time of strengthening for the second time is the second strengthening time; and

And taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace after the second strengthening is completed, and cooling.

3. The method for strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 1 or 2, wherein the first molten salt is a molten-state salt further containing potassium ions, and sodium ions in the lithium aluminosilicate nanocrystalline glass-ceramic are ion-exchanged with potassium ions in the first molten salt.

4. The method for strengthening lithium aluminosilicate nanocrystalline glass ceramic according to claim 2, wherein the first molten salt is a molten salt further containing potassium ions, and the concentration of potassium ions in the first molten salt is smaller than the concentration of potassium ions in the second molten salt.

5. the method of strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 2, wherein the first strengthening time is greater than the second strengthening time.

6. The method for strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 2, wherein the first molten salt and the second molten salt contain lithium ions.

7. The method for strengthening lithium aluminosilicate nanocrystalline glass ceramic according to any one of claims 1 to 2 and 4 to 5, characterized in that the temperature range of the ion exchange of the lithium aluminosilicate nanocrystalline glass ceramic with the first molten salt is 350 ℃ to 600 ℃, and the temperature range of the ion exchange of the lithium aluminosilicate nanocrystalline glass ceramic with the second molten salt is 350 ℃ to 600 ℃.

8. The method for strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 7, characterized in that the step of cooling the nanocrystalline ceramic material is: and directly taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace, and physically cooling the lithium aluminosilicate nanocrystalline glass ceramic to cool the lithium aluminosilicate nanocrystalline glass ceramic to room temperature.

9. the method for strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 7, characterized in that the step of cooling the nanocrystalline ceramic material is: taking the lithium aluminosilicate nanocrystalline glass ceramic out of the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic above the reaction furnace in a hanging manner for 2-10 minutes to enable molten state salts on the surface of the lithium aluminosilicate nanocrystalline glass ceramic to drip back into the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace to be cooled to be not higher than 100 ℃, and taking the lithium aluminosilicate nanocrystalline glass ceramic out of the preheating furnace and cooling to room temperature.

10. The method for strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 7, characterized in that the step of cooling the nanocrystalline ceramic material is: taking the lithium aluminosilicate nanocrystalline glass ceramic out of the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic above the reaction furnace in a hanging manner for 2-10 minutes to enable molten state salts on the surface of the lithium aluminosilicate nanocrystalline glass ceramic to drip back into the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace to be cooled to 250-300 ℃, taking the lithium aluminosilicate nanocrystalline glass ceramic out of the preheating furnace, physically cooling the lithium aluminosilicate nanocrystalline glass ceramic, and cooling the lithium aluminosilicate nanocrystalline glass ceramic to room temperature.

11. The method for strengthening lithium aluminosilicate nanocrystalline glass-ceramic according to claim 7, characterized in that the step of cooling the nanocrystalline ceramic material is: taking the lithium aluminosilicate nanocrystalline glass ceramic out of the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic above the reaction furnace in a hanging manner for 10-30 minutes to enable molten state salts on the surface of the lithium aluminosilicate nanocrystalline glass ceramic to drip back into the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace to be cooled at a constant temperature within the temperature range of 300-400 ℃, then naturally cooling the lithium aluminosilicate nanocrystalline glass ceramic to be not more than 100 ℃, and then taking the lithium aluminosilicate nanocrystalline glass ceramic out of the preheating furnace and cooling to room temperature.

Technical Field

The invention relates to the field of chemical industry, in particular to a method for strengthening lithium aluminosilicate nanocrystalline glass ceramic.

Background

Nanocrystalline glass-ceramics are a multiphase composite material that combines a dense nanocrystalline phase (crystalline phase) with a glassy phase. After the base glass with specific composition is heat treated, the glass liquid phase generates nucleus and grows crystal, and the composite material with homogeneous nanometer crystal phase and glass phase is further produced. The nano-crystalline glass ceramic has excellent performance, on one hand, the nano-crystalline glass ceramic has the characteristics of high strength, high hardness and the like of the ceramic, and the nano-crystalline glass ceramic has good wear resistance and corrosion resistance, strong impact resistance and stable chemical performance; on the other hand, the nanocrystalline glass ceramic has high permeability of glass, and can realize curved surface molding by using a thermal molding process. The nanocrystalline glass ceramic can be widely applied to screen cover plates and back plates of intelligent products such as smart phones, smart watches, tablet computers, automobile central control protection screens and the like, and can also be widely applied to microscopes, digital cameras, projectors and various optical lenses.

Due to the particularity of the components of the lithium aluminosilicate nanocrystalline glass ceramic, the lithium aluminosilicate nanocrystalline glass ceramic has crystal structures such as beta-quartz, lithium disilicate and the like, so that the lithium aluminosilicate nanocrystalline glass ceramic can obtain the properties superior to other glass ceramics, such as low expansion, even zero expansion, high-temperature stability, high strength and the like. However, the lithium aluminosilicate nanocrystalline glass ceramic has special components, so that the traditional strengthening method has poor effect. It is considered by those skilled in the art how to provide a method for strengthening lithium aluminosilicate nanocrystalline glass ceramics.

Disclosure of Invention

In view of the above, the present invention provides a method for strengthening lithium aluminosilicate nanocrystalline glass ceramic.

The invention provides a method for strengthening lithium aluminosilicate nanocrystalline glass ceramics, which comprises the following steps:

Providing a lithium aluminosilicate nanocrystalline glass ceramic, wherein the lithium aluminosilicate nanocrystalline glass ceramic is in a sheet structure with the thickness not more than 3 mm;

Placing the lithium aluminosilicate nanocrystalline glass ceramic in a preheating furnace for preheating treatment;

Taking the lithium aluminosilicate nanocrystalline glass ceramic subjected to preheating treatment out of the preheating furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic into a reaction furnace for strengthening treatment, placing the lithium aluminosilicate nanocrystalline glass ceramic into first molten salt for first strengthening, wherein the first molten salt is a molten salt at least containing sodium ions, the lithium ions in the lithium aluminosilicate nanocrystalline glass ceramic and the sodium ions in the first molten salt are subjected to ion exchange, and the first strengthening time is first strengthening time; and

And taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace after the first strengthening is completed, and cooling.

further, the method also comprises the following steps:

Placing the cooled lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace for preheating treatment;

Taking the lithium aluminosilicate nanocrystalline glass ceramic subjected to preheating treatment out of the preheating furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic into a reaction furnace for strengthening treatment, placing the lithium aluminosilicate nanocrystalline glass ceramic into a second molten salt for strengthening for the second time, wherein the second molten salt is a molten state salt at least containing potassium ions, sodium ions in the lithium aluminosilicate nanocrystalline glass ceramic and potassium ions in the second molten salt are subjected to ion exchange, and the time of strengthening for the second time is the second strengthening time; and

And taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace after the second strengthening is completed, and cooling.

Further, the first molten salt is a molten salt further comprising potassium ions, and sodium ions in the lithium aluminosilicate nanocrystalline glass ceramic are ion exchanged with potassium ions in the first molten salt.

Further, the first molten salt is a molten salt further containing potassium ions, and the concentration of potassium ions in the first molten salt is smaller than the concentration of potassium ions in the second molten salt.

Further, the first reinforcement time is greater than the second reinforcement time.

Further, the first molten salt and the second molten salt contain lithium ions.

Further, the temperature ranges of the ion exchange between the lithium aluminosilicate nanocrystalline glass ceramic and the first molten salt are both 350 ℃ to 600 ℃, and the temperature ranges of the ion exchange between the lithium aluminosilicate nanocrystalline glass ceramic and the second molten salt are both 350 ℃ to 600 ℃.

Further, the step of cooling the nanocrystalline ceramic material comprises: and directly taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace, and physically cooling the lithium aluminosilicate nanocrystalline glass ceramic sheet to cool the lithium aluminosilicate nanocrystalline glass ceramic to room temperature.

further, the step of cooling the nanocrystalline ceramic material comprises: taking the lithium aluminosilicate nanocrystalline glass ceramic out of the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic above the reaction furnace in a hanging manner for 2-10 minutes to enable molten state salts on the surface of the lithium aluminosilicate nanocrystalline glass ceramic to drip back into the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace to be cooled to be not higher than 100 ℃, and taking the lithium aluminosilicate nanocrystalline glass ceramic out of the preheating furnace and cooling to room temperature.

Further, the step of cooling the nanocrystalline ceramic material comprises: taking the lithium aluminosilicate nanocrystalline glass ceramic out of the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic above the reaction furnace in a hanging manner for 2-10 minutes to enable molten state salts on the surface of the lithium aluminosilicate nanocrystalline glass ceramic to drip back into the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace to be cooled to 250-300 ℃, taking the lithium aluminosilicate nanocrystalline glass ceramic out of the preheating furnace, physically cooling the lithium aluminosilicate nanocrystalline glass ceramic, and cooling the lithium aluminosilicate nanocrystalline glass ceramic to room temperature.

Further, the step of cooling the nanocrystalline ceramic material comprises: taking the lithium aluminosilicate nanocrystalline glass ceramic out of the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic above the reaction furnace in a hanging manner for 10-30 minutes to enable molten state salts on the surface of the lithium aluminosilicate nanocrystalline glass ceramic to drip back into the reaction furnace, placing the lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace to be cooled at a constant temperature within the temperature range of 300-400 ℃, then naturally cooling the lithium aluminosilicate nanocrystalline glass ceramic to be not more than 100 ℃, and then taking the lithium aluminosilicate nanocrystalline glass ceramic out of the preheating furnace and cooling to room temperature.

The strengthening method of the lithium aluminosilicate nanocrystalline glass ceramic comprises a primary strengthening method and a secondary strengthening method. The strengthened lithium aluminosilicate nanocrystalline glass ceramic material sheet with the thickness of less than 3mm has the characteristics that the property is obviously improved, the maximum surface compressive stress value CS1 is more than 700MPa, the inflection point surface compressive stress value CS2 is more than 100MPa, the inflection point stress layer depth DOL2 is more than 6 mu m, the maximum stress layer depth DOL1 is more than 40 mu m, the central maximum tensile stress layer CT is less than 120MPa, and the strengthened Vickers hardness reaches 800kgf/mm²Impact resistance greater than 2J and high breaking strengthThe degree is more than 700 MPa.

Drawings

Fig. 1 is a schematic flow chart of a primary strengthening method of a lithium aluminosilicate nanocrystalline glass ceramic according to an embodiment of the present invention.

Fig. 2 is a schematic flow chart of a secondary strengthening method of a lithium aluminosilicate nanocrystalline glass ceramic according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of the compressive stress of the lithium aluminosilicate nanocrystalline glass ceramic of the present invention after being strengthened by the secondary strengthening method

Description of the main elements

Step (ii) of	S101～S107、S201～S212
		value of compressive stress	CS1、CS2
depth of stress	DOL1、DOL2

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention and the scope of the present invention is therefore not limited to the specific embodiments disclosed below.

the lithium aluminosilicate nanocrystalline glass ceramic of the invention comprises the following raw materials by weight percent:

Lithium oxide (Li)₂o) 5% -15%, silicon dioxide (SiO)₂) 40-80% of aluminum oxide (Al)₂O₃) 10-35 percent of magnesium oxide (MgO), 0-20 percent of zinc oxide (ZnO), 0-10 percent of potassium oxide (K)₂O) 0% -10%, sodium oxide (Na)₂0 to 15 percent of O), 0 to 5 percent of calcium oxide (CaO), and ferric oxide (Fe)₂O₃) 0% -5% of chromium oxide (Cr)₂O₃)0-5 percent of nickel oxide (NiO), 0-5 percent of phosphorus oxide (P)₂O₅) 0% -10% of titanium dioxide (TiO)₂) 0% -15% of zirconium dioxide (ZrO)₂) 0% -10% of tin dioxide (SnO)₂) 0% -5% of niobium pentoxide (Nb)₂O₅) 0% -5%, antimony oxide (Sb)₂O₃) 0-5%, barium oxide (BaO) 0-5% and trace silver (Ag).

Wherein Li₂O is used for replacing potassium oxide or sodium oxide in the traditional nanocrystalline glass ceramic, and Li₂o can adjust the coefficient of thermal expansion of the material to produce low or zero expansion nanocrystalline glass-ceramics for special optical applications. Li₂The content of O can also control the crystallization tendency of the material, Li₂O can also reduce the melting temperature and viscosity of the material to a certain extent, thereby reducing the difficulty of subsequent curved surface forming of the material, Li₂The percentage by weight of O may be between 5% and 15%.

wherein, SiO₂SiO, the basic skeleton for forming lithium aluminosilicate nanocrystalline glass ceramics₂Too low a content may destabilize or coarsen the crystalline phase generated in the lithium aluminosilicate nanocrystalline glass ceramic and may cause the lithium aluminosilicate nanocrystalline glass ceramic to lack gloss or even to devitrify, while SiO₂Too high a content may make the raw material difficult to melt, so that the preparation process of the lithium aluminosilicate nanocrystalline glass ceramic requires a higher melting temperature, and therefore, SiO₂the weight percentage of the components is controlled to be between 40 and 80 percent.

Among them, BaO can be used to increase the refractive index, density, gloss and chemical stability of the lithium aluminosilicate nanocrystalline glass ceramic, but when the BaO content is too high, it may cause the lithium aluminosilicate nanocrystalline glass ceramic material to be not clear, and therefore, the weight percentage of BaO should be controlled between 0% and 5%.

wherein, Al₂O₃Can be used to increase the mechanical strength and stability of lithium aluminosilicate nanocrystalline glass ceramics, however, when Al is used₂O₃Too high a content may cause difficulty in the melting process of the lithium aluminosilicate nanocrystalline glass ceramic or a decrease in devitrification resistance thereof, and therefore, Al₂O₃The weight percentage of the components is controlled to be between 10 and 35 percent.

the MgO can be used for enabling the lithium aluminosilicate nanocrystalline glass ceramic to form a high-strength stable crystalline phase, and the proper amount of the MgO can be added to enhance the mechanical strength and the chemical stability of the lithium aluminosilicate nanocrystalline glass ceramic, so that the weight percentage of the MgO can be between 0 and 20 percent.

Wherein, ZnO can be used for improving the chemical stability of the lithium aluminosilicate nanocrystalline glass ceramic, and can be used for reducing the softening point temperature of the lithium aluminosilicate nanocrystalline glass ceramic, which is beneficial to the melting preparation process of the lithium aluminosilicate nanocrystalline glass ceramic, but the high ZnO content can cause the crystal phase variety to change greatly, further leading the stable crystal grain not to be formed, therefore, the weight percentage of ZnO should be controlled between 0 percent and 10 percent.

Wherein, K₂O、Na₂O can be used as a good cosolvent, can be an oxide outside a lithium aluminosilicate nanocrystalline glass ceramic structure network, and can effectively reduce the viscosity of the lithium aluminosilicate nanocrystalline glass ceramic so as to reduce the melting temperature. However, excessive Na₂the thermal expansion coefficient of the lithium aluminosilicate nanocrystalline glass ceramic is increased by O, and the mechanical strength and the chemical stability of the lithium aluminosilicate nanocrystalline glass ceramic are reduced; k₂o can increase the transparency and gloss of lithium aluminosilicate nanocrystalline glass ceramics, but the content of K is too high₂O reduces the devitrification ability of the lithium aluminosilicate nanocrystalline glass ceramic, and thus, K₂The weight percentage of O is controlled between 0 percent and 10 percent, Na₂The weight percentage of O is controlled between 0% and 15%.

wherein, CaO can be used as a good cosolvent and a stabilizer, can be an oxide outside a lithium aluminosilicate nanocrystalline glass ceramic structure network, and can effectively reduce the viscosity of the lithium aluminosilicate nanocrystalline glass ceramic so as to reduce the melting temperature. However, excessive CaO may lead to a reduction in glass fritness, an increase in brittleness, and an increase in crystallization tendency of the lithium aluminosilicate nanocrystalline glass ceramic, and thus the weight percentage of CaO should be controlled between 0% and 5%.

Wherein Nb₂O₅can be used for improving the chemical stability and thermal stability of lithium aluminosilicate nanocrystalline glass ceramics and simultaneously reducing the softening point thereof, and therefore, Nb₂O₅The weight percentage of the components is controlled to be between 0 and 5 percent.

Wherein, Fe₂O₃Can be used as a crystal nucleus agent, Fe₂O₃Precipitation and formation of nanocrystalline phases may be promoted, however, Fe₂O₃Too high a content may result in a deterioration of the compactness of the material and a decrease in the chemical stability of the material, and therefore, Fe₂O₃the weight percentage of the components is controlled to be between 0 and 5 percent.

wherein, Cr₂O₃Can be used as a crystal nucleus agent, Cr₂O₃Precipitation and formation of nanocrystalline phases may be promoted, however, Cr₂O₃The inclusion of chromium has a coloring effect which affects the transparency of the lithium aluminosilicate nanocrystalline glass ceramic, and therefore, Cr₂O₃the weight percentage of the components is controlled to be between 0 and 5 percent.

Wherein, P₂O₅can be used as a crystal nucleus agent, P₂O₅Can promote the precipitation and formation of nanocrystalline phase and prevent excessive grain growth, and can improve the dispersion coefficient and transmittance of lithium aluminosilicate nanocrystalline glass ceramic, but with excessive content of P₂O₅The material thermal expansion coefficient is increased because the lithium aluminosilicate nanocrystalline glass ceramic generates a white turbidity phenomenon and is devitrified, so that P₂O₅The weight percentage of the components is controlled to be between 0 and 10 percent.

Wherein, TiO₂Can be used as a crystal nucleus agent, TiO₂Can promote the precipitation and formation of nanocrystalline phase and increaseHomogeneity of lithium-added aluminosilicate nanocrystalline glass ceramics, but too high a content of TiO₂May cause devitrification of the lithium aluminosilicate nanocrystalline glass ceramic and, therefore, of the TiO₂The weight percentage of the components is controlled to be between 0 and 15 percent.

Wherein, ZrO₂Can be used as a nucleating agent, ZrO₂Can promote the precipitation and formation of nanocrystalline phase and make the crystal grain fine, further can increase the mechanical strength and chemical stability of the lithium aluminosilicate nanocrystalline glass ceramic, but the content of TiO is too high₂May cause difficulty in melting the raw material, and thus, ZrO₂The weight percentage of the components is controlled to be between 0 and 10 percent.

Wherein Sb₂O₃、As₂O₃、SnO₂Can be used as clarifier, Sb₂O₃、As₂O₃、SnO₂Is favorable for promoting the discharge of bubbles in the process of melting raw materials, further improves the compactness of the lithium aluminosilicate nanocrystalline glass ceramic, and Sb₂O₃、As₂O₃、SnO₂May be between 0% and 5% by weight.

Wherein Ag can also be used as a crystal nucleus agent.

In one embodiment, the lithium aluminosilicate nanocrystalline glass ceramic may be LiO-containing₂LiO of (2)₂-Al₂O₃-SiO₂The nanocrystalline glass-ceramic of the system, the crystalline phase of the lithium aluminosilicate nanocrystalline glass-ceramic may comprise 2SiO₂-Li₂Lithium O-disilicate, nepheline, spinel, cordierite, beta-quartz, beta-spodumene, and the like.

The raw materials can be mixed according to the proportion to prepare the lithium aluminosilicate nanocrystalline glass ceramic, and the prepared lithium aluminosilicate nanocrystalline glass ceramic can be strengthened by a strengthening method to enhance the performance of the lithium aluminosilicate nanocrystalline glass ceramic.

As shown in FIG. 1, the present invention provides a primary strengthening method of lithium aluminosilicate nanocrystalline glass ceramic:

Step S101: and cutting, polishing and cleaning the lithium aluminosilicate nanocrystalline glass ceramic.

Specifically, after polishing and grinding, the lithium aluminosilicate nanocrystalline glass ceramic is cut into lithium aluminosilicate nanocrystalline glass ceramic sheets with the thickness not more than 3mm, the lithium aluminosilicate nanocrystalline glass ceramic sheets are polished, then the lithium aluminosilicate nanocrystalline glass ceramic sheets are placed in a cleaning clamping groove and are placed in a cleaning machine for cleaning for 30-60 minutes, and the sheets are taken out after cleaning.

Step S102: transferring the lithium aluminosilicate nanocrystalline glass ceramic into a fixing frame, and placing the fixing frame provided with the lithium aluminosilicate nanocrystalline glass ceramic into a bearing basket.

Specifically, the cleaned lithium aluminosilicate nanocrystalline glass ceramic sheet is moved to a tempering fixing frame from a cleaning clamping groove, the tempering fixing frame provided with the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed into a bearing hanging basket of the strengthening equipment, and the bearing hanging basket can bear materials and enter a strengthening preheating furnace and a reaction furnace.

Step S103: and placing the lithium aluminosilicate nanocrystalline glass ceramic into a preheating furnace for preheating treatment.

Specifically, the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in a preheating furnace and is preheated for 40 to 120 minutes at a temperature ranging from 320 ℃ to 400 ℃.

Step S104: and placing the lithium aluminosilicate nanocrystalline glass ceramic into first molten salt in the reaction furnace for first strengthening.

Specifically, the preheated lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in a reaction furnace, and is immersed in first molten salt for ion exchange, wherein the first strengthening temperature (temperature range of the ion exchange process) is 350 ℃ to 600 ℃, and the first strengthening time (ion exchange holding time) is 120 to 600 minutes.

The first molten salt is a molten salt, and the salt ratio can be as follows:

The first proportioning: pure sodium nitrate (NaNO)₃)，NaNO₃The purity of (A) is more than 99.9%;

And a third ratio: 50% -99.9 wt% potassium nitrate (KNO)₃) 0.1-50 wt% of sodium nitrate (NaNO)₃) And 0-5 wt% of additives and catalysts;

And a fourth ratio: 0.1-50 wt% potassium nitrate (KNO)₃) 50 to 99.9 weight percent of sodium nitrate (NaNO)₃) And 0-5 wt% of additives and catalysts.

and a fifth proportioning: 50-99.9 wt% potassium nitrate (KNO)₃) 1-50 wt% of sodium nitrate (NaNO)₃) 1-50 wt% of lithium nitrate (LiNO)₃) And 0-5.0 wt% of additives and catalysts.

and sixth proportioning: 1-50 wt% potassium (KNO)₃) 50 wt% -99.9 wt% of sodium nitrate (NaNO)₃) 1-50 wt% of lithium nitrate (LiNO)₃) And 0-5.0 wt% of additives and catalysts.

The lithium aluminosilicate nanocrystalline glass ceramic sheet can be placed in a first molten salt with any one of the first proportion, the third proportion and the sixth proportion for ion exchange, wherein potassium nitrate in the proportion can be replaced by other salts containing potassium ions, such as potassium sulfate, potassium chloride and the like, sodium nitrate can be replaced by other salts containing sodium ions, such as sodium sulfate, sodium chloride and the like, and lithium nitrate can be replaced by other salts containing lithium ions, such as lithium sulfate, lithium chloride and the like.

In the ion exchange process, sodium ions in the molten salt exchange with lithium ions in the lithium aluminosilicate nanocrystalline glass ceramic, so that the stress layer has larger stress layer depth DOL 1.

lithium ions, sodium ions and potassium ions in the lithium aluminosilicate nanocrystalline glass ceramic and the molten salt are exchanged, so that a surface compressive stress layer is formed on the surface of the lithium aluminosilicate nanocrystalline glass ceramic, and a larger compressive stress value CS1 and smaller DOL2 and CS2 are formed on the surface of the lithium aluminosilicate nanocrystalline glass ceramic.

In the primary strengthening process, lithium ions such as lithium nitrate and the like can be added into the molten salt, so that the concentration of sodium and potassium is reduced, and the exchange depth is deepened.

Step S105: and taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace after the first strengthening is completed, and cooling.

Specifically, after the first strengthening is completed, the carrying basket carrying the lithium aluminosilicate nanocrystalline glass ceramic sheet is taken out of the reaction furnace and cooled, and the cooling process may include the following four cooling methods:

The first cooling method: rapidly cooling, namely directly taking out the bearing hanging basket from the reaction furnace without placing the bearing hanging basket in a preheating furnace, and physically cooling the lithium aluminosilicate nanocrystalline glass ceramic sheet by using a fan, wherein the temperature of the lithium aluminosilicate nanocrystalline glass ceramic sheet is rapidly reduced to room temperature;

The second cooling method: naturally cooling, taking out the bearing hanging basket bearing the lithium aluminosilicate nanocrystalline glass ceramic sheet from the reaction furnace, taking out the lithium aluminosilicate nanocrystalline glass ceramic sheet from the reaction furnace, suspending and placing the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and enabling the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, the process can avoid the waste of salts in a molten state on one hand, and can avoid the excessive salt generated on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet on the other hand, the salt dripping time is 2-10 minutes, then the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in the preheating furnace for cooling, then the temperature is reduced to be below 100 ℃ in a natural cooling mode, then a preheating furnace door is opened, the bearing hanging basket is taken out, and the lithium aluminosilicate nanocrystalline glass ceramic sheet is allowed to stand to the room temperature;

The third cooling method: gradient cooling, namely taking the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, suspending the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and enabling molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, wherein in the process, on one hand, the molten salt can be prevented from being wasted, and on the other hand, excessive salt can be prevented from being generated on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet, the salt dropping time is 2-10 minutes, the temperature is reduced to 250-300 ℃ in a natural cooling mode, then a hanging basket bearing material is taken out of the furnace, a fan is used for physically cooling the lithium aluminosilicate nanocrystalline glass ceramic sheet, and the temperature of the lithium aluminosilicate nanocrystalline glass ceramic sheet is rapidly reduced to room temperature;

The fourth cooling method: annealing, taking the bearing hanging basket bearing the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, taking the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, suspending and placing the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and allowing molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, wherein the process can avoid waste of molten salt on one hand, and can avoid excessive salt on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet on the other hand, the salt dropping time is 2-10 minutes, and then the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed into the preheating furnace to be cooled, the preheating furnace is at a constant temperature, the temperature range in the preheating furnace is 300-400 ℃, and after the molten salt dropping is completed, the temperature is reduced to below 100 ℃ in a natural cooling mode, and then opening a preheating furnace door, taking out the bearing hanging basket, and allowing the lithium aluminosilicate nanocrystalline glass ceramic sheet to stand to room temperature.

The strengthening time of the lithium aluminosilicate nanocrystalline glass ceramic can be prolonged through the cooling and annealing processes, and the depth of ion exchange is increased.

Step S106: and cleaning the lithium aluminosilicate nanocrystalline glass ceramic to remove the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic.

Specifically, the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a water bath to remove the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic, and the water bath mode for dissolving the molten salt at least comprises the following 3 modes:

the first water bath mode: placing the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic in a hot water bath with the temperature range of 50-70 ℃ for soaking or spraying for 20-60 minutes;

the second water bath mode: placing the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic in a cold water bath at the temperature of 15-35 ℃ for soaking or spraying for 20-60 minutes;

the third water bath mode: firstly, the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a hot water bath with the temperature range of 50-70 ℃ for soaking or spraying for 20-60 minutes, and then the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a cold water bath with the temperature range of 15-35 ℃ for soaking or spraying for 20-60 minutes.

Step S107: and drying the lithium aluminosilicate nanocrystalline glass ceramic.

Specifically, the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is taken out from the water bath, and is kept stand for 20-30 minutes for water filtration until water stains are filtered out.

As shown in FIG. 2, the present invention provides a secondary strengthening method of lithium aluminosilicate nanocrystalline glass ceramic:

step S201: and cutting, polishing and cleaning the lithium aluminosilicate nanocrystalline glass ceramic.

Specifically, after polishing and grinding, the lithium aluminosilicate nanocrystalline glass ceramic is cut into lithium aluminosilicate nanocrystalline glass ceramic sheets with the thickness not more than 3mm, the lithium aluminosilicate nanocrystalline glass ceramic sheets are polished, then the lithium aluminosilicate nanocrystalline glass ceramic sheets are placed in a cleaning clamping groove and are placed in a cleaning machine for cleaning for 30-60 minutes, and the sheets are taken out after cleaning.

Step S202: transferring the lithium aluminosilicate nanocrystalline glass ceramic into a fixing frame, and placing the fixing frame provided with the lithium aluminosilicate nanocrystalline glass ceramic into a bearing basket.

specifically, the cleaned lithium aluminosilicate nanocrystalline glass ceramic sheet is moved to a tempering fixing frame from a cleaning clamping groove, the tempering fixing frame provided with the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed into a bearing hanging basket of the strengthening equipment, and the bearing hanging basket can bear materials and enter a strengthening preheating furnace and a reaction furnace.

Step S203: and placing the lithium aluminosilicate nanocrystalline glass ceramic into a preheating furnace for preheating treatment.

specifically, the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in a preheating furnace and is preheated for 40 to 120 minutes at a temperature ranging from 320 ℃ to 400 ℃.

Step S204: and placing the lithium aluminosilicate nanocrystalline glass ceramic into the molten salt of the reaction furnace for primary reinforcement.

Specifically, the preheated lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in a reaction furnace, and is immersed in first molten salt for ion exchange, wherein the first strengthening temperature (temperature range of the ion exchange process) is 350 ℃ to 600 ℃, and the first strengthening time (ion exchange holding time) is 120 to 600 minutes.

The first molten salt is a molten salt, and the salt ratio can be as follows:

The first proportioning: pure sodium nitrate (NaNO)₃)，NaNO₃The purity of (A) is more than 99.9%;

And a third ratio: 50% -99.9 wt% potassium nitrate (KNO)₃) 0.1-50 wt% of sodium nitrate (NaNO)₃) And 0-5 wt% of additives and catalysts;

And a fourth ratio: 0.1-50 wt% potassium nitrate (KNO)₃) 50 to 99.9 weight percent of sodium nitrate (NaNO)₃) And 0-5 wt% of additives and catalysts.

And a fifth proportioning: 50-99.9 wt% potassium nitrate (KNO)₃) 1-50 wt% of sodium nitrate (NaNO)₃) 1-50 wt% of lithium nitrate (LiNO)₃) And 0-5.0 wt% of additives and catalysts.

and sixth proportioning: 1-50 wt% potassium (KNO)₃) 50 wt% -99.9 wt% of sodium nitrate (NaNO)₃) 1-50 wt% of lithium nitrate (LiNO)₃) And 0-5.0 wt% of additives and catalysts.

The lithium aluminosilicate nanocrystalline glass ceramic sheet can be placed in a first molten salt with any one of the first proportion, the third proportion and the sixth proportion for ion exchange, wherein potassium nitrate in the proportion can be replaced by other salts containing potassium ions, such as potassium sulfate, potassium chloride and the like, sodium nitrate can be replaced by other salts containing sodium ions, such as sodium sulfate, sodium chloride and the like, and lithium nitrate can be replaced by other salts containing lithium ions, such as lithium sulfate, lithium chloride and the like.

In the ion exchange process, sodium ions in the molten salt exchange with lithium ions in the lithium aluminosilicate nanocrystalline glass ceramic, so that the stress layer has larger stress layer depth DOL 1.

Step S205: and taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace after the first strengthening is completed, and cooling.

Specifically, after the first strengthening is completed, the carrying basket carrying the lithium aluminosilicate nanocrystalline glass ceramic sheet is taken out of the reaction furnace and cooled, and the cooling process may include the following four cooling methods:

The first cooling method: rapidly cooling, namely directly taking out the bearing hanging basket from the reaction furnace without placing the bearing hanging basket in a preheating furnace, and physically cooling the lithium aluminosilicate nanocrystalline glass ceramic sheet by using a fan, wherein the temperature of the lithium aluminosilicate nanocrystalline glass ceramic sheet is rapidly reduced to room temperature;

The second cooling method: naturally cooling, taking out the bearing hanging basket bearing the lithium aluminosilicate nanocrystalline glass ceramic sheet from the reaction furnace, taking out the lithium aluminosilicate nanocrystalline glass ceramic sheet from the reaction furnace, suspending and placing the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and enabling the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, the process can avoid the waste of salts in a molten state on one hand, and can avoid the excessive salt generated on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet on the other hand, the salt dripping time is 2-10 minutes, then the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in the preheating furnace for cooling, then the temperature is reduced to be below 100 ℃ in a natural cooling mode, then a preheating furnace door is opened, the bearing hanging basket is taken out, and the lithium aluminosilicate nanocrystalline glass ceramic sheet is allowed to stand to the room temperature;

The third cooling method: gradient cooling, namely taking the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, suspending the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and enabling molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, wherein in the process, on one hand, the molten salt can be prevented from being wasted, and on the other hand, excessive salt can be prevented from being generated on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet, the salt dropping time is 2-10 minutes, the temperature is reduced to 250-300 ℃ in a natural cooling mode, then a hanging basket bearing material is taken out of the furnace, a fan is used for physically cooling the lithium aluminosilicate nanocrystalline glass ceramic sheet, and the temperature of the lithium aluminosilicate nanocrystalline glass ceramic sheet is rapidly reduced to room temperature;

the fourth cooling method: annealing, taking the bearing hanging basket bearing the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, taking the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, suspending and placing the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and allowing molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, wherein the process can avoid waste of molten salt on one hand, and can avoid excessive salt on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet on the other hand, the salt dropping time is 2-10 minutes, and then the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed into the preheating furnace to be cooled, the preheating furnace is at a constant temperature, the temperature range in the preheating furnace is 300-400 ℃, and after the molten salt dropping is completed, the temperature is reduced to below 100 ℃ in a natural cooling mode, and then opening a preheating furnace door, taking out the bearing hanging basket, and allowing the lithium aluminosilicate nanocrystalline glass ceramic sheet to stand to room temperature.

Step S206: and cleaning the lithium aluminosilicate nanocrystalline glass ceramic to remove the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic.

specifically, the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a water bath to remove the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic, and the water bath mode for dissolving the molten salt at least comprises the following 3 modes:

The first water bath mode: placing the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic in a hot water bath with the temperature range of 50-70 ℃ for soaking or spraying for 20-60 minutes;

The second water bath mode: placing the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic in a cold water bath at the temperature of 15-35 ℃ for soaking or spraying for 20-60 minutes;

The third water bath mode: firstly, the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a hot water bath with the temperature range of 50-70 ℃ for soaking or spraying for 20-60 minutes, and then the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a cold water bath with the temperature range of 15-35 ℃ for soaking or spraying for 20-60 minutes.

Step S207: and drying the lithium aluminosilicate nanocrystalline glass ceramic.

Specifically, the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is taken out from the water bath, and is kept stand for 20-30 minutes for water filtration until water stains are filtered out.

Step S208: and placing the lithium aluminosilicate nanocrystalline glass ceramic in the preheating furnace for preheating treatment.

Specifically, the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in a preheating furnace and is preheated for 40 to 120 minutes at a temperature ranging from 320 ℃ to 400 ℃.

Step S209: and placing the lithium aluminosilicate nanocrystalline glass ceramic in the molten salt of the reaction furnace for secondary strengthening.

Specifically, the preheated lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in a reaction furnace, and is immersed in a second molten salt for ion exchange, wherein the second strengthening temperature (the temperature range of the ion exchange process) is 350 ℃ to 600 ℃, and the second strengthening time (the ion exchange holding time) is 10 minutes to 200 minutes.

The second molten salt is a molten salt, and the salt ratio can be as follows:

The second proportioning: pure potassium nitrate (KNO)₃)，KNO₃The purity of (A) is more than 99.9%;

And a third ratio: 50-99.9 wt% of potassium nitrate(KNO₃) 0.1-50 wt% of sodium nitrate (NaNO)₃) And 0-5 wt% of additives and catalysts;

And a fourth ratio: 0.1-50 wt% potassium nitrate (KNO)₃) 50 to 99.9 weight percent of sodium nitrate (NaNO)₃) And 0-5 wt% of additives and catalysts.

And a fifth proportioning: 50-99.9 wt% potassium nitrate (KNO)₃) 1-50 wt% of sodium nitrate (NaNO)₃) 1-50 wt% of lithium nitrate (LiNO)₃) And 0-5.0 wt% of additives and catalysts.

And sixth proportioning: 1-50 wt% potassium (KNO)₃) 50 wt% -99.9 wt% of sodium nitrate (NaNO)₃) 1-50 wt% of lithium nitrate (LiNO)₃) And 0-5.0 wt% of additives and catalysts.

The lithium aluminosilicate nanocrystalline glass ceramic sheet can be placed in the molten salt with any one of the first proportion, the fourth proportion and the sixth proportion for ion exchange, wherein potassium nitrate in the proportion can be replaced by other salts containing potassium ions, such as potassium sulfate, potassium chloride and the like, sodium nitrate can be replaced by other salts containing sodium ions, such as sodium sulfate, sodium chloride and the like, and lithium nitrate can be replaced by other salts containing lithium ions, such as lithium sulfate, lithium chloride and the like.

In the second strengthening process, the concentration of potassium ions in the molten salt is greater than that in the first strengthening process, and the concentration of potassium ions in the first molten salt is less than that in the second molten salt; the strengthening time of the second strengthening is shorter than that of the first strengthening, i.e. the first strengthening time is longer than the second strengthening time, so that a dense ion exchange region is formed in a short distance on the surface of the lithium aluminosilicate nanocrystalline glass ceramic, and a larger compressive stress value CS1 is obtained in the region of a smaller depth of stress layer DOL 2.

Step S210: and after the second strengthening is finished, taking out the lithium aluminosilicate nanocrystalline glass ceramic from the reaction furnace and cooling.

Specifically, after the second strengthening is completed, the carrying basket carrying the lithium aluminosilicate nanocrystalline glass ceramic sheet is taken out of the reaction furnace and cooled, and the cooling process may include the following four cooling methods:

The first cooling method: rapidly cooling, namely directly taking out the bearing hanging basket from the reaction furnace without placing the bearing hanging basket in a preheating furnace, and physically cooling the lithium aluminosilicate nanocrystalline glass ceramic sheet by using a fan, wherein the temperature of the lithium aluminosilicate nanocrystalline glass ceramic sheet is rapidly reduced to room temperature;

The second cooling method: naturally cooling, taking out the bearing hanging basket bearing the lithium aluminosilicate nanocrystalline glass ceramic sheet from the reaction furnace, taking out the lithium aluminosilicate nanocrystalline glass ceramic sheet from the reaction furnace, suspending and placing the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and enabling the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, the process can avoid the waste of salts in a molten state on one hand, and can avoid the excessive salt generated on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet on the other hand, the salt dripping time is 2-10 minutes, then the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed in the preheating furnace for cooling, then the temperature is reduced to be below 100 ℃ in a natural cooling mode, then a preheating furnace door is opened, the bearing hanging basket is taken out, and the lithium aluminosilicate nanocrystalline glass ceramic sheet is allowed to stand to the room temperature;

The third cooling method: gradient cooling, namely taking the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, suspending the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and enabling molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, wherein in the process, on one hand, the molten salt can be prevented from being wasted, and on the other hand, excessive salt can be prevented from being generated on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet, the salt dropping time is 2-10 minutes, the temperature is reduced to 250-300 ℃ in a natural cooling mode, then a hanging basket bearing material is taken out of the furnace, a fan is used for physically cooling the lithium aluminosilicate nanocrystalline glass ceramic sheet, and the temperature of the lithium aluminosilicate nanocrystalline glass ceramic sheet is rapidly reduced to room temperature;

The fourth cooling method: annealing, taking the bearing hanging basket bearing the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, taking the lithium aluminosilicate nanocrystalline glass ceramic sheet out of the reaction furnace, suspending and placing the lithium aluminosilicate nanocrystalline glass ceramic sheet above the reaction furnace, and allowing molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic sheet to drop back into the reaction furnace, wherein the process can avoid waste of molten salt on one hand, and can avoid excessive salt on the surface of the cooled lithium aluminosilicate nanocrystalline glass ceramic sheet on the other hand, the salt dropping time is 2-10 minutes, and then the lithium aluminosilicate nanocrystalline glass ceramic sheet is placed into the preheating furnace to be cooled, the preheating furnace is at a constant temperature, the temperature range in the preheating furnace is 300-400 ℃, and after the molten salt dropping is completed, the temperature is reduced to below 100 ℃ in a natural cooling mode, and then opening a preheating furnace door, taking out the bearing hanging basket, and allowing the lithium aluminosilicate nanocrystalline glass ceramic sheet to stand to room temperature.

Step S211: and cleaning the lithium aluminosilicate nanocrystalline glass ceramic to remove the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic.

Specifically, the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a water bath to remove the molten salt on the surface of the lithium aluminosilicate nanocrystalline glass ceramic, and the water bath mode for dissolving the molten salt at least comprises the following 3 modes:

The first water bath mode: placing the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic in a hot water bath with the temperature range of 50-70 ℃ for soaking or spraying for 20-60 minutes;

The second water bath mode: placing the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic in a cold water bath at the temperature of 15-35 ℃ for soaking or spraying for 20-60 minutes;

The third water bath mode: firstly, the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a hot water bath with the temperature range of 50-70 ℃ for soaking or spraying for 20-60 minutes, and then the tempered fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is placed in a cold water bath with the temperature range of 15-35 ℃ for soaking or spraying for 20-60 minutes.

Step S212: and drying the lithium aluminosilicate nanocrystalline glass ceramic.

Specifically, the toughened fixing frame bearing the lithium aluminosilicate nanocrystalline glass ceramic is taken out from the water bath, and is kept stand for 20-30 minutes for water filtration until water stains are filtered out.

after the lithium aluminosilicate nanocrystalline glass ceramic material sheet with the thickness less than 3mm is subjected to strengthening treatment, the property of the lithium aluminosilicate nanocrystalline glass ceramic material sheet is obviously improved.

As shown in FIG. 3, which is a schematic diagram of stress distribution after chemical strengthening of the lithium aluminosilicate nanocrystalline glass ceramic of the present invention, the maximum surface compressive stress value CS1 is greater than 700MPa, the inflection point surface compressive stress value CS2 is greater than 100MPa, the inflection point stress layer depth DOL2 is greater than 6 μm, the maximum stress layer depth DOL1 is greater than 40 μm, and the central maximum tensile stress layer CT is less than 120 MPa. After being strengthened, the Vickers hardness reaches 800kgf/mm²The shock resistance is more than 2 joules, and the breaking strength is more than 700 MPa.

Example 1

the 2D sheet of the lithium aluminosilicate nanocrystalline glass ceramic with the dimensions of 150mm 70mm 0.7mm after grinding and polishing was strengthened by a primary strengthening method. Preheating at 450 deg.C for 60 min in KNO₃：NaNO₃And (3) carrying out primary strengthening in 93:7 molten salt, wherein the strengthening temperature is 450 ℃, the strengthening time is 250 minutes, and the cooling mode is rapid cooling. The surface stress value and the stress layer depth of the strengthened lithium aluminosilicate nanocrystalline glass ceramic sheet are as follows:

CS1(MPa)	CS2(MPa)	DOL2(μm)	DOL1(μm)
				723	112	8.1	153

the impact strength and the bending strength of the material are tested by adopting the steel ball falling and four-bar bending methods, and the test shows that the impact strength is 2.8J, the bending strength is 1180MPa, and the Vickers hardness HV is 803kgf/mm²。

Example 2

The 2D sheet of the lithium aluminosilicate nanocrystalline glass ceramic with the dimensions of 150mm 70mm 0.7mm after grinding and polishing was strengthened by a secondary strengthening method. Preheating at 300 deg.C for 60 min in KNO₃：NaNO₃Carrying out first strengthening in molten salt at the ratio of 3:2, wherein the strengthening temperature is 400 ℃, the strengthening time is 200 minutes, and the cooling mode is rapid cooling; preheating at 300 deg.C for 60 min in KNO₃Performing first strengthening in molten salt, wherein the strengthening temperature is 450 ℃, the strengthening time is 35 minutes, and the cooling mode is rapid cooling. The surface stress value and the stress layer depth of the strengthened lithium aluminosilicate nanocrystalline glass ceramic sheet are as follows:

The impact strength and the bending strength of the material are tested by adopting the steel ball falling and four-bar bending methods, and the test proves that the impact strength is 3J, the bending strength is 1095MPa, and the Vickers hardness HV is 832kgf/mm²。

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.