阅读说明：本技术 一种二硅酸锂晶须的制备方法 (Preparation method of lithium disilicate whisker ) 是由 张亚明 徐建刚 李永锋 张云光 李仃 任卫 贾艳敏 于 2019-11-14 设计创作，主要内容包括：一种二硅酸锂晶须的制备方法,将KCl和K<Sub>2</Sub>SO<Sub>4</Sub>均匀混合,得到熔盐混合料,将LiCl和SiO<Sub>2</Sub>纳米粉均匀混合,得到反应物混合料,将熔盐混合料和反应物混合料均匀混合后在400℃～600℃下进行热处理,冷却后进行清洗、过筛,得到二硅酸锂晶须。本发明操作简单,耗能低,晶体提取率高,尺寸型貌可控,得到的二硅酸锂晶须可作为一种陶瓷增强相使用,可广泛应用于玻璃、陶瓷等无机材料和高分子基体中。(A process for preparing lithium disilicate crystal whisker includes such steps as mixing KCl with K 2 SO 4 Uniformly mixing to obtain molten salt mixture, and mixing LiCl and SiO 2 And uniformly mixing the nano powder to obtain a reactant mixture, uniformly mixing the fused salt mixture and the reactant mixture, performing heat treatment at 400-600 ℃, cooling, cleaning, and sieving to obtain the lithium disilicate whisker. The invention has simple operation, low energy consumption, high crystal extraction rate and controllable size and appearance, and the obtained lithium disilicate crystal whisker can be used as a ceramic reinforcing phase and can be widely applied to inorganic materials such as glass, ceramics and the like and polymer matrixes.)

1. A process for preparing lithium disilicate crystal whisker includes such steps as mixing KCl with K₂SO₄Uniformly mixing to obtain molten salt mixture, and mixing LiCl and SiO₂And uniformly mixing the nano powder to obtain a reactant mixture, uniformly mixing the fused salt mixture and the reactant mixture, performing heat treatment at 400-600 ℃, cooling, cleaning, and sieving to obtain the lithium disilicate whisker.

2. The method of claim 1, wherein KCl and K are selected from the group consisting of₂SO₄The mass ratio of (A) to (B) is 1: 2-1: 5.

3. The method of claim 1, wherein LiCl and SiO are used to prepare the lithium disilicate whisker₂The mass ratio of (A) to (B) is 2: 1-5: 1.

4. The method for preparing lithium disilicate whiskers according to claim 1, wherein a mass ratio of the molten salt mixture to the reactant mixture is 1: 10-1: 20.

5. The method for preparing lithium disilicate whiskers according to claim 1, wherein the time of the heat treatment is 2h to 8 h.

6. The method of claim 5, wherein the temperature is raised from room temperature to 400 ℃ to 600 ℃ at a temperature raising rate of 2 ℃/min to 10 ℃/min.

7. The method of claim 1, wherein KCl and K are selected from the group consisting of₂SO₄Homogeneous mixing, LiCl and SiO₂The uniform mixing of the nanometer powder and the uniform mixing of the molten salt mixture and the reactant mixture are carried out by dry mixing of a polyethylene tank and zirconia balls, the ball-material ratio is 5: 1-10: 1, and the rotating speed of the mixed materials is less than 200 r/min.

8. The method for preparing lithium disilicate whiskers according to claim 1, wherein the molten salt mixture and the reactant mixture are uniformly mixed and then put into an alumina crucible with a purity of more than 99.9%, followed by heat treatment in a muffle furnace.

9. The method for preparing lithium disilicate whiskers according to claim 1, wherein the specific processes of cleaning and sieving after cooling are as follows: and (3) cooling the heat-treated fused salt in a stainless steel plate by air, then cleaning the fused salt for multiple times by using hot water with the temperature of more than 80 ℃, drying the fused salt, screening the fused salt by using a screen with 500-1000 meshes, and obtaining powder which is lithium disilicate whisker after screening.

Technical Field

The invention belongs to the technical field of inorganic nano powder preparation, and particularly relates to a preparation method of lithium disilicate whiskers.

Background

In the field of strengthening and toughening of engineering materials, strengthening and toughening treatment of materials by adopting a strengthening phase with a certain length-diameter ratio is a conventional strengthening means. The commonly related materials comprise carbon fiber, mullite fiber, steel fiber and the like, and the second phase material with higher single-phase modulus is mainly added into a brittle matrix such as structural ceramic, microcrystalline glass or some high polymer material matrixes needing higher strength in a mechanical mixing mode, when a structural body is broken, the propagation process of cracks can have strengthening effects such as blocking, crack deflection, whisker/fiber extraction and the like of the second phase material with a certain length-diameter ratio, and further a certain strengthening and toughening effect is achieved on the material matrixes.

Lithium disilicate crystals, which are anisotropically grown layered crystals, are of increasing interest to researchers as a novel reinforcing phase. The patent CN201811622254.1 discloses a method for toughening lithium disilicate glass ceramics by seed type, and relates to a method for preparing lithium disilicate rod-shaped crystals by using a powder sintering method, wherein Li is used₂CO₃And SiO₂Sintering and purifying the raw material powder to obtain the lithium disilicate rod-shaped crystal with a shaped appearance. Patent CN110079857A discloses a method for preparing lithium disilicate rod-shaped crystals by a hydrothermal method, which adopts a two-step method, wherein the method comprises the steps of raw material reaction and heat treatment to obtain lithium disilicate rod-shaped crystals.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the preparation method of the lithium disilicate crystal whisker, which has the advantages of low heat treatment temperature, easily obtained raw materials, relatively simple preparation process, higher purity of the obtained lithium disilicate crystal whisker, controllable crystal morphology and better application foundation.

In order to achieve the purpose, the invention adopts the following technical scheme:

preparation method of lithium disilicate whiskerKCl and K₂SO₄Uniformly mixing to obtain molten salt mixture, and mixing LiCl and SiO₂And uniformly mixing the nano powder to obtain a reactant mixture, uniformly mixing the fused salt mixture and the reactant mixture, performing heat treatment at 400-600 ℃, cooling, cleaning, and sieving to obtain the lithium disilicate whisker.

A further improvement of the invention is that KCl and K₂SO₄The mass ratio of (A) to (B) is 1: 2-1: 5.

A further development of the invention consists in that LiCl and SiO₂The mass ratio of (A) to (B) is 2: 1-5: 1.

The invention further improves that the mass ratio of the molten salt mixture to the reactant mixture is 1: 10-1: 20.

The invention is further improved in that the time of the heat treatment is 2-8 h.

The invention has the further improvement that the temperature is increased from room temperature to 400-600 ℃ at the temperature increase rate of 2-10 ℃/min.

A further improvement of the invention is that KCl and K₂SO₄Homogeneous mixing, LiCl and SiO₂The uniform mixing of the nanometer powder and the uniform mixing of the molten salt mixture and the reactant mixture are carried out by dry mixing of a polyethylene tank and zirconia balls, the ball-material ratio is 5: 1-10: 1, and the rotating speed of the mixed materials is less than 200 r/min.

The further improvement of the invention is that the molten salt mixture and the reactant mixture are uniformly mixed and then put into an alumina crucible with the purity of more than 99.9 percent, and then heat treatment is carried out in a muffle furnace.

The further improvement of the invention is that the specific processes of cleaning and sieving after cooling are as follows: and (3) cooling the heat-treated fused salt in a stainless steel plate by air, then cleaning the fused salt for multiple times by using hot water with the temperature of more than 80 ℃, drying the fused salt, screening the fused salt by using a screen with 500-1000 meshes, and obtaining powder which is lithium disilicate whisker after screening. Compared with the prior art, the invention has the beneficial effects that: the method adopted by the invention is a molten salt method, and LiCl and SiO are used₂As reaction matrix, KCl and K₂SO₄Is a composite molten salt, and at relatively low temperature,the reaction is carried out by utilizing the diffusion effect of the reaction raw materials in the liquid molten salt to obtain the whisker-shaped high-purity lithium disilicate crystal, which can be used as a ceramic reinforcing phase and can be widely applied to inorganic materials such as glass, ceramics and the like and polymer matrixes. The invention has the following advantages:

1. the raw materials are mixed into dry mixture, and the method is particularly suitable for mass preparation and production.

2. The preparation process has lower temperature and lower energy consumption.

3. The preparation process and the crystal form appearance are controllable, the powder purity is higher, and the yield is high.

Drawings

FIG. 1 is a SEM photograph of the structure of the material obtained in example 3 of the present invention.

FIG. 2 is an XRD pattern of the material obtained in example 3 of the present invention.

Detailed Description

The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.

The invention provides a preparation method of lithium disilicate crystal whisker, which is prepared by mixing KCl and K₂SO₄Mixing uniformly to obtain molten salt mixture, and mixing LiCl and SiO₂And uniformly mixing the nano powder to obtain a reactant mixture, uniformly mixing the two obtained mixtures according to a ratio, filling the mixed powder into an alumina crucible, carrying out low-temperature heat treatment in a muffle furnace, pouring the molten salt subjected to heat treatment into a stainless steel plate for air cooling, cleaning the obtained block for multiple times by using hot water with the temperature of more than 80 ℃ after cooling, cleaning and drying, screening by using a 500-1000-mesh screen, and obtaining the powder after screening, namely the high-purity lithium disilicate whisker.

In the present invention, KCl and K₂SO₄The main body of the molten salt is LiCl and SiO in a mass ratio of 1: 2-1: 5₂The mass ratio of the main reactant is 2: 1-5: 1. The mixing mass ratio of the molten salt mixture to the reactant mixture is 1: 10-1: 20.

In the present invention, KCl and K₂SO₄Homogeneous mixing, LiCl and SiO₂Nano powder is uniformThe mixing and the uniform mixing of the molten salt mixture and the reactant mixture are carried out by dry mixing of a polyethylene tank and zirconia balls, the ball-to-material ratio is 5: 1-10: 1, and the rotating speed of the mixing is less than 200 r/min.

In the invention, the purity of the alumina crucible is more than 99.9 percent, the heat treatment temperature of the mixture in the muffle furnace is 400-600 ℃, the heating rate is 2-10 ℃/min, and the heat treatment time is 2-8 h.