阅读说明：本技术 一种高致密SiC涂层的硅化石墨制备方法 (Preparation method of silicified graphite with high-density SiC coating ) 是由 薛喜利 汪洋 沈丁 董伟 薛明虎 于 2020-04-02 设计创作，主要内容包括：一种高致密SiC涂层的硅化石墨制备方法,具体制备步骤如下：在真空度为1-10<Sup>-3</Sup>Pa的高温炉内,将石墨基体置于熔融硅液中进行硅化处理,硅化处理在恒温状态下进行,硅化温度为1500-1800℃,硅化时间为1-5h,随后用机械手将处理后的石墨基体取出,继续升温至1800-2000℃排出石墨基体中残余的硅液,然后降温至沉积温度800～1200℃后,随即向炉内通入反应气体,采用化学气相沉积工艺在处理后的石墨基体表面沉积致密SiC涂层,最后降温至室温取出即可制得。本发明将硅化过程和化学气相沉积结合起来可得到完全致密的硅化石墨涂层制品,提高其性能和使用寿命。(A preparation method of siliconized graphite with a high-density SiC coating comprises the following specific preparation steps: under the vacuum degree of 1-10 ‑3 And (2) placing the graphite matrix in a Pa high-temperature furnace, carrying out silicification treatment in a constant-temperature state, carrying out the silicification at the temperature of 1500-. The invention combines the silicification process and the chemical vapor deposition to obtain the fully compact silicified graphite coating product, thereby improving the performance and prolonging the service life of the product.)

1. A preparation method of siliconized graphite with a high-density SiC coating is characterized by comprising the following specific preparation steps: under the vacuum degree of 1-10^-3And (2) placing the graphite matrix in a Pa high-temperature furnace, carrying out silicification treatment in a constant-temperature state, carrying out the silicification at the temperature of 1500-.

2. The process for preparing siliconized graphite with a highly densified SiC coating according to claim 1, characterized in that: the vacuum degree of the high-temperature furnace is 5^-3Pa。

3. The process for preparing siliconized graphite with a highly densified SiC coating according to claim 1, characterized in that: the silicification temperature is 1600 ℃, and the silicification time is 3 h.

4. The process for preparing siliconized graphite with a highly densified SiC coating according to claim 1, characterized in that: and continuously heating to 1900 ℃ to discharge residual silicon liquid in the graphite matrix.

5. The process for preparing siliconized graphite with a highly densified SiC coating according to claim 1, characterized in that: the deposition temperature was 1000 ℃.

6. The process for preparing siliconized graphite with a highly densified SiC coating according to claim 1, characterized in that: the chemical vapor deposition process conditions are that trichloromethylsilane is used as a precursor, argon is used as a diluent gas, hydrogen is used as a carrier gas, and the deposition time is 5-20 hours.

7. The process for preparing siliconized graphite with a highly densified SiC coating according to claim 6, characterized in that: the deposition time was 12 h.

8. The process for preparing siliconized graphite with a highly densified SiC coating according to claim 1, characterized in that: the purity of the silicon liquid is 99.99%, and the weight ratio of the graphite matrix to the silicon liquid is 1: 5-20.

Technical Field

The invention relates to the technical field of a preparation process of siliconized graphite, in particular to a preparation method of siliconized graphite with a high-density SiC coating.

Background

Silicified graphite as a novel engineering material embodies the complementarity of two materials of graphite and silicon carbide. It not only has the advantages of high strength, high temperature resistance, good electrical conductivity and thermal shock resistance of graphite, but also has the advantages of high hardness, oxidation resistance, corrosion resistance and the like of silicon carbide materials. The chemical property of the silicified graphite is very stable, almost resists various acid-base corrosion, can be used at the temperature of over 1200 ℃ for a long time, and is particularly suitable for being used under the harsh conditions of heavy load, high temperature, radiation, corrosion, large temperature impact and the like. Therefore, siliconized graphite is increasingly widely used in the fields of nuclear energy, environmental protection, national defense, new energy, medical instruments, high temperature, corrosion, catalysis and the like.

The thickness of the siliconized layer in the siliconized graphite material and the bonding strength of the siliconized graphite material and the substrate are key indexes for measuring the quality of the siliconized graphite product. While the traditional siliconized graphite material has certain micro pores left on the surface after removing the surplus silicon, so that the specific surface area of the traditional siliconized graphite material is greatly increased, meanwhile, the micro pores can adsorb H2O, O2 and other gases, the oxide gas has serious corrosivity to SiC at high temperature, and once the siliconized graphite layer fails, the graphite substrate can be exposed in a high-temperature oxidizing atmosphere to be rapidly oxidized. Therefore, the invention combines the expensive infiltration reaction method and the chemical vapor deposition method, and a compact SiC coating is deposited on the surface of the silicon-containing material after the silicification reaction is finished, so as to achieve the high-efficiency protection effect.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the preparation method of the high-density SiC coating siliconized graphite, which can deposit a layer of compact SiC coating on the surface of a graphite matrix to achieve the high-efficiency protection effect.

The invention relates to a preparation method of siliconized graphite with a high-density SiC coating, which is characterized by comprising the following specific preparation steps: under the vacuum degree of 1-10^-3Placing a graphite substrate in a molten silicon liquid for silicification treatment in a Pa high-temperature furnace, wherein the silicification treatment is carried out in a constant-temperature state, the silicification temperature is 1500-And C, cooling the coating to room temperature and taking out the coating to obtain the coating. .

In the technical scheme of the preparation method of the siliconized graphite with the high-density SiC coating, the further preferable technical scheme is characterized in that:

1. the vacuum degree of the high-temperature furnace is 5^-3Pa；

2. The silicification temperature is 1600 ℃, and the silicification time is 3 h;

3. continuously heating to 1900 ℃ and discharging residual silicon liquid in the graphite matrix;

4. the deposition temperature is 1000 ℃;

5. the chemical vapor deposition process conditions are that trichloromethylsilane is used as a precursor, argon is used as a diluent gas, hydrogen is used as a carrier gas, and the deposition time is 5-20 h;

6. the deposition time is 12 h;

7. the purity of the silicon liquid is 99.99%, and the weight ratio of the graphite matrix to the silicon liquid is 1: 5-20.

Compared with the prior art, the invention has the beneficial effects that:

1. the combination of the siliconizing process and the chemical vapor deposition can obtain a fully dense siliconized graphite coating product, improve the performance and prolong the service life of the product.

2. The invention does not need to take out the product after the silicification treatment, and carries out the chemical vapor deposition process after the temperature is reduced to the deposition temperature, thereby greatly saving the preparation time.

Detailed Description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.