Graphite base with protective coating layer and preparation method thereof

Abstract

The invention provides a graphite base with a protective coating layer and a preparation method thereof. The invention prepares a silicon carbide coating layer on the surface of the porous graphite base through combining the in-situ chemical gas-phase reaction permeation and the chemical gas-phase deposition two-step method. The preparation method is carried out according to the following steps: placing the a base body of the graphite base in a reaction chamber, introducing SiCl4 gas and H2 gas into the reaction chamber according to the volume ratio that SiCl4 / H2 equals to 1 / 5 to 50 under thecondition of the reaction chamber temperature between 1300 and 1600 DEG C and the vacuum between 200 and 500 Pa, wherein the hydrogen flow rate is between 200 and 1000 ml / min, the gas introduction time is between 0.5 and 2 hours, and a primary SiC coating layer is permeated on the base body of the graphite base through the in-situ gas-phase reaction; and then b, introducing CH3SiCl3 gas and H2 gas into the reaction chamber according to the volume ratio that CH3SiCl3 / H2 equals to 1 / 5 to 100, controlling the hydrogen flow rate to be in a range between 200 and 1000 ml / m and the gas introduction time between 1 and 50 hours, and depositing a secondary SiC coating layer outside the surface of the primary SiC coating layer after schizolysis.

Description

Technical field: [0001] The invention relates to the technical field of high-purity graphite bases, and further relates to a graphite base with a SiC (silicon carbide) protective coating and a preparation method thereof. Background technique: [0002] The research and application of GaN materials is the frontier and hotspot of global semiconductor research at present. It is a new type of semiconductor material for the development of microelectronic devices and optoelectronic devices. For the preparation of single crystal GaN materials and the growth of silicon epitaxial single crystals, vapor phase epitaxy is generally used ( That is, chemical vapor deposition (CVD) method. In the process of preparing GaN single crystal and silicon epitaxial single crystal materials, it is necessary to ensure that the reaction environment is highly clean. At present, in the process of epitaxially growing single crystal materials, the reaction bases / crucibles used are all graphite materials....

AI Technical Summary

Problems solved by technology

Solve some insurmountable problems in the preparation method of graphite base: 1. Density, SiC materials prepared by traditional processes are difficult to be completely dense

2. Surface flatness. Since the graphite base used for single crystal growth requires very high surface flatness, the original flatness of the base must be maintained after the coating is prepared, that is, the coating surface must be uniform, and the traditional preparation process is difficult. do it

3. Fully wrapped, the graphite base as a whole must be in a corrosive, 1000-1800°C working environment, the entire surface must be fully wrapped with a coating, and the traditional preparation process has support point defects

4. Bonding strength: Due to the difference in expansion coefficient between graphite substrate and SiC, SiC coatings prepared by traditional processes tend to crack, resulting in coating failure

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