High-performance silicon carbide coating embedding process

Abstract

The invention discloses a high-performance silicon carbide coating embedding process, and relates to the technical field of static pressure graphite coating materials. The preparation method comprises the following steps: firstly, weighing SiC powder, Si powder and carbon powder according to a specific mass ratio, and carrying out ball milling and mixing to prepare embedding powder; the preparation method comprises the following steps: embedding a graphite matrix into embedding powder, and carrying out argon protection and temperature programming sintering to prepare a SiC coating modified graphite matrix; then preparing dendritic polysilazane steeping liquor containing azobenzene groups, putting the modified matrix into a vacuum steeping tank, carrying out ultraviolet irradiation assisted vacuum steeping and gradient drying, and then carrying out temperature programming curing, so as to obtain the composite coating modified graphite material. According to the process, the problems that a traditional embedding method has many coating defects and the mechanical property of a matrix is reduced are solved, through deep penetration repairing of photosensitive dendritic polysilazane, the coating density and the interface bonding strength are improved, and the obtained material has excellent mechanical and thermal properties and structural stability and meets the requirement of high-end working conditions.

Description

Technical Field

[0001] This invention relates to the field of hydrostatic graphite coating materials technology, specifically a high-performance silicon carbide coating embedding process. Background Technology

[0002] Graphite materials, due to their low coefficient of thermal expansion, high thermal and electrical conductivity, and excellent high-temperature stability, are widely used in high-end manufacturing fields such as semiconductor thermal fields, photovoltaic equipment, and aerospace. However, graphite is prone to oxidation and ablation in high-temperature oxygen-containing environments, and its surface strength and wear resistance are insufficient. Therefore, a SiC coating is typically prepared on its surface for protection. The embedding method, due to its simple process, low cost, and good adhesion between the coating and the substrate, has become a commonly used technical route for the large-scale preparation of SiC coatings.

[0003] However, SiC coatings prepared by traditional embedding methods have significant technical drawbacks: micropores and cracks easily remain inside the coating, resulting in low density; the interfacial bonding strength between the coating and the substrate is insufficient, leading to cracking and detachment under high-temperature conditions; simple embedding and sintering cannot achieve closed-loop repair of defects, thus limiting the material's mechanical properties, oxidation resistance, and structural stability. Furthermore, conventional impregnation modification processes suffer from poor penetration and insufficient curing, failing to deeply fill the micropores in the coating and enhance the interface, making it difficult to meet the long-term reliable service requirements of graphite-based composite materials in high-end equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a high-performance silicon carbide coating embedding process to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A high-performance silicon carbide coating embedding process includes the following preparation steps: S1. The graphite matrix is ​​completely embedded in a corundum crucible containing embedding powder, with an embedding layer thickness of 9~11mm. The crucible is placed in a sintering furnace, protected by argon gas, and heated according to the program. Then, it is cooled to room temperature with the furnace. The sample is taken out and the residual embedding powder on the surface is blown off with compressed air to obtain a SiC-coated modified graphite matrix. S2. Mix the polymer monomer, isopropanol chloroplatinic acid solution, and p-benzoquinone at a mass ratio of 1:2.4%~2.6%:0.55%~0.6%. After mixing, stir and react at 80~85℃ for 1~2 hours. After the reaction is complete, dissolve the polymer in diethyl ether and precipitate it in acetonitrile. Repeat this process three times and separate the liquids. Collect the lower liquid and evaporate the solvent to obtain dendritic polysilazane. Add the dendritic polysilazane to toluene at 3.4~4.1 times its mass, and then add 0.45%~0.55% benzoyl peroxide at its mass. Stir until homogeneous to prepare an impregnation solution for later use. S3. Place the SiC-coated modified graphite substrate into a vacuum impregnation tank, evacuate to -0.093~-0.097MPa and maintain for 28~32min; inject impregnation liquid until the substrate is completely submerged, turn on ultraviolet light at 365nm with an intensity of 9~11mW / cm², and impregnate in vacuum for 1.8~2.2h. Turn off the ultraviolet light, slowly release to normal pressure, and continue impregnation for 0.8~1.2h. Remove the impregnated substrate, air dry naturally for 22~26h, then dry at 58~62℃ for 1.8~2.2h and 78~82℃ for 1.8~2.2h to remove residual solvent. Place the pre-dried sample into a programmed temperature oven and cure by gradient temperature increase. Cool naturally to room temperature to obtain the composite-coated modified graphite material.

[0006] Further, preferably, the embedding powder in S1 includes the following preparation steps: weigh 10-20 μm SiC powder, 5-10 μm Si powder and 1-5 μm carbon powder in a mass ratio of 70:19~21:9~11, and ball mill and mix them evenly to obtain the embedding powder.

[0007] Further, preferably, the programmed temperature rise conditions in S1 are as follows: Stage 1: 4.5~5.5℃ / min, rise to 490~510℃, hold for 28~32min; Stage 2: 2.8~3.2℃ / min, rise to 1440~1460℃, hold for 1.8~2.2h.

[0008] Further, preferably, the programmed temperature rise conditions in S3 are as follows: Stage 1: 1.8~2.2℃ / min, rise to 118~122℃, hold for 0.8~1.2h; Stage 2: 1.8~2.2℃ / min, rise to 158~162℃, hold for 1.8~2.2h; Stage 3: 0.9~1.1℃ / min, rise to 178~182℃, hold for 2.8~3.2h.

[0009] Further, preferably, the polymeric monomer comprises the following preparation steps: adding dimethylhydrochlorosilane to toluene at a mass ratio of 1:1.5~1.8 to prepare a dimethylhydrochlorosilane solution for later use; adding 4-amino-4'-methacrylate-based azobenzene, triethylamine, and hydroquinone to toluene at a mass ratio of 1:1.4~1.6:0.01%~0.05%:1.3~1.5, stirring evenly at a temperature of -5~0℃, and adding the dimethylhydrochlorosilane solution dropwise. After the addition is complete, reacting at a temperature of 25~35℃ for 4~5 hours. After the reaction is complete, allowing the precipitate to stand and filtering the precipitate, then adding 0.05%~0.1% of hydroquinone by mass of 4-amino-4'-methacrylate-based azobenzene to the filtrate, followed by rotary evaporation and silica gel column chromatography to obtain the polymeric monomer.

[0010] Further, preferably, the mass ratio between the 4-amino-4'-methacrylate-based azobenzene and dimethylhydrochlorosilane is 1.35~1.45:1.

[0011] Further, preferably, the eluent in the silica gel column chromatography is petroleum ether: ethyl acetate = 15:1, by volume.

[0012] A composite coating modified graphite material is prepared by any one of the high-performance silicon carbide coating embedding processes described above.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are: This technical solution specifically addresses the core pain points of the embedding method for preparing SiC coatings, effectively compensating for the shortcomings of traditional embedding processes. In the embedding method for SiC coating preparation, silicon powder is prone to sintering into lumps and melting into the graphite matrix, easily generating thermal stress, leading to a decrease in matrix strength and mechanical properties, and easy formation of surface defects. This application uses dendritic polysilazane to prepare the impregnation solution, and performs penetration repair on the SiC coating through vacuum impregnation. Its branched structure gives it excellent solubility and low viscosity in organic solvents, allowing it to quickly penetrate to the micropores and defects in the SiC coating, achieving precise sealing of coating defects, significantly reducing coating porosity, and avoiding secondary damage to the graphite matrix during the repair process. This effectively alleviates thermal stress in the matrix and ensures that the original strength and mechanical properties of the graphite matrix are not compromised.

[0014] This technical solution enhances the impregnation repair effect and coating performance by incorporating an azo compound into dendritic polysilazane and leveraging the photosensitive and reversible cis-trans isomerism of the azobenzene structure. Under ultraviolet light, the azobenzene transforms from a trans isomer to a cis isomer, causing a reversible change in the dipole moment and molecular volume of the dendritic polysilazane molecule. This allows its polarity to match the microporous surface characteristics of the SiC coating, significantly improving penetration depth and wettability, ensuring that the dendritic polysilazane fully fills the internal defects of the coating. After light exposure, the azobenzene reverts to the trans isomer, enabling the dendritic polysilazane to form a stable structure within the coating pores, further enhancing the bonding strength between the SiC coating and the graphite matrix. Ultimately, this results in a composite coating that combines excellent density, mechanical properties, and structural stability, extending the material's service life. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1:

[0017] S1. Dimethylhydrochlorosilane was added to toluene at a mass ratio of 1:1.5 to prepare a dimethylhydrochlorosilane solution for later use. 4-Amino-4'-methacrylate-based azobenzene, triethylamine, and hydroquinone were added to toluene at a mass ratio of 1:1.4:0.01%:1.3. The mixture was stirred thoroughly at -5°C, and the dimethylhydrochlorosilane solution was added dropwise. After the addition was complete, the reaction was carried out at 25°C for 4 hours. After the reaction was complete, the mixture was allowed to stand to precipitate, and the precipitate was filtered. 0.05% (by mass) of hydroquinone (4-amino-4'-methacrylate-based azobenzene) was added to the filtrate. The mixture was then subjected to rotary evaporation and silica gel column chromatography to separate the monomers. The mass ratio of 4-amino-4'-methacrylate-based azobenzene to dimethylhydrochlorosilane was 1.35:1. The eluent used in the silica gel column chromatography was petroleum ether:ethyl acetate = 15:1 (volume ratio). S2. The polymer monomer, isopropanol chloroplatinic acid solution and p-benzoquinone were mixed in a mass ratio of 1:2.4%:0.55%. After mixing, the mixture was stirred and reacted at 80°C for 1 hour. After the reaction was completed, the mixture was dissolved in ether and precipitated with acetonitrile. The reaction was repeated three times and the mixture was separated. The lower liquid was collected and the solvent was evaporated to obtain dendritic polysilazane. S3. Weigh 10μm SiC powder, 5μm Si powder, and 1μm carbon powder at a mass ratio of 70:19:9, and ball mill them together to obtain an embedded powder. Completely embed the graphite matrix into an alumina crucible containing the embedded powder, with an embedded layer thickness of 9mm. Place the crucible in a sintering furnace, purge it with argon gas, and heat it according to the program: Stage 1: 4.5℃ / min, heat to 490℃, hold for 28min; Stage 2: 2.8℃ / min, heat to 1440℃, hold for 1.8h, then cool it to room temperature with the furnace. Take out the sample and blow off the residual embedded powder on the surface with compressed air to obtain a SiC-coated modified graphite matrix. S4. Add dendritic polysilazane to toluene at 3.4 times its mass, then add 0.45% benzoyl peroxide (by mass of dendritic polysilazane), stir well to prepare an impregnation solution, and set aside. Place the SiC-coated modified graphite substrate into a vacuum impregnation tank, evacuate to -0.097 MPa and maintain for 28 min. Pour in the impregnation solution until the substrate is completely submerged, turn on ultraviolet light at 365 nm with an intensity of 9 mW / cm², vacuum impregnate for 1.8 h, turn off the ultraviolet light, slowly release to atmospheric pressure, and continue impregnation for 0 h. After 8 hours, the impregnated substrate was removed and allowed to air dry naturally for 22 hours. Then, it was dried at 58℃ for 1.8 hours and 78℃ for 1.8 hours to remove residual solvent. The pre-dried sample was then placed in a programmed temperature oven and cured by gradient temperature increase: Stage 1: 1.8℃ / min, heating to 118℃ and holding for 0.8 hours; Stage 2: 1.8℃ / min, heating to 158℃ and holding for 1.8 hours; Stage 3: 0.9℃ / min, heating to 178℃ and holding for 2.8 hours. The sample was then allowed to cool naturally to room temperature to obtain the composite coated modified graphite material.

[0018] Example 2:

[0019] S1. Dimethylhydrochlorosilane was added to toluene at a mass ratio of 1:1.65 to prepare a dimethylhydrochlorosilane solution for later use. 4-Amino-4'-methacrylate-based azobenzene, triethylamine, and hydroquinone were added to toluene at a mass ratio of 1:1.5:0.03%:1.4. The mixture was stirred thoroughly at -2.5℃, and the dimethylhydrochlorosilane solution was added dropwise. After the addition was complete, the reaction was carried out at 30℃ for 4.5 hours. After the reaction was complete, the mixture was allowed to stand to precipitate, and the precipitate was filtered. 0.075% (by mass) of hydroquinone (4-amino-4'-methacrylate-based azobenzene) was added to the filtrate. The mixture was then subjected to rotary evaporation and silica gel column chromatography to separate the monomers. The mass ratio of 4-amino-4'-methacrylate-based azobenzene to dimethylhydrochlorosilane was 1.4:1. The eluent used in the silica gel column chromatography was petroleum ether:ethyl acetate = 15:1 (volume ratio). S2. The polymer monomer, isopropanol chloroplatinic acid solution and p-benzoquinone were mixed in a mass ratio of 1:2.5%:0.575%. After mixing, the mixture was stirred and reacted at 82.5℃ for 1.5h. After the reaction was completed, the mixture was dissolved in ether and precipitated with acetonitrile. The reaction was repeated three times. The mixture was separated, the lower liquid was collected, and the solvent was evaporated to obtain dendritic polysilazane. S3. Weigh 15μm SiC powder, 7.5μm Si powder, and 3μm carbon powder in a mass ratio of 70:20:10, and ball mill them together to obtain an embedded powder. Completely embed the graphite matrix into an alumina crucible containing the embedded powder, with an embedded layer thickness of 10mm. Place the crucible in a sintering furnace, purge with argon gas, and heat according to the program: Stage 1: 5.0℃ / min, heat to 500℃, hold for 30min; Stage 2: 3.0℃ / min, heat to 1450℃, hold for 2.0h, then cool with the furnace to room temperature. Remove the sample and blow off the residual embedded powder on the surface with compressed air to obtain a SiC-coated modified graphite matrix. S4. Add dendritic polysilazane to toluene at 3.75 times its mass, then add 0.5% benzoyl peroxide (by mass of dendritic polysilazane), and stir until homogeneous to prepare an impregnation solution. Place the SiC-coated modified graphite substrate into a vacuum impregnation tank, evacuate to -0.095 MPa and maintain for 30 min. Pour in the impregnation solution until the substrate is completely submerged, turn on ultraviolet light at 365 nm and 10 mW / cm², and impregnate under vacuum for 2.0 h. Turn off the ultraviolet light, slowly release to atmospheric pressure, and continue impregnation for 1 hour. After 0h, the impregnated substrate was removed and allowed to air dry naturally for 24h, followed by drying at 60℃ for 2.0h and 80℃ for 2.0h to remove residual solvent. The pre-dried sample was then placed in a programmed temperature oven and cured by gradient temperature increase: Stage 1: 2.0℃ / min, heating to 120℃ and holding for 1.0h; Stage 2: 2.0℃ / min, heating to 160℃ and holding for 2.0h; Stage 3: 1.0℃ / min, heating to 180℃ and holding for 3.0h. The sample was then allowed to cool naturally to room temperature to obtain the composite coated modified graphite material.

[0020] Example 3:

[0021] S1. Dimethylhydrochlorosilane was added to toluene at a mass ratio of 1:1.8 to prepare a dimethylhydrochlorosilane solution for later use. 4-Amino-4'-methacrylate-based azobenzene, triethylamine, and hydroquinone were added to toluene at a mass ratio of 1:1.6:0.05%:1.5. The mixture was stirred thoroughly at 0°C, and the dimethylhydrochlorosilane solution was added dropwise. After the addition was complete, the mixture was reacted at 35°C for 5 hours. After the reaction was complete, the mixture was allowed to stand to precipitate, and the precipitate was filtered. 0.1% (by mass) of hydroquinone (4-amino-4'-methacrylate-based azobenzene) was added to the filtrate. The mixture was then subjected to rotary evaporation and silica gel column chromatography to separate the monomers. The mass ratio of 4-amino-4'-methacrylate-based azobenzene to dimethylhydrochlorosilane was 1.45:1. The eluent used in the silica gel column chromatography was petroleum ether:ethyl acetate = 15:1 (volume ratio). S2. The polymer monomer, isopropanol chloroplatinic acid solution and p-benzoquinone were mixed in a mass ratio of 1:2.6%:0.6%. After mixing, the mixture was stirred and reacted at 85°C for 2 hours. After the reaction was completed, the mixture was dissolved in ether and precipitated with acetonitrile. The reaction was repeated three times and the mixture was separated. The lower liquid was collected and the solvent was evaporated to obtain dendritic polysilazane. S3. Weigh 20μm SiC powder, 10μm Si powder, and 5μm carbon powder at a mass ratio of 70:21:11, and ball mill them together to obtain an embedded powder. Completely embed the graphite matrix into an alumina crucible containing the embedded powder, with an embedded layer thickness of 11mm. Place the crucible in a sintering furnace, purge it with argon gas, and heat it according to the program: Stage 1: 5.5℃ / min, heat to 510℃, hold for 32min; Stage 2: 3.2℃ / min, heat to 1460℃, hold for 2.2h, then cool it to room temperature with the furnace. Take out the sample and blow off the residual embedded powder on the surface with compressed air to obtain a SiC-coated modified graphite matrix. S4. Add dendritic polysilazane to toluene at 4.1 times its mass, then add 0.55% benzoyl peroxide (by mass of dendritic polysilazane), and stir until homogeneous to prepare an impregnation solution. Place the SiC-coated modified graphite substrate into a vacuum impregnation tank, evacuate to -0.093 MPa and maintain for 32 min. Pour in the impregnation solution until the substrate is completely submerged, turn on ultraviolet light at 365 nm (11 mW / cm²), and impregnate under vacuum for 2.2 h. Turn off the ultraviolet light, slowly release to atmospheric pressure, and continue impregnation for 1 hour. After 2 hours of drying, the impregnated substrate was removed and allowed to air dry naturally for 26 hours. Then, it was dried at 62℃ for 2.2 hours and 82℃ for 2.2 hours to remove residual solvent. The pre-dried sample was then placed in a programmed temperature oven and cured by gradient temperature increase: Stage 1: 2.2℃ / min, heating to 122℃ and holding for 1.2 hours; Stage 2: 2.2℃ / min, heating to 162℃ and holding for 2.2 hours; Stage 3: 1.1℃ / min, heating to 182℃ and holding for 3.2 hours. The sample was then allowed to cool naturally to room temperature to obtain the composite coated modified graphite material.

[0022] Example 4:

[0023] The only difference from Example 2 is step S4: commercially available organopolysilazane (OPSZ) is used as the impregnation solution.

[0024] Example 5:

[0025] The difference from Example 2 is that step S4 is not performed.

[0026] Performance testing: The composite coating modified graphite materials prepared in Examples 1 to 5 above were tested according to the following standards, and the test results are shown in Table 1 below; Table 1 Performance Test Results Testing standards project unit Example 1 Example 2 Example 3 Example 4 Example 5 GB / T 24528-2009 density g / cm³ 1.91 1.94 1.92 1.87 1.82 ASTM E1461-13 thermal conductivity W / (m·K) 124 128 125 112 101 GB / T 24525-2009 resistivity μΩ·m 8.2 8.5 8.8 10.5 12.2 GB / T 3074.4-2016 coefficient of thermal expansion <![CDATA[10 -6 / K]]> 4.5 4.2 4.8 4.9 5.3 JB / T 8133.4-2013 Shore hardness HSD 61 67 63 54 47 JB / T 8133.7-2013 Flexural strength MPa 40 43 41 35 28 JB / T 1333.8-2013 compressive strength MPa 92 105 98 81 70 GB / T 3074.2-2008 elastic modulus GPa 12.6 13.8 13.1 11.2 9.7 GB / T 1429-2022 Ash ppm 4.1 3.2 3.8 6.7 8.5 ISO / TS 15338 Total metal ion content ppbw 0.8 0.5 0.7 1.6 2.3 Examples 1-3 all exhibited excellent overall performance, demonstrating outstanding performance in terms of density, thermal conductivity, mechanical strength, and purity. Among them, Example 2 showed the most balanced and superior performance, with a density of 1.94 g / cm³, a thermal conductivity as high as 128 W / (m·K), flexural strength and compressive strength reaching 43 MPa and 105 MPa respectively, an elastic modulus of 13.8 GPa, and a low coefficient of thermal expansion of 4.2 × 10⁻⁶. -6 With a density of / K and an ash content of only 3.2ppm and a total metal ion content of 0.5ppbw, it not only possesses excellent structural compactness, thermal conductivity, and high-temperature mechanical load-bearing capacity, but also has photovoltaic-grade ultra-high material purity. This fully demonstrates the advantages of the embedding-impregnation synergistic process in this technical solution, as well as the efficient repair effect of photosensitive dendritic polysilazane on defects in SiC coatings.

[0027] The overall performance of Example 4 is significantly lower than that of Example 2. The thermal conductivity drops to 112 W / (m·K), the flexural strength and compressive strength decrease to 35 MPa and 81 MPa, respectively, the elastic modulus is only 11.2 GPa, and the coefficient of thermal expansion increases to 4.9 × 10⁻⁶. -6 / K, ash content and total metal ion content also increased significantly (reaching 6.7 ppm and 1.6 ppbw, respectively). The core reason is that Example 4 did not use the dendritic polysilazane prepared in this invention, but instead used a commercially available ordinary organopolysilazane as the impregnation liquid. It lacks the light-controlled polarity switching function of the azophenyl group and the high permeability of the dendritic branched structure, and cannot achieve deep filling and sealing of the micropores in the SiC coating. The interfacial bonding strength between the coating and the substrate is insufficient, which leads to a significant decline in various performance indicators.

[0028] Example 5 exhibited the worst performance among all examples, with a thermal conductivity of only 101 W / (m·K), flexural and compressive strengths of only 28 MPa and 70 MPa respectively, an elastic modulus of only 9.7 GPa, and a coefficient of thermal expansion as high as 5.3 × 10⁻⁶. -6 / K, the ash content and total metal ion content both reached the highest of all groups (8.5ppm and 2.3ppbw, respectively), and the overall performance was significantly different from that of Example 2. This is because Example 5 did not perform the vacuum impregnation and polymer filling treatment in step S4, and only prepared the SiC coating by the embedding method. It failed to make up for the defects in the embedding process itself. The thermal stress generated by silicon powder sintering and agglomeration was not relieved, and the micropores and cracks inside the coating were not sealed. As a result, the material density was low, the interfacial bonding was weak, and the mechanical properties, thermal conductivity, thermal stability and purity were all seriously affected, and the synergistic reinforcing effect of the composite coating could not be exerted.

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-performance silicon carbide coating embedding process, characterized in that, The preparation steps include the following: S1. The graphite matrix is ​​completely embedded in a corundum crucible containing embedding powder, with an embedding layer thickness of 9~11mm. The crucible is placed in a sintering furnace, protected by argon gas, and heated according to the program. Then, it is cooled to room temperature with the furnace. The sample is taken out and the residual embedding powder on the surface is blown off with compressed air to obtain a SiC-coated modified graphite matrix. S2. Mix the polymer monomer, isopropanol chloroplatinic acid solution, and p-benzoquinone at a mass ratio of 1:2.4%~2.6%:0.55%~0.6%. After mixing, stir and react at 80~85℃ for 1~2 hours. After the reaction is complete, dissolve the polymer in diethyl ether and precipitate it in acetonitrile. Repeat this process three times and separate the liquids. Collect the lower liquid and evaporate the solvent to obtain dendritic polysilazane. Add the dendritic polysilazane to toluene at 3.4~4.1 times its mass, and then add 0.45%~0.55% benzoyl peroxide at its mass. Stir until homogeneous to prepare an impregnation solution for later use. S3. Place the SiC-coated modified graphite substrate into a vacuum impregnation tank, evacuate to -0.093~-0.097MPa and maintain for 28~32min; inject impregnation liquid until the substrate is completely submerged, turn on ultraviolet light at 365nm with an intensity of 9~11mW / cm², and impregnate in vacuum for 1.8~2.2h. Turn off the ultraviolet light, slowly release to normal pressure, and continue impregnation for 0.8~1.2h. Remove the impregnated substrate, air dry naturally for 22~26h, then dry at 58~62℃ for 1.8~2.2h and 78~82℃ for 1.8~2.2h to remove residual solvent. Place the pre-dried sample into a programmed temperature oven and cure by gradient temperature increase. Cool naturally to room temperature to obtain the composite-coated modified graphite material.

2. The high-performance silicon carbide coating embedding process according to claim 1, characterized in that, The embedding powder in S1 includes the following preparation steps: Weigh 10-20 μm SiC powder, 5-10 μm Si powder and 1-5 μm carbon powder in a mass ratio of 70:19~21:9~11, and ball mill and mix them evenly to obtain the embedding powder.

3. The high-performance silicon carbide coating embedding process according to claim 1, characterized in that, The programmed temperature rise conditions in S1 are as follows: Stage 1: 4.5~5.5℃ / min, rise to 490~510℃, hold for 28~32min; Stage 2: 2.8~3.2℃ / min, rise to 1440~1460℃, hold for 1.8~2.2h.

4. The high-performance silicon carbide coating embedding process according to claim 1, characterized in that, The programmed temperature rise conditions in S3 are as follows: Stage 1: 1.8~2.2℃ / min, rise to 118~122℃, hold for 0.8~1.2h; Stage 2: 1.8~2.2℃ / min, rise to 158~162℃, hold for 1.8~2.2h; Stage 3: 0.9~1.1℃ / min, rise to 178~182℃, hold for 2.8~3.2h.

5. The high-performance silicon carbide coating embedding process according to claim 1, characterized in that, The polymer monomer comprises the following preparation steps: Dimethylhydrochlorosilane is added to toluene at a mass ratio of 1:1.5~1.8 to prepare a dimethylhydrochlorosilane solution for later use; 4-amino-4'-methacrylate-based azobenzene, triethylamine, and hydroquinone are added to toluene at a mass ratio of 1:1.4~1.6:0.01%~0.05%:1.3~1.5; the mixture is stirred evenly at a temperature of -5~0℃, and the dimethylhydrochlorosilane solution is added dropwise. After the addition is complete, the mixture is reacted at a temperature of 25~35℃ for 4~5 hours. After the reaction is complete, the mixture is allowed to stand and precipitate, and the precipitate is filtered. Then, 0.05%~0.1% (by mass) of hydroquinone (4-amino-4'-methacrylate-based azobenzene) is added to the filtrate. The mixture is then separated by rotary evaporation and silica gel column chromatography to obtain the polymer monomer.

6. The high-performance silicon carbide coating embedding process according to claim 5, characterized in that, The mass ratio between the 4-amino-4'-methacrylate-based azobenzene and dimethylhydrochlorosilane is 1.35~1.45:

1.

7. The high-performance silicon carbide coating embedding process according to claim 5, characterized in that, The eluent used in the silica gel column chromatography separation is petroleum ether: ethyl acetate = 15:1, by volume.

8. A composite coating modified graphite material, characterized in that, It is prepared by the high-performance silicon carbide coating embedding process described in any one of claims 1 to 7.