A method for preparing high-performance silicon carbide coating on the surface of carbon fiber thermal insulation material

Abstract

The present application relates to a kind of on the surface of carbon fiber thermal insulation material preparation high-performance silicon carbide coating method, comprising: 1) carbon fiber thermal insulation material surface is treated to form carbon hardening layer by carbon hardening;2) using coating glue one is coated to the surface of hardening coating and forms first transition coating;3) using coating glue two is coated to the surface of first transition coating and forms second transition coating;Through graphitization processing generates silicon carbide;4) on first transition coating and second transition coating carbon vapor deposition is carried out, and then second transition coating is formed gas phase deposition carbon coating;5) on gas phase deposition carbon coating silicon carbide vapor deposition is formed, and forms silicon carbide vapor deposition coating.The prepared high-performance silicon carbide coating has the carbon fiber thermal insulation material with high-performance silicon carbide coating and has excellent heat insulation performance and very strong oxidation resistance.

Description

Technical Field

[0001] This invention relates to the field of functional coating preparation technology, and in particular to a method for preparing a high-performance (highly dense and highly antioxidant) silicon carbide coating on the surface of carbon fiber insulation materials. Background Technology

[0002] With the continuous growth of global energy demand, energy conservation and environmental protection have become important themes in global development. Against this backdrop, the application of high-efficiency thermal insulation materials is becoming increasingly widespread, especially in fields such as photovoltaics, semiconductors, optical fibers, sapphire, and high-temperature, high-vacuum heat treatment. Monocrystalline silicon, as a photovoltaic power generation material, possesses high photoelectric conversion efficiency and significant commercial advantages, and has become the mainstream material for solar photovoltaic power generation. The thermal field system is the most important component of the monocrystalline furnace, mainly composed of graphite materials, carbon-carbon composite materials, and carbon fiber insulation materials. During the Czochralski process of growing monocrystalline silicon, the melting of silicon material generates silicon vapor and molten silicon splashes, causing silicification erosion of the carbon-carbon thermal field material. This severely affects the mechanical properties and service life of the carbon-carbon thermal field material, easily leading to cracking and pulverization of carbon-carbon components. Furthermore, the growth of third-generation and semi-thin silicon carbide crystals and epitaxy causes severe corrosion and oxidation of both graphite and carbon fiber insulation materials, easily leading to product cracking, brittleness, and pulverization, significantly shortening their service life.

[0003] To address these issues, researchers have attempted to prepare protective coatings on the surface of carbon fiber insulation materials. Common methods include attaching graphite foil, large-tow carbon cloth, or carbon-based coatings to the material surface. However, these methods still have some limitations, such as the coatings being prone to cracking and peeling, and graphite foil and carbon cloth being prone to delamination and peeling, making it difficult to simultaneously meet the performance requirements of insulation, ablation resistance, and oxidation resistance under high-temperature environments.

[0004] Silicon carbide coatings, due to their excellent thermal shock resistance and wear resistance, have become the preferred surface coating for carbon-carbon thermal field materials. However, their application in low-density carbon fiber insulation materials cannot be simply replicated. Issues need to be addressed, such as the impact of silicon carbide infiltration into the substrate on the thermal insulation performance of the carbon fiber, prevention of fiber oxidation and corrosion, influence on coating thickness and density uniformity, and matching with thermal expansion. Therefore, a new method is needed to form a dense and stable coating on the surface of carbon fiber insulation materials, effectively improving the material's high-temperature oxidation resistance and resisting the erosion of reactive gases. This is currently a key research focus and challenge. This is because it is necessary to solve not only the interfacial bonding problem between the coating and the substrate but also to consider factors such as coating thickness uniformity and density control to meet the performance requirements of different application scenarios.

[0005] Regarding the question of how to improve the bonding strength and density of silicon carbide coatings with carbon fiber insulation materials, some research results have been achieved. For example:

[0006] Chinese patent application CN109824374A discloses a method for preparing a high-performance silicon carbide coating on the surface of a carbon / carbon composite insulation material. This method involves pretreatment of the carbon / carbon composite insulation material blank, application of a coating slurry, ceramicization, carbon deposition, and high-temperature sintering to produce a silicon carbide coating that is firmly bonded to the carbon / carbon composite insulation material matrix. However, this method still has room for optimization in the formulation of the silicon carbide coating slurry. The product lacks sufficient density, and during use, silicon vapor can easily enter the coating and substrate through the pores of the coating, causing the coating to powder and peel off, and the substrate to powder and crack.

[0007] Chinese patent application CN111217616A discloses a method for preparing a C / SiC structural material with near-zero expansion characteristics. This method involves preparing a pyrolytic carbon interface layer on the surface of fiber bundles using a chemical vapor infiltration process, depositing silicon carbide on the interface phase surface, rapidly preparing a multiphase ceramic matrix using a slurry infiltration combined with reactive melt infiltration process, and finally sealing the surface with a silicon carbide coating prepared by chemical vapor deposition. However, this method still needs improvement in the preparation process of the silicide ceramic matrix. The resulting product is difficult to use in low-density carbon fiber insulation materials, and the matrix reacts with some silicon during the reaction process, leading to oxidation and embrittlement, thus losing its insulation properties.

[0008] In summary, the existing technology has the following problems:

[0009] 1. The existing silicon carbide coating has insufficient bonding strength with the carbon fiber insulation material matrix. The thermal expansion coefficients of the silicon carbide coating and the matrix are inconsistent, which can easily lead to cracking and peeling of the coating, affecting the overall performance and service life of the insulation material.

[0010] 2. Existing silicon carbide coatings are difficult to meet the requirements of excellent thermal insulation, ablation resistance and oxidation resistance at the same time in high-temperature environments, and cannot effectively protect carbon fiber insulation materials from the erosion of carbon and fibers in the coating by silicon vapor.

[0011] 3. The coating's density and compactness are not ideal, making it difficult to achieve uniform coating density and optimal compactness, which can easily lead to localized cracking during use.

[0012] 4. Existing preparation methods still need improvement in terms of coating thickness uniformity, interfacial layer performance, and composite material purity, making it difficult to meet the performance requirements of different application scenarios;

[0013] 5. Existing silicon carbide coatings need further improvement in terms of high temperature resistance and corrosion resistance, making it difficult to meet the requirements for long-term stable use in harsher environments. They are prone to premature oxidation and peeling, resulting in product contamination. Summary of the Invention

[0014] To address the problems in existing technologies, such as insufficient bonding between the silicon carbide coating and the carbon fiber insulation material matrix leading to cracks and peeling, and poor coating uniformity and density resulting in localized cracking, poor high-temperature oxidation resistance, inability to maintain long-term stable use, and easy contamination of products due to coating peeling, this invention provides a method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation materials. This method prepares a highly dense silicon carbide coating with high oxidation resistance on the surface of carbon fiber insulation materials, exhibiting excellent thermal insulation performance and strong oxidation resistance.

[0015] To achieve the above objectives, the present invention employs the following technical solution:

[0016] A method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material includes the following steps:

[0017] 1) Carbon hardening treatment is applied to the surface of carbon fiber insulation material by using a hardening coating adhesive composed of carbon fiber powder, carbon nanotubes, resin, dispersant, crosslinking agent and water, which is applied to the surface of carbon fiber insulation material and forms a carbon hardened layer after curing.

[0018] 2) A coating adhesive consisting of carbon fiber powder, silicon carbide powder, resin, silicon powder, dispersant, crosslinking agent and water is uniformly applied to the surface of the hardened coating and cured to form the first transition coating.

[0019] 3) A coating adhesive composed of carbon fiber powder, silicon carbide fine powder, resin, silicon fine powder, dispersant, crosslinking agent and water is uniformly coated onto the surface of the first transition coating, and after curing, a second transition coating is formed; graphitization treatment is used to allow carbon and silicon to fully react and generate silicon carbide;

[0020] 4) Carbon vapor deposition is performed on the first and second transition coatings, and then a denser vapor-deposited carbon coating is formed on the second transition coating. The density of the vapor-deposited carbon coating is 1.5–2.2 g / cm³. 3 ;

[0021] 5) Silicon carbide vapor deposition is performed on the vapor-deposited carbon coating to form a silicon carbide vapor-deposited coating with a density of 2.8–3.2 g / cm³. 3 .

[0022] In step 1), the hardening coating adhesive is composed of the following components in parts by weight: 20-60 parts carbon fiber powder, 10-30 parts carbon nanotubes, 20-60 parts resin, 0.2-3 parts dispersant, 0.1-1.5 parts crosslinking agent, and 35-360 parts water; wherein the particle size of the carbon fiber powder is 3-6 μm; the preparation process of the hardening coating adhesive is as follows: first, mix the carbon fiber powder and carbon nanotubes, then add water and stir evenly, then add the dispersant and resin and mix evenly, and finally add the crosslinking agent and mix evenly.

[0023] The specific process of step 1) is as follows:

[0024] 1-1. Clean the dust off the surface of the carbon fiber insulation material after processing, and ultrasonically clean it with ethanol and acetone for 15-20 minutes in sequence.

[0025] 1-2. Dry the cleaned carbon fiber insulation material, apply the hardening coating adhesive evenly to the surface of the carbon fiber insulation material, and after the penetration depth reaches 0.5-3mm, cure and shape it at 160-200℃, and let it cool naturally to room temperature to obtain a carbon hardened layer with a thickness of 0.5-3mm.

[0026] 1-3. Use sandpaper to sand the surface of the carbon-hardened layer to clean away any particles.

[0027] In step 2), the coating adhesive is composed of the following components by weight: 40-80 parts carbon fiber powder, 10-30 parts silicon carbide powder, 10-30 parts silicon powder, 40-80 parts resin, 0.2-3 parts dispersant, 0.1-1.5 parts crosslinking agent, and 70-528 parts water; wherein the particle size of the carbon fiber powder is 1-4 μm, the particle size of the silicon carbide powder is 2-6 μm, and the particle size of the silicon powder is 2-6 μm; the preparation process of the coating adhesive is as follows: first, the carbon fiber powder, silicon carbide powder, and silicon powder are mixed, then water is added and stirred evenly, then the dispersant and resin are added and mixed evenly, and finally the crosslinking agent is added and stirred for 4-6 hours to obtain the coating adhesive.

[0028] The specific process of step 2) is as follows:

[0029] 2-1. Apply the coating adhesive evenly to the surface of the carbon-cured layer, with a coating thickness of 40-80 μm;

[0030] 2-2. The carbon fiber insulation material after coating with the first coating adhesive is dried at 60-70℃ for 2-3 hours, then heated to 140-160℃ for 2-4 hours, and then carbonized at 600-900℃ to obtain a first transition coating with a thickness of 40-80μm.

[0031] In step 3), the coating adhesive II is composed of the following components by weight proportions: 10-30 parts carbon fiber powder, 30-60 parts silicon carbide fine powder, 10-30 parts silicon fine powder, 30-60 parts resin, 0.2-3 parts dispersant, 0.1-1.5 parts crosslinking agent, and 59-432 parts water; wherein, the particle size of the carbon fiber powder is 0.3-1.5 μm, the particle size of the silicon carbide fine powder is 0.5-1.2 μm, and the particle size of the silicon fine powder is 0.5-1.2 μm; the preparation process of coating adhesive II is as follows: first, the carbon fiber powder, silicon carbide fine powder, and silicon fine powder are mixed and then water is added and stirred evenly, then the dispersant and resin are added and mixed evenly, and finally the crosslinking agent is added and mixed for 4-6 hours to obtain coating adhesive II.

[0032] The specific process of step 3) is as follows:

[0033] 3-1. Apply coating adhesive 2 evenly to the surface of the first transition coating, with a coating thickness of 10-40 μm;

[0034] 3-2. The carbon fiber insulation material after coating with the second coating adhesive is dried at 60-70℃ for 2-3 hours, then heated to 140-160℃ for 2-4 hours, and then carbonized at 600-900℃ to obtain a second transition coating with a thickness of 10-40μm; then graphitization is carried out at 1600-2200℃ to allow carbon and silicon to fully react and generate silicon carbide.

[0035] In steps 1) to 3), the resin is one or more of epoxy resin, polybutadiene resin, phenolic resin, unsaturated polyester resin, polyurethane resin, unsaturated polyester resin, and furan resin; the crosslinking agent is one or more of dicumyl peroxide, dicumyl peroxide, diethylenetriamine, diethylenetriamine, polyisocyanate, alkyl isocyanate, glycidyl ether, phthalic anhydride, and tetrachlorophthalic anhydride; and the dispersant is one or more of gelatin, starch, polyvinyl alcohol, polyether, and polyoxyethylene alkylphenol ether.

[0036] The specific process of step 4) is as follows:

[0037] 4-1. Place the carbon fiber insulation material treated in step 3) into a chemical vapor deposition furnace;

[0038] 4-2. Nitrogen and a mixture of methane / propane / propylene are introduced into the furnace at a flow rate ratio of 3 to 10:1 and a pressure of 50 to 2000 Pa.

[0039] 4-3. The chemical vapor deposition furnace is heated to 900-1100℃ at a heating rate of 1-10℃ / min, and the deposition is carried out for 10-30 hours. The depth of penetration into the first and second transition coatings is 50-120μm. Then, a vapor-deposited carbon coating with a thickness of 1-10μm is deposited on the surface of the second transition coating, and the mixture is naturally cooled to room temperature.

[0040] The specific process of step 5) is as follows:

[0041] 5-1. Place the carbon fiber insulation material treated in step 4) into a silicon carbide chemical vapor deposition furnace;

[0042] 5-2. A mixture of nitrogen, methane / propane / propylene, and silane / dichlorosilane / trichlorosilane is introduced into the furnace at a flow rate ratio of 3 to 9:1:1; or a mixture of nitrogen and hexamethyldisilane is introduced at a flow rate ratio of 3 to 9:1; the pressure of the mixed gas is 200 to 3000 Pa.

[0043] 5-3. The silicon carbide chemical vapor deposition furnace is heated to 800-1500℃ at a heating rate of 1-10℃ / min, and the deposition is carried out for 20-50h, controlling the penetration depth of the silicon carbide deposition coating to be 1-10μm; then a silicon carbide vapor deposition coating with a thickness of 10-70μm is deposited on the surface of the silicon carbide deposition coating, and the coating is naturally cooled to room temperature.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] 1) The surface of carbon fiber insulation material is first treated with a carbon hardening layer, and then a crosslinking agent is used to promote the silicon-carbon reaction to generate silicon carbide, forming a first transition coating and a second transition coating with high strength and density. This effectively improves the interfacial bonding force between the coating and the substrate, solves the problem of easy cracking and peeling of the coating in the prior art, and extends the service life of the material.

[0046] 2) The structure design of the double transition coating is adopted. By performing carbon vapor deposition on the first and second transition coatings to form a dense coating, the density and compactness of the coating are effectively improved, the dense uniformity of the coating is achieved, and the thermal insulation performance and ablation resistance of the coating are significantly enhanced.

[0047] 3) By controlling the thickness (1–10 μm) and density (1.5–2.2 μm) of the vapor-deposited carbon coating. g / cm 3 This process ensures that the resulting vapor-deposited carbon coating has good thickness uniformity and physical properties, further solving the problems of adhesion between the substrate and the silicon carbide coating as well as thermal expansion matching, and resolving the issue of easy cracking in silicon carbide coatings.

[0048] 4) The use of crosslinking agents enhances the connection and reaction between silicon and carbon, promoting the reaction of some silicon and carbon to form silicon carbide, and the combination of some silicon and carbon through crosslinking agents to form strong bonding bonds, preventing particle shedding and forming a stable transition layer structure. This effectively improves the high-temperature oxidation resistance of the coating, and the thermal insulation material can remain stable in an oxygen atmosphere of 500-700℃, significantly extending the service life of the material in high-temperature environments.

[0049] 5) The prepared stable and uniform silicon carbide vapor deposition coating has good corrosion resistance and can effectively resist the erosion of silicon vapor, which significantly improves the working stability of the insulation material in harsh environments such as single crystal silicon growth furnace and extends its service life. Attached Figure Description

[0050] Figure 1 This is a surface electron microscope image of the silicon carbide vapor-deposited coating described in this invention.

[0051] Figure 2 This is a cross-sectional electron microscope image of the silicon carbide vapor-deposited coating described in this invention. Detailed Implementation

[0052] The present invention discloses a method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material, comprising the following steps:

[0053] 1) Carbon hardening treatment is applied to the surface of carbon fiber insulation material by using a hardening coating adhesive composed of carbon fiber powder, carbon nanotubes, resin, dispersant, crosslinking agent and water, which is applied to the surface of carbon fiber insulation material and forms a carbon hardened layer after curing.

[0054] 2) A coating adhesive consisting of carbon fiber powder, silicon carbide powder, resin, silicon powder, dispersant, crosslinking agent and water is uniformly applied to the surface of the hardened coating and cured to form the first transition coating.

[0055] 3) A coating adhesive composed of carbon fiber powder, silicon carbide fine powder, resin, silicon fine powder, dispersant, crosslinking agent and water is uniformly coated onto the surface of the first transition coating, and after curing, a second transition coating is formed; graphitization treatment is used to allow carbon and silicon to fully react and generate silicon carbide;

[0056] 4) Carbon vapor deposition is performed on the first and second transition coatings, and then a denser vapor-deposited carbon coating is formed on the second transition coating. The density of the vapor-deposited carbon coating is 1.5–2.2 g / cm³. 3 ;

[0057] 5) Silicon carbide vapor deposition is performed on the vapor-deposited carbon coating to form a silicon carbide vapor-deposited coating with a density of 2.8–3.2 g / cm³. 3 .

[0058] In step 1), the hardening coating adhesive is composed of the following components in parts by weight: 20-60 parts carbon fiber powder, 10-30 parts carbon nanotubes, 20-60 parts resin, 0.2-3 parts dispersant, 0.1-1.5 parts crosslinking agent, and 35-360 parts water; wherein the particle size of the carbon fiber powder is 3-6 μm; the preparation process of the hardening coating adhesive is as follows: first, mix the carbon fiber powder and carbon nanotubes, then add water and stir evenly, then add the dispersant and resin and mix evenly, and finally add the crosslinking agent and mix evenly.

[0059] The specific process of step 1) is as follows:

[0060] 1-1. Clean the dust off the surface of the carbon fiber insulation material after processing, and ultrasonically clean it with ethanol and acetone for 15-20 minutes in sequence.

[0061] 1-2. Dry the cleaned carbon fiber insulation material, apply the hardening coating adhesive evenly to the surface of the carbon fiber insulation material, and after the penetration depth reaches 0.5-3mm, cure and shape it at 160-200℃, and let it cool naturally to room temperature to obtain a carbon hardened layer with a thickness of 0.5-3mm.

[0062] 1-3. Use sandpaper to sand the surface of the carbon-hardened layer to clean away any particles.

[0063] In step 2), the coating adhesive is composed of the following components by weight: 40-80 parts carbon fiber powder, 10-30 parts silicon carbide powder, 10-30 parts silicon powder, 40-80 parts resin, 0.2-3 parts dispersant, 0.1-1.5 parts crosslinking agent, and 70-528 parts water; wherein the particle size of the carbon fiber powder is 1-4 μm, the particle size of the silicon carbide powder is 2-6 μm, and the particle size of the silicon powder is 2-6 μm; the preparation process of the coating adhesive is as follows: first, the carbon fiber powder, silicon carbide powder, and silicon powder are mixed, then water is added and stirred evenly, then the dispersant and resin are added and mixed evenly, and finally the crosslinking agent is added and stirred for 4-6 hours to obtain the coating adhesive.

[0064] The specific process of step 2) is as follows:

[0065] 2-1. Apply the coating adhesive evenly to the surface of the carbon-cured layer, with a coating thickness of 40-80 μm;

[0066] 2-2. The carbon fiber insulation material after coating with the first coating adhesive is dried at 60-70℃ for 2-3 hours, then heated to 140-160℃ for 2-4 hours, and then carbonized at 600-900℃ to obtain a first transition coating with a thickness of 40-80μm.

[0067] In step 3), the coating adhesive II is composed of the following components by weight proportions: 10-30 parts carbon fiber powder, 30-60 parts silicon carbide fine powder, 10-30 parts silicon fine powder, 30-60 parts resin, 0.2-3 parts dispersant, 0.1-1.5 parts crosslinking agent, and 59-432 parts water; wherein, the particle size of the carbon fiber powder is 0.3-1.5 μm, the particle size of the silicon carbide fine powder is 0.5-1.2 μm, and the particle size of the silicon fine powder is 0.5-1.2 μm; the preparation process of coating adhesive II is as follows: first, the carbon fiber powder, silicon carbide fine powder, and silicon fine powder are mixed and then water is added and stirred evenly, then the dispersant and resin are added and mixed evenly, and finally the crosslinking agent is added and mixed for 4-6 hours to obtain coating adhesive II.

[0068] The specific process of step 3) is as follows:

[0069] 3-1. Apply coating adhesive 2 evenly to the surface of the first transition coating, with a coating thickness of 10-40 μm;

[0070] 3-2. The carbon fiber insulation material after coating with the second coating adhesive is dried at 60-70℃ for 2-3 hours, then heated to 140-160℃ for 2-4 hours, and then carbonized at 600-900℃ to obtain a second transition coating with a thickness of 10-40μm; then graphitization is carried out at 1600-2200℃ to allow carbon and silicon to fully react and generate silicon carbide.

[0071] In steps 1) to 3), the resin is one or more of epoxy resin, polybutadiene resin, phenolic resin, unsaturated polyester resin, polyurethane resin, unsaturated polyester resin, and furan resin; the crosslinking agent is one or more of dicumyl peroxide, dicumyl peroxide, diethylenetriamine, diethylenetriamine, polyisocyanate, alkyl isocyanate, glycidyl ether, phthalic anhydride, and tetrachlorophthalic anhydride; and the dispersant is one or more of gelatin, starch, polyvinyl alcohol, polyether, and polyoxyethylene alkylphenol ether.

[0072] The specific process of step 4) is as follows:

[0073] 4-1. Place the carbon fiber insulation material treated in step 3) into a chemical vapor deposition furnace;

[0074] 4-2. Nitrogen and a mixture of methane / propane / propylene are introduced into the furnace at a flow rate ratio of 3 to 10:1 and a pressure of 50 to 2000 Pa.

[0075] 4-3. The chemical vapor deposition furnace is heated to 900-1100℃ at a heating rate of 1-10℃ / min, and the deposition is carried out for 10-30 hours. The depth of penetration into the first and second transition coatings is 50-120μm. Then, a vapor-deposited carbon coating with a thickness of 1-10μm is deposited on the surface of the second transition coating, and the mixture is naturally cooled to room temperature.

[0076] The specific process of step 5) is as follows:

[0077] 5-1. Place the carbon fiber insulation material treated in step 4) into a silicon carbide chemical vapor deposition furnace;

[0078] 5-2. A mixture of nitrogen, methane / propane / propylene, and silane / dichlorosilane / trichlorosilane is introduced into the furnace at a flow rate ratio of 3 to 9:1:1; or a mixture of nitrogen and hexamethyldisilane is introduced at a flow rate ratio of 3 to 9:1; the pressure of the mixed gas is 200 to 3000 Pa.

[0079] 5-3. The silicon carbide chemical vapor deposition furnace is heated to 800-1500℃ at a heating rate of 1-10℃ / min, and the deposition is carried out for 20-50h, controlling the penetration depth of the silicon carbide deposition coating to be 1-10μm; then a silicon carbide vapor deposition coating with a thickness of 10-70μm is deposited on the surface of the silicon carbide deposition coating, and the coating is naturally cooled to room temperature.

[0080] The surface electron microscope image of the silicon carbide vapor-deposited coating of the present invention is shown below. Figure 1 As shown, the cross-sectional electron microscope image of the silicon carbide vapor-deposited coating of the present invention is as follows. Figure 2 As shown.

[0081] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0082] In the following examples, all original reagent materials are commercially available. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or are performed according to the conditions recommended by the instrument manufacturer.

[0083]

Example 1

[0084] In this embodiment, the process of preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material is as follows:

[0085] Step 1: Perform carbon hardening treatment on the surface of the carbon fiber insulation material, as follows:

[0086] Step 1-1: Clean the dust off the surface of the processed carbon fiber insulation material by ultrasonic cleaning with ethanol and acetone for 20 minutes in sequence.

[0087] Steps 1-2: Mix 40g of carbon fiber powder with a particle size of 4μm and 20g of carbon nanotubes evenly, then add 140g of water and mix evenly. Then add 2g of gelatin (dispersant) and 50g of epoxy resin. Finally, add 1.0g of diethylenetriamine (crosslinking agent) and mix evenly to obtain the hardened coating adhesive.

[0088] Steps 1-3: Dry the cleaned carbon fiber insulation material, apply the hardening coating adhesive evenly to the surface of the carbon fiber insulation material, control the penetration depth to 2mm, then cure and shape it at 180℃, and let it cool naturally to room temperature to form a carbon hardened layer.

[0089] Steps 1-4: Use sandpaper to sand the surface of the carbon-hardened layer to clean off any particles.

[0090] Step 2: Apply the coating adhesive evenly to the surface of the carbon-cured coating to form the first transition coating. The specific process is as follows:

[0091] Step 2-1: Mix 50g of carbon fiber powder with a particle size of 2μm, 20g of silicon carbide powder with a particle size of 2μm, and 20g of silicon powder with a particle size of 2μm evenly. Then add 90g of water and mix evenly. Add 2g of starch (dispersant) and stir evenly. Then add 70g of epoxy resin and 1g of diethylenetriamine (crosslinking agent). Mix and stir for 4 hours to obtain coating adhesive one.

[0092] Step 2-2: Apply coating adhesive evenly to the surface of the carbon hardened layer, with a coating thickness of 50μm;

[0093] Steps 2-3: Dry at 70℃ for 3 hours, then heat to 150℃ for 4 hours, and then carbonize at 800℃ to form the first transition coating.

[0094] Step 3: Apply coating adhesive 2 evenly to the surface of the first transition coating to form the second transition coating, as detailed below;

[0095] Step 3-1: Mix 20g of carbon fiber powder with a particle size of 0.5μm, 40g of silicon carbide fine powder with a particle size of 0.5μm, and 20g of silicon fine powder with a particle size of 0.5μm evenly. Then add 160g of water and mix evenly. Add 2g of starch (dispersant) and stir evenly. Then add 60g of epoxy resin and 1g of diethylenetriamine (crosslinking agent) and stir for 4 hours to obtain coating adhesive II.

[0096] Step 3-2: Apply coating adhesive 2 evenly to the surface of the first transition coating, with a coating thickness of 30μm;

[0097] Step 3-3: Dry at 70℃ for 2 hours, then heat to 150℃ for 4 hours, and then carbonize at 800℃ to form a second transition coating. Then, graphitize at 1800℃ to allow carbon and silicon to fully react and generate silicon carbide.

[0098] Step 4: Perform carbon vapor deposition on the first and second transition coatings, and then form a denser vapor-deposited carbon coating on the second transition coating, as detailed below:

[0099] Step 4-1: Place the carbon fiber insulation material after the preparation of the second transition coating in a chemical vapor deposition furnace;

[0100] Step 4-2: After the set temperature is reached, a mixture of nitrogen and methane is introduced with a flow rate ratio of 5:1 and a pressure of 1500 Pa.

[0101] Step 4-3: The chemical vapor deposition furnace is heated to 1100℃ at a heating rate of 5℃ / min, and deposition is carried out for 25 hours. The penetration depth of both the first and second transition coatings is 80μm. Then, a denser vapor-deposited carbon coating with a thickness of 8μm is deposited on the second transition coating. The mixture is then allowed to cool naturally to room temperature. The density of the vapor-deposited carbon coating is 2.1g / cm³. 3 ;

[0102] Step 5: Perform silicon carbide vapor deposition on the vapor-deposited carbon coating to form a silicon carbide vapor-deposited coating, as detailed below:

[0103] Step 5-1: Place the carbon fiber insulation material with vapor-deposited carbon coating in a silicon carbide chemical vapor deposition furnace;

[0104] Step 5-2: After the furnace temperature reaches the set temperature, a mixture of nitrogen, methane and silane is introduced. The flow rate ratio of the three gases is 7:1:1, and the pressure of the mixed gas is 1200Pa.

[0105] Step 5-3: Increase the temperature to 1300℃ at a heating rate of 5℃ / min, and deposit for 20 hours. The penetration depth of the silicon carbide deposition coating is 5μm. Then, a dense, oxidation-resistant silicon carbide vapor deposition coating with a thickness of 15μm is formed on the silicon carbide deposition coating. Allow it to cool naturally to room temperature. The density of the silicon carbide vapor deposition coating is 3.1g / cm³. 3 .

[0106] In this embodiment, the silicon carbide vapor-deposited coating prepared on the surface of the carbon fiber insulation material sample is smooth and free from cracks and powdering. In the oxidation resistance test at 600°C, the weight loss after burning at 600°C for 8 hours in air is 0.04% (in contrast, the weight loss of the uncoated carbon fiber insulation material sample after burning at 600°C for 8 hours in air is 35.2%).

[0107] In conclusion, the carbon fiber insulation material with silicon carbide vapor deposition coating prepared in this embodiment can effectively prevent air from directly contacting the surface of the carbon fiber insulation material, prevent the carbon fiber insulation material from oxidation and ablation, and has excellent anti-oxidation and anti-corrosion properties, which can significantly improve the service life of the carbon fiber insulation material.

[0108]

Example 2

[0109] In this embodiment, the process of preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material is as follows:

[0110] Step 1: Perform carbon hardening treatment on the surface of the carbon fiber insulation material, as follows:

[0111] Step 1-1: Clean the dust off the surface of the processed carbon fiber insulation material by ultrasonic cleaning with ethanol and acetone for 20 minutes in sequence.

[0112] Steps 1-2: Mix 40g of 4μm carbon fiber powder and 20g of carbon nanotubes evenly, then add 110g of water and mix evenly. Then add 2g of polyvinyl alcohol (dispersant) and 50g of polyurethane resin. Finally, add 1.0g of dicumyl oxide (crosslinking agent) and mix evenly to obtain the hardened coating adhesive.

[0113] Steps 1-3: Dry the cleaned carbon fiber insulation material, apply the hardening coating adhesive evenly to the surface of the carbon fiber insulation material, control the penetration depth to 2mm, then cure and shape it at 180℃, and let it cool naturally to room temperature to form a carbon hardened layer.

[0114] Steps 1-4: Use sandpaper to sand the surface of the carbon-hardened layer to clean off any particles.

[0115] Step 2: Apply the coating adhesive evenly to the surface of the carbon-cured coating to form the first transition coating. The specific process is as follows:

[0116] Step 2-1: Mix 50g of carbon fiber powder with a particle size of 2μm, 25g of silicon carbide powder with a particle size of 2μm, and 25g of silicon powder with a particle size of 2μm evenly. Then add 140g of water and mix evenly. Add 1.7g of polyvinyl alcohol (dispersant) and 70g of polyurethane resin. Finally, add 1.0g of dicumyl oxide (crosslinking agent) and mix and stir for 5 hours to obtain coating adhesive one.

[0117] Step 2-2: Apply coating adhesive evenly to the surface of the carbon hardened layer, with a coating thickness of 60μm;

[0118] Steps 2-3: Dry at 70℃ for 2 hours, then heat to 150℃ for 4 hours, and then carbonize at 800℃ to form the first transition coating.

[0119] Step 3: Apply coating adhesive 2 evenly to the surface of the first transition coating to form the second transition coating, as detailed below;

[0120] Step 3-1: Mix 20g of carbon fiber powder with a particle size of 0.5μm, 50g of silicon carbide fine powder with a particle size of 0.5μm, and 20g of silicon fine powder with a particle size of 0.5μm evenly. Then add 120g of water and mix evenly. Add 1.5g of polyvinyl alcohol (dispersant) and 60g of polyurethane resin. Finally, add 1.4g of dicumyl oxide (crosslinking agent) and mix and stir for 6 hours to obtain coating adhesive II.

[0121] Step 3-2: Apply coating adhesive 2 evenly to the surface of the first transition coating, with a coating thickness of 40μm;

[0122] Step 3-3: Dry at 70℃ for 2 hours, then heat to 150℃ for 4 hours, and then carbonize at 800℃ to form a second transition coating. Then, graphitize at 1800℃ to allow carbon and silicon to fully react and generate silicon carbide.

[0123] Step 4: Perform carbon vapor deposition on the first transition coating and the second transition coating, and then form a denser vapor-deposited carbon coating on the second transition coating.

[0124] Step 4-1: Place the carbon fiber insulation material after the preparation of the second transition coating in a chemical vapor deposition furnace;

[0125] Step 4-2: After the set temperature is reached, a mixture of nitrogen and methane is introduced, with a flow rate ratio of 5:1 and a pressure of 1500 Pa. Details are as follows:

[0126] Step 4-3: The chemical vapor deposition furnace is heated to 1100℃ at a heating rate of 5℃ / min, and deposition is carried out for 30 hours. The depth of penetration into both the first and second transition coatings is 100μm. Then, a denser vapor-deposited carbon coating with a thickness of 10μm is deposited on the second transition coating. The mixture is then allowed to cool naturally to room temperature. The density of the vapor-deposited carbon coating is 2.1g / cm³. 3 .

[0127] Step 5: Perform silicon carbide vapor deposition on the vapor-deposited carbon coating to form a silicon carbide vapor-deposited coating, as detailed below:

[0128] Step 5-1: Place the carbon fiber insulation material with vapor-deposited carbon coating in a silicon carbide chemical vapor deposition furnace;

[0129] Step 5-2: After the furnace temperature reaches the set temperature, a mixture of nitrogen, propane and silane is introduced. The flow rate ratio of the three gases is 7:1:1, and the pressure of the mixed gas is 1200Pa.

[0130] Step 5-3: Heat to 1250℃ at a heating rate of 5℃ / min, hold for 25 hours, and the penetration depth of the silicon carbide deposited coating is 8μm; then form a dense, oxidation-resistant silicon carbide vapor deposition coating with a thickness of 20μm on the silicon carbide deposited coating, and allow it to cool naturally to room temperature. The density of the silicon carbide vapor deposition coating is 3.1g / cm³. 3 .

[0131] In this embodiment, the silicon carbide vapor-deposited coating prepared on the surface of the carbon fiber insulation material sample is smooth and free from cracks and powdering. In the oxidation resistance test at 600°C, the weight loss after burning at 600°C for 8 hours in air is 0.02% (in contrast, the weight loss of the uncoated carbon fiber insulation material sample after burning at 600°C for 8 hours in air is 36.8%).

[0132] In conclusion, the carbon fiber insulation material with silicon carbide vapor deposition coating prepared in this embodiment can effectively prevent air from directly contacting the surface of the carbon fiber insulation material, prevent the carbon fiber insulation material from oxidation and ablation, and has excellent anti-oxidation and anti-corrosion properties, which can significantly improve the service life of the carbon fiber insulation material.

[0133]

Example 3

[0134] In this embodiment, the process of preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material is as follows:

[0135] Step 1: Perform carbon hardening treatment on the surface of the carbon fiber insulation material, as follows:

[0136] Step 1-1: Clean the dust off the surface of the processed carbon fiber insulation material by ultrasonic cleaning with ethanol and acetone for 20 minutes in sequence.

[0137] Steps 1-2: Mix 40g of carbon fiber powder with a particle size of 4μm and 25g of carbon nanotubes evenly, then add 150g of water and mix evenly. Then add 2.2g of gelatin (dispersant) and 50g of furan resin. Finally, add 1.0g of phthalic anhydride (crosslinking agent) and mix evenly to obtain a hardened coating adhesive.

[0138] Steps 1-3: Dry the cleaned carbon fiber insulation material, apply the hardening coating adhesive evenly to the surface of the carbon fiber insulation material, control the penetration depth to 2mm, then cure and shape it at 180℃, and let it cool naturally to room temperature to form a carbon hardened layer.

[0139] Steps 1-4: Use sandpaper to sand the surface of the carbon-hardened layer to clean off any particles.

[0140] Step 2: Apply the coating adhesive evenly to the surface of the carbon-cured coating to form the first transition coating. The specific process is as follows:

[0141] Step 2-1: Mix 50g of carbon fiber powder with a particle size of 2μm, 30g of silicon carbide powder with a particle size of 2μm, and 30g of silicon powder with a particle size of 2μm evenly. Then add 200g of water and mix evenly. Then add 2.6g of gelatin (dispersant) and 70g of furan resin. Finally, add 0.8g of phthalic anhydride (crosslinking agent). Mix and stir for 5 hours to obtain coating adhesive one.

[0142] Step 2-2: Apply coating adhesive evenly to the surface of the carbon hardened layer, with a coating thickness of 60μm;

[0143] Steps 2-3: Dry at 70℃ for 2 hours, then heat to 150℃ for 4 hours, and then carbonize at 800℃ to form the first transition coating.

[0144] Step 3: Apply coating adhesive 2 evenly to the surface of the first transition coating to form the second transition coating, as detailed below;

[0145] Step 3-1: Mix 20g of carbon fiber powder with a particle size of 0.5μm, 40g of fine silicon carbide with a particle size of 0.5μm, and 20g of fine silicon powder with a particle size of 0.5μm evenly. Then add 160g of water and mix evenly. Next, add 3.0g of gelatin (dispersant) and 35g of furan resin. Finally, add 1.3g of phthalic anhydride (crosslinking agent). Mix and stir for 4 hours to obtain coating adhesive 2.

[0146] Step 3-3: Dry at 70℃ for 2 hours, then heat to 150℃ for 4 hours, and then carbonize at 800℃ to form a second transition coating. Then, graphitize at 1900℃ to allow carbon and silicon to fully react and form silicon carbide.

[0147] Step 4: Perform carbon vapor deposition on the first and second transition coatings, and then form a denser vapor-deposited carbon coating on the second transition coating, as detailed below:

[0148] Step 4-1: Place the carbon fiber insulation material after the preparation of the second transition coating in a chemical vapor deposition furnace;

[0149] Step 4-2: After the set temperature is reached, a mixture of nitrogen and propane is introduced with a flow rate ratio of 9:1 and a pressure of 1200 Pa.

[0150] Step 4-3: The chemical vapor deposition furnace is heated to 1050℃ at a heating rate of 5℃ / min, and deposition is carried out for 28 hours. The depth of penetration into both the first and second transition coatings is 100μm. Then, a denser vapor-deposited carbon coating with a thickness of 8μm is deposited on the second transition coating. The mixture is then allowed to cool naturally to room temperature. The density of the vapor-deposited carbon coating is 2.1g / cm³. 3 .

[0151] Step 5: Perform silicon carbide vapor deposition on the vapor-deposited carbon coating to form a silicon carbide vapor-deposited coating, as detailed below:

[0152] Step 5-1: Place the carbon fiber insulation material with vapor-deposited carbon coating in a silicon carbide chemical vapor deposition furnace;

[0153] Step 5-2: After the furnace temperature reaches the set temperature, a mixture of nitrogen, propylene and silane is introduced. The flow rate ratio of the three gases is 7:1:1, and the pressure of the mixed gas is 1200Pa.

[0154] Step 5-3: Heat to 1200℃ at a heating rate of 5℃ / min, with a deposition time of 13 hours, resulting in a silicon carbide deposition coating penetration depth of 6μm; then form a dense, oxidation-resistant silicon carbide vapor deposition coating with a thickness of 20μm on the silicon carbide deposition coating, and allow it to cool naturally to room temperature. The density of the silicon carbide vapor deposition coating is 3.1 g / cm³. 3 .

[0155] In this embodiment, the silicon carbide vapor-deposited coating prepared on the surface of the carbon fiber insulation material sample is smooth and free from cracks and powdering. In the oxidation resistance test at 600°C, the weight loss after burning at 600°C for 8 hours in air is 0.025% (in contrast, the weight loss of the uncoated carbon fiber insulation material sample after burning at 600°C for 8 hours in air is 36.1%).

[0156] In conclusion, the carbon fiber insulation material with silicon carbide vapor deposition coating prepared in this embodiment can effectively prevent air from directly contacting the surface of the carbon fiber insulation material, prevent the carbon fiber insulation material from oxidation and ablation, and has excellent anti-oxidation and anti-corrosion properties, which can significantly improve the service life of the carbon fiber insulation material.

[0157] The above embodiments demonstrate that after preparing a high-density, high-oxidation-resistant silicon carbide coating on the surface of carbon fiber insulation material using the method described in this invention, the coated carbon fiber insulation material exhibits excellent thermal insulation performance, strong oxidation resistance, and reduces the problem of silicon carbide coating cracking.

[0158] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material, characterized in that, Includes the following steps: 1) Carbon hardening treatment is applied to the surface of carbon fiber insulation material using a hardening coating adhesive composed of carbon fiber powder, carbon nanotubes, resin, dispersant, crosslinking agent, and water. This adhesive is then applied to the surface of the carbon fiber insulation material and cured to form a carbon hardened layer. The hardening coating adhesive consists of the following components by weight: 20–60 parts carbon fiber powder, 10–30 parts carbon nanotubes, 20–60 parts resin, 0.2–3 parts dispersant, 0.1–1.5 parts crosslinking agent, and 35–360 parts water; wherein the particle size of the carbon fiber powder is 3–6 μm. 2) A coating adhesive, composed of carbon fiber powder, silicon carbide powder, resin, silicon powder, dispersant, crosslinking agent, and water, is uniformly applied to the surface of the hardened coating. After curing and carbonization, a first transition coating with a thickness of 40–80 μm is formed. The coating adhesive consists of the following components in parts by weight: 40–80 parts carbon fiber powder, 10–30 parts silicon carbide powder, 10–30 parts silicon powder, 40–80 parts resin, 0.2–3 parts dispersant, 0.1–1.5 parts crosslinking agent, and 70–528 parts water. The particle size of the carbon fiber powder is 1–4 μm, the particle size of the silicon carbide powder is 2–6 μm, and the particle size of the silicon powder is 2–6 μm. 3) A second coating adhesive, composed of carbon fiber powder, silicon carbide fine powder, resin, silicon fine powder, dispersant, crosslinking agent, and water, is uniformly coated onto the surface of the first transition coating. After curing and carbonization, a second transition coating with a thickness of 10–40 μm is formed. Graphitization treatment is used to allow carbon and silicon to fully react and generate silicon carbide. The second coating adhesive is composed of the following components in parts by weight: 10–30 parts carbon fiber powder, 30–60 parts silicon carbide fine powder, 10–30 parts silicon fine powder, 30–60 parts resin, 0.2–3 parts dispersant, 0.1–1.5 parts crosslinking agent, and 59–432 parts water. The particle size of the carbon fiber powder is 0.3–1.5 μm, the particle size of the silicon carbide fine powder is 0.5–1.2 μm, and the particle size of the silicon fine powder is 0.5–1.2 μm. 4) Carbon vapor deposition is performed on the first and second transition coatings, followed by deposition of a vapor-deposited carbon coating with a thickness of 1–10 μm on the surface of the second transition coating. The density of the vapor-deposited carbon coating is 1.5–2.2 g / cm³. 3 ; 5) Silicon carbide vapor deposition is performed on the vapor-deposited carbon coating to form a silicon carbide vapor-deposited coating with a thickness of 10–70 μm and a density of 2.8–3.2 g / cm³. 3 .

2. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, In step 1), the preparation process of the hardened coating adhesive is as follows: first, carbon fiber powder and carbon nanotubes are mixed and then water is added and stirred evenly; then, dispersant and resin are added and mixed evenly; finally, crosslinking agent is added and mixed evenly.

3. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, The specific process of step 1) is as follows: 1-1. Clean the dust off the surface of the carbon fiber insulation material after processing, and ultrasonically clean it with ethanol and acetone for 15-20 minutes in sequence. 1-2. Dry the cleaned carbon fiber insulation material, apply the hardening coating adhesive evenly to the surface of the carbon fiber insulation material, and after the penetration depth reaches 0.5-3mm, cure and shape it at 160-200℃, and let it cool naturally to room temperature to obtain a carbon hardened layer with a thickness of 0.5-3mm. 1-3. Use sandpaper to sand the surface of the carbon-hardened layer to clean away any particles.

4. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, In step 2), the preparation process of coating adhesive one is as follows: first, carbon fiber powder, silicon carbide powder and silicon powder are mixed and then water is added and stirred evenly. Then, dispersant and resin are added and mixed evenly. Finally, crosslinking agent is added and stirred for 4 to 6 hours to obtain coating adhesive one.

5. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, The specific process of step 2) is as follows: 2-1. Apply the coating adhesive evenly to the surface of the carbon-cured layer, with a coating thickness of 40-80 μm; 2-2. The carbon fiber insulation material after coating with the first coating adhesive is dried at 60-70℃ for 2-3 hours, then heated to 140-160℃ for 2-4 hours, and then carbonized at 600-900℃ to obtain a first transition coating with a thickness of 40-80μm.

6. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, In step 3), the preparation process of coating adhesive II is as follows: first, carbon fiber powder, silicon carbide fine powder and silicon fine powder are mixed and then water is added and stirred evenly. Then, dispersant and resin are added and mixed evenly. Finally, crosslinking agent is added and mixed for 4-6 hours to obtain coating adhesive II.

7. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, The specific process of step 3) is as follows: 3-1. Apply coating adhesive 2 evenly to the surface of the first transition coating, with a coating thickness of 10-40 μm; 3-2. The carbon fiber insulation material after coating with the second coating adhesive is dried at 60-70℃ for 2-3 hours, then heated to 140-160℃ for 2-4 hours, and then carbonized at 600-900℃ to obtain a second transition coating with a thickness of 10-40μm; then graphitization is carried out at 1600-2200℃ to allow carbon and silicon to fully react and generate silicon carbide.

8. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, In steps 1) to 3), the resin is one or more of epoxy resin, polybutadiene resin, phenolic resin, unsaturated polyester resin, polyurethane resin, and furan resin; the crosslinking agent is one or more of dicumyl peroxide, dicumyl peroxide, diethylenetriamine, polyisocyanate, alkyl isocyanate, glycidyl ether, phthalic anhydride, and tetrachlorophthalic anhydride; and the dispersant is one or more of gelatin, starch, polyvinyl alcohol, and polyether.

9. The method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, The specific process of step 4) is as follows: 4-1. Place the carbon fiber insulation material treated in step 3) into a chemical vapor deposition furnace; 4-2. A mixture of nitrogen and methane, propane or propylene is introduced into the furnace at a flow rate ratio of 3 to 10:1 and a pressure of 50 to 2000 Pa. 4-3. The chemical vapor deposition furnace is heated to 900-1100℃ at a heating rate of 1-10℃ / min, and the deposition is carried out for 10-30 hours. The depth of penetration into the first and second transition coatings is 50-120μm. Then, a vapor-deposited carbon coating with a thickness of 1-10μm is deposited on the surface of the second transition coating, and the mixture is naturally cooled to room temperature.

10. A method for preparing a high-performance silicon carbide coating on the surface of carbon fiber insulation material according to claim 1, characterized in that, The specific process of step 5) is as follows: 5-1. Place the carbon fiber insulation material treated in step 4) into a silicon carbide chemical vapor deposition furnace; 5-2. A mixture of nitrogen, methane, propane, propylene, silane, dichlorosilane, or trichlorosilane is introduced into the furnace at a flow rate ratio of 3–9:1:1; or a mixture of nitrogen and hexamethyldisilane is introduced at a flow rate ratio of 3–9:1; the pressure of the mixed gas is 200–3000 Pa. 5-3. The silicon carbide chemical vapor deposition furnace is heated to 800-1500℃ at a heating rate of 1-10℃ / min, and the deposition is carried out for 20-50h, controlling the penetration depth of the silicon carbide deposition coating to be 1-10μm; then a silicon carbide vapor deposition coating with a thickness of 10-70μm is deposited on the surface of the silicon carbide deposition coating, and the coating is naturally cooled to room temperature.

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