Preparation method of surface toughened silicon carbide coating of inorganic nonmetallic material

Abstract

This invention discloses a method for preparing a toughened silicon carbide coating on the surface of inorganic non-metallic materials, belonging to the field of inorganic non-metallic coating technology. The preparation method includes the following steps: first, SiC nanowires are deposited on the surface of an inorganic non-metallic substrate using chemical vapor deposition (CVD); then, a water-based slurry of hydroxylated modified α-SiC powder is prepared; next, the water-based slurry is sprayed onto the substrate surface using a cold spraying method; finally, CVD is performed to densify the coating. This invention is suitable for the large-scale batch preparation of coatings for irregularly shaped inorganic non-metallic products. The process is simple, the cycle is short, the cost is low, and the energy consumption is low. The obtained silicon carbide coating has good high-temperature resistance, oxidation resistance, corrosion resistance, and thermal shock resistance. The bonding strength between the coating and the carbon-based material can reach over 30 MPa, solving the problems of high oxidation sensitivity, easy cracking, high moisture sensitivity, and insufficient protective stability under thermal cycling in existing silicon carbide coatings.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic coating technology, and specifically to a method for preparing a toughened silicon carbide coating on the surface of inorganic non-metallic materials. Background Technology

[0002] Carbon-based materials (including carbon / carbon composites and graphite) have become an important material choice for advanced thermal equipment due to their excellent refractoriness, high specific strength / specific modulus, wear resistance, and thermal shock resistance even at high temperatures. Carbon / carbon composites, composed of carbon fiber-reinforced carbon matrix, combine strength retention and toughness at high temperatures, making them suitable for extreme thermal environments. Their commercial applications have expanded from aerospace to industrial fields, such as furnace fixtures, thermal insulation / shielding, support plates, and heating elements. Graphite, with its high electrical conductivity, low thermal expansion, and good thermal shock resistance, is suitable for use as heating electrodes, heating elements, and thermal field components in vacuum / inert atmosphere furnaces. In the hot zone of a vacuum furnace, graphite thermal fields can operate at approximately 2500~3000℃ under high vacuum conditions, meeting the requirements of high-temperature heat treatment, sintering, and crystal growth processes.

[0003] However, the aforementioned advantages rely on environmental control and surface protection. In oxygen-containing environments, carbon materials undergo rapid oxidation starting at approximately 400°C, leading to mass loss and mechanical degradation, significantly limiting the operating temperature window of the bare material in air. For graphite, engineering practice similarly shows that a significant oxidation risk begins to appear when the temperature exceeds approximately 400-500°C. Therefore, industrial applications often employ anti-oxidation coatings such as SiC and Si3N4, or multilayer protective systems. However, due to the mismatch in thermal expansion between the coating and the carbon matrix, cracks easily form at lower temperatures (e.g., below the coating temperature, typically <1250°C), creating oxygen penetration channels. At higher temperatures or under low oxygen partial pressure conditions, SiC will fail due to active oxidation in dry atmospheres at approximately ≥1800°C. While borosilicate glass coatings can form a dense glassy phase to block oxygen at medium to low temperatures, they are sensitive to moisture and easily volatilize at rising temperatures, leading to coating peeling and reduced lifespan under humid or cyclic operating conditions. In vacuum / inert atmosphere heat treatment equipment, while graphite hot zones and heating elements can significantly improve the upper temperature limit and energy efficiency, oxygen exposure and thermal cycling still need to be strictly controlled during start-up, shutdown, door opening maintenance, and accidental air intake to avoid component oxidation and performance degradation, which would affect furnace reliability and maintenance costs. In summary, carbon / carbon composites and graphite materials have been widely used in high-temperature hot zones and furnace components, but oxidation sensitivity, coating cracking and moisture-induced degradation, and protective stability under thermal cycling constitute key bottlenecks for their long-term service. There is an urgent need for efficient oxidation resistance, long-life protection, and structural design solutions for industrial applications.

[0004] Patent CN121063960A discloses a method for bonding a chemical vapor deposition (CVD) SiC coating to the surface of graphite parts modified with a silazane and boron-silicon carametite composite. This method significantly improves the coating's density, uniformity, and adhesion to the substrate by introducing boron, silicon, and nitrogen. However, the low-melting-point boron-silicon system in this method reduces the coating's reliability at higher temperatures. Patent CN120622958A discloses a method for coating a C / C composite material with a ZrC-SiC coating. This method requires only one high-temperature heat treatment, significantly reducing damage to the C / C composite material compared to multiple high-temperature heat treatments, and shortening the testing cycle. However, this method faces the problem of excessively high costs for refractory metal precursors. Patent CN120905642A discloses a method for preparing a CVD SiC coating on a graphite surface. This coating contains a large number of submicron porous SiC transition layers and a dense β-SiC main coating. Through structural design and preparation, the service life of CVD SiC-coated graphite products is improved. While the porous transition layer design can alleviate the problem of thermal expansion mismatch, these pores can create oxygen infiltration pathways during thermal cycling. CN202510959080.1 discloses a method for preparing a gradient transition Si / SiC coating on a graphite substrate surface using plasma spraying combined with vacuum heat treatment. This solves the problem that traditional plasma-sprayed Si coatings on graphite surfaces cannot operate at 1500℃. However, plasma spraying technology is costly and cannot meet the low-cost requirements of industry. CN120664905A discloses a method for obtaining a single-phase medium-entropy boride ceramic by ball milling and mixing TiO2, ZrO2, and Ta2O5 metal oxide powders, B4C, and C powders, followed by two vacuum heat treatments. This ceramic is then used as a modifier and mixed with Si and SiC, followed by discharge plasma sintering to obtain a graphite-based (TiO2 / ZrO2 / Ta2O5) ceramic. 1 / 3 Zr 1 / 3 Ta 1 / 3 B2-Si-SiC ceramic coating material. However, this method suffers from problems such as high raw material costs, high spark plasma sintering costs, and difficulties in industrial application. Patent CN202510321035.3 discloses a SiC coating on the surface of carbon / carbon composite material and its laser deposition method. In this method, Si-SiC composite powder is used as the deposition powder, and a SiC coating is formed on the carbon-carbon surface by laser cladding. This significantly improves the overall density and uniformity of the coating, and makes the coating and the substrate form a better metallurgical bond. However, the laser deposition method is difficult to form a continuous SiC coating on the surface of complex structural parts. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a method for preparing a toughened silicon carbide coating on the surface of inorganic non-metallic materials, thereby solving the problems of high oxidation sensitivity, easy cracking, high sensitivity to moisture, and insufficient protective stability under thermal cycling in existing toughened silicon carbide coatings on the surface of inorganic non-metallic materials.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material, comprising the following steps: In-situ deposition of SiC nanowires: First, the inorganic non-metallic substrate is immersed in a catalyst solution, and then SiC nanowires are deposited to obtain an inorganic non-metallic substrate with SiC nanowires deposited in situ on the surface. S2, Preparation of water-based SiC slurry: A water-based slurry was prepared using hydroxylated modified α-SiC powder as raw material. S3. Preparation of composite coating: Using the water-based slurry obtained from S2 as raw material, SiC nanowires were deposited in situ on the surface of an inorganic non-metallic substrate obtained from S1 and then cold-sprayed and dried to obtain an inorganic non-metallic substrate with a composite coating. S4. Coating densification: CVD deposition was performed on the inorganic non-metallic substrate with the composite coating obtained in S3 to obtain a toughened silicon carbide coating on the surface of the inorganic non-metallic material.

[0007] The beneficial effects of this invention are as follows: This invention utilizes the synergistic effect of a single-crystal SiC nanonetwork formed in situ on the substrate surface and the toughening and reinforcing effect of hydroxylated modified α-SiC particles to prepare a SiC nanowire-SiC nanoparticle toughened SiC coating on the surface of inorganic non-metallic materials. This significantly improves the bonding force between the substrate and the coating, and greatly enhances the overall density, purity, and uniformity of the coating, thereby improving the reliability of the coating.

[0008] Furthermore, inorganic non-metallic substrates include carbon-based substrates.

[0009] Furthermore, in S1, the inorganic non-metallic substrate is polished and cleaned before impregnation.

[0010] Furthermore, the inorganic non-metallic substrate was polished using 200, 400 and 600 grit water-resistant sandpaper in sequence, employing a cross-grit sanding method.

[0011] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the present invention removes impurities from the surface of the substrate material by polishing, and increases the roughness of the substrate surface on the other hand.

[0012] Furthermore, the cleaning method is as follows: First, clean the polished substrate with distilled water, wipe the surface of the substrate with alcohol cotton, and after air drying, place the substrate in NaOH solution and treat it in an 80°C water bath for 30 minutes; then cool it to room temperature, take out the substrate and rinse it with distilled water until neutral; finally, ultrasonically clean the substrate in acetone for 5 minutes to complete the cleaning.

[0013] Furthermore, the catalyst in S1 includes at least one of nickel chloride, cobalt chloride, ferric chloride and copper chloride, or at least one of nickel nitrate, cobalt nitrate, ferric nitrate and copper nitrate; The catalyst solution has a mass concentration of 1% to 5% and a pH of 3 to 4.

[0014] Furthermore, the pH is adjusted using hydrochloric acid or acetic acid.

[0015] Furthermore, the solvent for the catalyst solution is anhydrous ethanol or deionized water.

[0016] Furthermore, the conditions for SiC nanowire deposition in S1 are as follows: the flow rate of bubbling hydrogen is 1~5 L / min, the flow rate of dilution hydrogen is 1~5 L / min, the flow rate of dilution argon is 1~10 L / min, the heat treatment temperature is 900~1200℃, and the time is 0.5~5.5 h.

[0017] Furthermore, the hydroxylated modified α-SiC powder in S2 was prepared by the following method: First, α-SiC powder is mixed with a mixed solution of HCl and HF to obtain a uniform slurry. Then, it is ball-milled, washed, dried, and finally calcined to obtain hydroxylated modified α-SiC powder.

[0018] Furthermore, the particle size of the α-SiC powder is 0.5~3 μm; The mass concentration of HCl in the mixed solution is 10%~20%, and the mass concentration of HF is 10%~20%. The ball milling process was carried out at a speed of 50-100 rpm for 24-48 hours. The calcination treatment temperature is 500~700℃, and the time is 1~3 h.

[0019] Further, the washing process was carried out by adding deionized water to dilute the slurry, sieving to remove unacceptable particles, and then using repeated washing to replace the HCl and HF acids in the slurry, repeating the process five times.

[0020] Furthermore, the mass concentration of hydroxylated modified α-SiC powder in the water-based slurry of S2 is 30%~50%.

[0021] Furthermore, the water-based slurry also includes polyacrylate, polyacrylic acid latex and polyethylene glycol diamine, or PVA, PEG-400 and polyethylene glycol P1200, or tetramethylammonium hydroxide, PEG-400, acrylamide and methylenebisacrylamide.

[0022] Furthermore, when the water-based slurry uses a system containing tetramethylammonium hydroxide, PEG-400, acrylamide and methylenebisacrylamide, the water-based slurry is sprayed first during S3 cold spraying, followed by the ammonium persulfate solution.

[0023] Furthermore, the mass concentration of the ammonium persulfate solution is 5% to 20%.

[0024] Furthermore, in S3, the nozzle diameter of the cold spray gun is 0.3~1.2 mm, the spraying distance is 20~50 cm, and the spraying rate is 0.1~2 mL / min; The drying temperature is 40~100℃ and the time is 15~120 min.

[0025] Furthermore, the CVD deposition conditions in S4 are as follows: the flow rate of bubbling hydrogen is 1~5 L / min, the flow rate of dilution hydrogen is 1~5 L / min, the flow rate of dilution argon is 1~10 L / min, the heat treatment temperature is 900~1200℃, and the time is 10~20h.

[0026] In a second aspect, the present invention provides a toughened silicon carbide coating for the surface of an inorganic non-metallic material, which is prepared by the above-described preparation method.

[0027] The present invention has the following beneficial effects: 1. This invention provides a method for preparing a toughened silicon carbide coating on the surface of inorganic non-metallic materials. It is suitable for the large-scale batch preparation of coatings on irregularly shaped inorganic non-metallic products. The preparation process is simple, the preparation cycle is short, the raw material cost is low, and the equipment energy consumption is low.

[0028] 2. The silicon carbide coating prepared by this invention has good high temperature resistance, oxidation resistance, corrosion resistance and thermal shock resistance. The bonding strength between the coating and the carbon-based material can reach more than 30 MPa, and it can be applied to a variety of high temperature industrial and chemical scenarios. Attached Figure Description

[0029] Figure 1 A schematic diagram of the preparation process of a toughened silicon carbide coating on the surface of inorganic non-metallic materials; Figure 2 A photograph of a toughened silicon carbide coating on the surface of an inorganic non-metallic material. Figure 3The morphology of SiC nanowires deposited in situ on the substrate surface is shown in Figures 1 and 2. In Figures 1 and 2, a and b represent the morphology of SiC nanowires deposited in situ on the graphite substrate surface, and c and d represent the morphology of SiC nanowires deposited in situ on the carbon / carbon composite substrate surface. Detailed Implementation

[0030] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0031] Example 1: A method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material (preparation flow chart as shown) Figure 1 (As shown), including the following steps: S1. Substrate surface pretreatment: In this embodiment, a carbon-based substrate (graphite substrate) is used as the inorganic non-metallic material. First, the substrate is sanded sequentially using 200, 400, and 600 grit water-resistant sandpaper, employing a cross-grit sanding method to increase the surface roughness. The sanded carbon-based substrate is then cleaned in distilled water, wiped with an alcohol swab, and dried with a hair dryer. Next, the substrate is immersed in a pre-prepared 5% NaOH solution and treated in an 80°C constant temperature water bath for 30 minutes. After treatment, it is cooled to room temperature, removed, and rinsed with distilled water until neutral. The cleaned carbon-based substrate is then placed in a beaker containing acetone and ultrasonically cleaned for 5 minutes to further remove oil and clean the substrate. The cleaned substrate is then dried with a hair dryer and stored in ethanol.

[0032] S2. In-situ deposition of SiC nanowires on carbon-based substrates: First, a catalyst solution with a mass concentration of 3% was prepared using nickel chloride as the solute and anhydrous ethanol as the solvent. The pH was adjusted to between 3 and 4 using HCl, and the solution was dried for later use. Then, the carbon-based substrate was immersed in the catalyst solution and vacuum impregnated for 40 min to obtain the catalyst-treated carbon-based material. Finally, the catalyst-treated carbon-based material was placed in a crucible, and the crucible was placed in a deposition furnace for deposition. The flow rates of H2 bubbling, diluted H2, and diluted Ar were 3 L / min, and the heat treatment temperature was 1000℃ for 3 h to obtain a carbon-based substrate with SiC nanowires deposited on the surface.

[0033] S3. Preparation of water-based slurry: Preparation of S301 and α-SiC-OH powders: α-SiC powder with a particle size of 0.5~3 μm and a purity ≥99% was screened out and then mixed with a mixed solution of HCl and HF (HCl mass concentration 15%, HF mass concentration 15%) to prepare a homogeneous slurry. The slurry was then placed in a ball mill and ball-milled at 80 rpm for 36 h. Next, deionized water was added to dilute the slurry, and then unqualified particles were removed by sieving. The slurry was then repeatedly washed to replace the HCl and HF acids in the slurry. The above steps were repeated 5 times. Finally, the slurry was dried to obtain pure α-SiC powder, which was then calcined at 600℃ for 2 h to obtain α-SiC-OH powder.

[0034] S302, Preparation of water-based slurry: First, α-SiC-OH powder was mixed with deionized water and polyacrylate, wherein the mass content of α-SiC-OH powder was 70% and the mass content of polyacrylate was 0.5%. After mixing, the mixture was ball-milled at 90 rpm for 36 h to obtain solution I. Then, polyacrylic acid latex and polyethylene glycol diamine were mixed at a mass ratio of 16:0.18 to obtain solution II. Finally, solution II was added to solution I (the volume ratio of solution II to solution I was 1:1), and the mixture was ball-milled and dispersed for 12 h before being sieved through a 100-mesh sieve to obtain a water-based slurry.

[0035] S4. Preparation of composite coating A water-based slurry was cold-sprayed onto the surface of a carbon-based substrate on which SiC nanowires were deposited in situ using a spray gun. The spray gun nozzle diameter was 0.6 mm, the spraying distance was 35 cm, and the spraying rate was 1 mL / min. The substrate was then dried in an oven at 70°C for 60 min to obtain a carbon-based substrate with a composite coating.

[0036] S5, Coating Densification A carbon-based substrate with a composite coating was placed in a deposition furnace for deposition. The flow rates of bubbling H2 were 3 L / min, diluted H2 were 3 L / min, and diluted Ar were 5 L / min. The heat treatment temperature was 1000℃, and the heat treatment time was 15 h, resulting in a toughened silicon carbide coating on the surface of an inorganic non-metallic material (e.g., ...). Figure 2 (As shown).

[0037] Example 2: A method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material. In this embodiment, the preparation method of the silicon carbide coating is the same as that in Example 1, except that the preparation process of the water-based slurry in S302 is different. In this embodiment, S302 specifically includes the following steps: First, the dried α-SiC-OH powder was mixed with deionized water, with the α-SiC-OH powder content being 60% by mass. After mixing, the mixture was ball-milled at 90 rpm for 36 h to obtain solution I. Then, PVA, deionized water, PEG-400, and polyethylene glycol P1200 were mixed in a mass ratio of 6:9.5:1.5:0.5 and stirred for 30 min to obtain solution II. Finally, solution II was added to solution I (the volume ratio of solution II to solution I was 1:1), ball-milled and dispersed for 12 h, and then sieved through a 100-mesh sieve to obtain a water-based slurry.

[0038] Example 3: A method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material. In this embodiment, the preparation method of the silicon carbide coating is the same as that in Example 1, except that the preparation process of the water-based slurry in S302 and the preparation process of the composite coating in S4 are different. In this embodiment, S302 specifically includes the following steps: First, tetramethylammonium hydroxide was added to deionized water to adjust the pH of the solution to about 11. Then, 40% by mass of α-SiC-OH powder was added, followed by 1.5% by mass of PEG-400. After ball milling for 36 h, 15% by mass of acrylamide and 0.5% by mass of methylenebisacrylamide were added, and ball milling was continued for 4.5 h to obtain solution I. Then, ammonium persulfate was mixed with deionized water and stirred for 20 min to prepare solution II with a mass concentration of 10%.

[0039] In this embodiment, solutions I and II are used independently as spraying slurries for cold spraying. First, solution I is cold sprayed onto the surface of a carbon-based substrate with in-situ deposited SiC nanowires. Then, solution II is cold sprayed onto the same surface. The substrate is cured and dried at 60°C for 60 minutes to obtain a carbon-based substrate with a composite coating. The cold spraying conditions in this embodiment are the same as in Example 1.

[0040] Example 4: A method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material. In this embodiment, the preparation method of the silicon carbide coating is the same as in Example 1, except that the heat treatment temperature in S5 is changed to 1100℃, while the other steps remain unchanged.

[0041] Comparative Example 1: A method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material. The difference between this comparative example and Example 1 is that water-based SiC coating composite is not performed, and only the process flow of S1, S2 and S5 is performed.

[0042] Comparative Example 2: A method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material. The difference between this comparative example and Example 1 is that SiC nanowire composite is not performed, but only the S1, S3, S4 and S5 process steps are performed.

[0043] Experimental example: The surface microstructure of the carbon-based substrate with in-situ deposited SiC nanowires and the carbon-carbon composite material with toughened silicon carbide coating prepared in Example 1 were characterized.

[0044] The hardness, adhesion, and thermal cycling performance of the silicon carbide coatings prepared in Examples 1-4 and Comparative Examples 1-2 were characterized. The coating hardness was tested according to the method specified in GB / T 16534-2009; the coating adhesion was tested according to the method specified in GB / T 39685-2020; the thermal cycling performance was tested by heating from room temperature to 1000℃ for 2 hours in air environment for a heating time of <30 min, then removing it and allowing it to cool naturally at room temperature, and cycling 30 times, and then calculating the oxidation weight loss rate.

[0045] Experimental results are as follows Figure 3 As shown in Table 1.

[0046] Table 1 Performance Results

[0047] like Figure 3 As shown, based on the surface microstructure of the carbon-based substrate with in-situ deposited SiC nanowires, it can be seen that the present invention successfully generated SiC nanowires in-situ on the surface of the carbon-based substrate. Based on the surface microstructure of the carbon-carbon composite material with toughened silicon carbide coating, it can be seen that the silicon carbide coating prepared by the present invention achieves effective combination of SiC nanowires and α-SiC-OH powder, indicating the successful preparation of the toughened silicon carbide coating of the present invention.

[0048] As shown in Table 1, the SiC coatings prepared using only single SiC reinforcement (Comparative Examples 1-2) have significantly lower bonding strength and hardness than those in Examples 1-4 of this application, and significantly higher thermal cycling oxidation weight loss rate than those in Examples 1-4 of this application. The results show that the present invention achieves a significant improvement in the bonding strength, hardness, and thermal cycling performance of silicon carbide coatings through the synergistic effect of the single-crystal SiC nanonetwork formed in situ on the substrate surface and the toughening and reinforcement by hydroxylated modified α-SiC particles, thus significantly improving the overall performance of silicon carbide coatings. Among them, the silicon carbide coating prepared in Example 3 is the embodiment with the best overall performance in this application.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material, characterized in that, Includes the following steps: In-situ deposition of SiC nanowires: First, the inorganic non-metallic substrate is immersed in a catalyst solution, and then SiC nanowires are deposited to obtain an inorganic non-metallic substrate with SiC nanowires deposited in situ on the surface. S2, Preparation of water-based SiC slurry: A water-based slurry was prepared using hydroxylated modified α-SiC powder as raw material. S3. Preparation of composite coating: Using the water-based slurry obtained from S2 as raw material, SiC nanowires were deposited in situ on the surface of an inorganic non-metallic substrate obtained from S1 and then cold-sprayed and dried to obtain an inorganic non-metallic substrate with a composite coating. S4. Coating densification: CVD deposition was performed on the inorganic non-metallic substrate with the composite coating obtained in S3 to obtain a toughened silicon carbide coating on the surface of the inorganic non-metallic material.

2. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 1, characterized in that, In step S1, the inorganic non-metallic substrate is polished and cleaned before impregnation.

3. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 1, characterized in that, The catalyst in S1 includes at least one of nickel chloride, cobalt chloride, ferric chloride and copper chloride, or at least one of nickel nitrate, cobalt nitrate, ferric nitrate and copper nitrate. The catalyst solution has a mass concentration of 1% to 5% and a pH of 3 to 4.

4. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 1, characterized in that, The conditions for SiC nanowire deposition in S1 are as follows: the flow rate of bubbling hydrogen is 1~5 L / min, the flow rate of dilution hydrogen is 1~5 L / min, the flow rate of dilution argon is 1~10 L / min, the heat treatment temperature is 900~1200℃, and the time is 0.5~5.5 h.

5. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 1, characterized in that, The hydroxylated modified α-SiC powder in S2 is prepared by the following method: First, α-SiC powder is mixed with a mixed solution of HCl and HF to obtain a uniform slurry. Then, it is ball-milled, washed, dried, and finally calcined to obtain hydroxylated modified α-SiC powder.

6. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 5, characterized in that, The particle size of the α-SiC powder is 0.5~3 μm; The mass concentration of HCl in the mixed solution is 10%~20%, and the mass concentration of HF is 10%~20%. The ball milling process is performed at a speed of 50-100 rpm for a duration of 24-48 h. The calcination treatment is carried out at a temperature of 500~700℃ for 1~3 hours.

7. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 1, characterized in that, The mass concentration of hydroxylated modified α-SiC powder in the water-based slurry of S2 is 30%~50%.

8. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 1, characterized in that, The nozzle diameter of the spray gun in S3 for cold spraying is 0.3~1.2 mm, the spraying distance is 20~50 cm, and the spraying rate is 0.1~2 mL / min; The drying temperature is 40~100℃ and the time is 15~120 min.

9. The method for preparing a toughened silicon carbide coating on the surface of an inorganic non-metallic material according to claim 1, characterized in that, The CVD deposition conditions in S4 are as follows: the flow rate of bubbling hydrogen is 1~5 L / min, the flow rate of dilution hydrogen is 1~5 L / min, the flow rate of dilution argon is 1~10 L / min, the heat treatment temperature is 900~1200℃, and the time is 10~20 h.

10. A toughened silicon carbide coating on the surface of an inorganic non-metallic material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 9.

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