Glassy carbon in-situ reaction SiC-based coating, preparation method and application

Abstract

The invention relates to the technical field of preparation of C / C composite coatings, in particular to a glassy carbon in-situ reaction SiC-based coating and a preparation method and application thereof.The method comprises the steps that glassy carbon powder is prepared from a carbon-containing precursor, the prepared glassy carbon powder serves as a supplementary carbon source, and mixed slurry is prepared from the supplementary carbon source and mixed ceramic powder; finally, a SiC-based coating preform is prefabricated and sequentially subjected to carbonization treatment and siliconizing treatment, glassy carbon serves as a supplementary carbon source to be subjected to an in-situ reaction with free silicon to generate SiC, and therefore the content of residual silicon is reduced, meanwhile, the compactness of the coating is improved, the internal structure and high-temperature oxidation resistance of the C / C composite material are improved, and the performance of the composite material is improved. The material is more stable in performance and longer in service life in a high-temperature environment, the glassy carbon is low in cost, simple and convenient to prepare and remarkable in economic advantage, and the problem that a C / C composite coating is poor in high-temperature stability in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of C / C composite coating preparation, in particular to a glassy carbon in-situ reaction SiC-based coating, a preparation method and application. BACKGROUND

[0002] Carbon / carbon (C / C) composite material refers to a composite material made of carbon fiber and its fabric as reinforcing material and carbon (or graphite) as matrix through densification and graphitization treatment, which has excellent properties such as high specific strength, high specific modulus, low thermal expansion coefficient, high temperature resistance, etc., so that it is widely used in aircraft hot end components, friction materials and nuclear energy fields. However, C / C composite material is easily oxidized in oxygen environment above 370℃. The oxidation of C / C composite material starts from the reaction of surface active sites with oxygen to form CO or CO2 gas, resulting in material mass loss and porosity increase. With the deepening of oxidation, oxygen diffuses to the inside through the pores, causing deep oxidation of the matrix carbon, and ultimately leading to the collapse of the mechanical properties of the material, a sharp decline in mechanical properties, and even causing structural failure, which limits its application in aerospace and other fields. At present, the main means to solve this oxidation sensitivity problem includes using embedding, thermal spraying, chemical vapor deposition, slurry brushing, gas / liquid silicon infiltration, etc. to prepare high-temperature oxidation-resistant coating to resist the diffusion of oxygen to the inside of C / C composite material. Among them, slurry brushing refers to mixing ceramic powder with organic binder to form slurry, which is brushed on the surface of the material, and then dried and high-temperature treated to form a coating. Silicon infiltration technology is a chemical heat treatment process that infiltrates silicon into the surface layer of the workpiece, aiming to improve the corrosion resistance, wear resistance, hardness and oxidation resistance of the material. The existing slurry brushing often combines with silicon infiltration technology, which has the advantages of short preparation cycle, strong designability of coating composition and structure, etc., and is often applied to the preparation of high-temperature oxidation-resistant coating on the surface of C / C composite material.

[0003] However, silicon infiltration often leads to a large amount of residual silicon, causing a large number of structural defects, damaging the internal structure of C / C composite material and high-temperature oxidation resistance. For example, in the document "Zhang Pei, Cheng Chunyu, Liu Bing, et al. Multicomponent (Hf 0.25 Zr 0.25 Ti 0.25 Cr 0.25)B2ceramic modified SiC-Si compositecoatings: In-situ synthesis and high-temperature oxidation behavior[J].CERAMICS INTERNATIONAL,2022,48,(9):12608-12624.”XRD analysis shows that there is a significant amount of residual Si in the coating. In a high-temperature environment, Si is activated and generates volatile SiO and CO2 / CO gaseous products, which accumulate inside the coating and produce high pressure, causing the oxidation film to crack, and in turn forming structural defects such as pores and cracks, ultimately severely damaging the high-temperature oxidation resistance performance of the coating. SUMMARY

[0004] In view of the poor high-temperature stability of the C / C composite material coating in the prior art, the present application provides a glassy carbon in-situ reaction SiC-based coating, a preparation method and an application.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: The present application provides a preparation method of a glassy carbon in-situ reaction SiC-based coating, comprising: preparing glassy carbon powder using carbon-containing precursors; preparing mixed slurry using glassy carbon powder and mixed ceramic powder; the mixed ceramic powder is a mixed ceramic powder containing SiC powder; preparing SiC-based coating preform using mixed slurry; carrying out carbonization treatment and silicon infiltration treatment on the SiC-based coating preform in sequence to obtain SiC-based coating.

[0006] Optionally, the carbon-containing precursor is phenolic resin or polyvinyl alcohol.

[0007] Optionally, the method for preparing glassy carbon powder using carbon-containing precursors is: pyrolyzing the carbon-containing precursors at 800-1100℃ to convert them into glassy carbon; processing the glassy carbon into micron-sized powder with a particle size of 5-30µm to obtain glassy carbon powder.

[0008] Optionally, the ceramic powder further comprises one or more of HfB2, HfC, MoSi2, ZrSi2 and TaSi2.

[0009] Optionally, the method for preparing mixed slurry using glassy carbon powder and ceramic powder is: Mix 15-25% glass carbon powder and 75-85% ceramic powder by mass percentage and disperse in a phenolic resin anhydrous ethanol solution to obtain a mixed slurry; wherein the concentration of the phenolic resin in the phenolic resin anhydrous ethanol solution is 10-15 wt%.

[0010] Optionally, the mass ratio of SiC powder to other ceramic powder in the mixed ceramic powder is (50-70):(30-50).

[0011] Optionally, the carbonization treatment condition is an argon atmosphere, and the carbonization treatment temperature is 800-1100 DEG C.

[0012] Optionally, the silicon infiltration treatment method is as follows: bury the SiC-based coating preform after carbonization treatment in silicon powder, heat to 1400-1450 DEG C at a rate of 3.5-10 DEG C / min under vacuum, and keep the temperature for 1-3 h to complete the silicon infiltration treatment.

[0013] The application also provides a glass carbon in-situ reaction SiC-based coating prepared by the above method.

[0014] The above glass carbon in-situ reaction SiC-based coating or the above method for preparing the glass carbon in-situ reaction SiC-based coating is applied to the preparation of a C / C composite material component or an aerospace device.

[0015] Compared with the prior art, the application has the following beneficial effects: The application provides a method for preparing a glass carbon in-situ reaction SiC-based coating, which comprises the following steps: preparing glass carbon powder by using a carbon-containing precursor, preparing a mixed slurry by using the prepared glass carbon powder as a supplementary carbon source and mixed ceramic powder, and finally performing carbonization treatment and silicon infiltration treatment on a SiC-based coating preform in sequence, so that the glass carbon reacts with free silicon in-situ to generate SiC as a supplementary carbon source, thereby reducing the residual content of free silicon, avoiding the generation of active oxidation and volatile gaseous products caused by free silicon, improving the coating density, and further improving the internal structure of the C / C composite material and high-temperature oxidation resistance, so that the material has more stable performance and longer service life in a high-temperature environment. The method realizes precise regulation of the coating composition, has the characteristics of simple preparation process, short preparation period and high production efficiency, greatly reduces the production cost while ensuring the performance, and provides a reliable solution for the industrial application of high-performance silicon infiltration coating.

[0016] The carbon-containing precursor is phenolic resin or polyvinyl alcohol, and the carbonized phenolic resin or carbonized polyvinyl alcohol is a porous amorphous glassy carbon, which has a higher reactivity than crystalline carbon, can achieve a more complete SiC conversion at a lower temperature, reduces the requirement for high-temperature resistance of the equipment, reduces energy consumption, and improves the conversion rate of the reaction and the quality stability of the product. Moreover, the carbon-containing precursors such as phenolic resin and polyvinyl alcohol have a low price, and have obvious advantages in cost control.

[0017] The method for preparing the glassy carbon powder by using the carbon-containing precursor comprises the following steps: pyrolyzing the carbon-containing precursor at 800-1100 DEG C to convert it into glassy carbon; and processing the glassy carbon into micron-sized powder with a particle size of 5-30 µm to obtain the glassy carbon powder. The glassy carbon preparation method is simple and short in cycle, and meets the requirements of modern industry for high efficiency and sustainable production. In the process of large-scale industrial production, the preparation of the glassy carbon can be solved in one furnace together with the carbonization of the coating sample, which is more cost-saving.

[0018] The ceramic powder further comprises one or more of HfB2, HfC, MoSi2, ZrSi2 and TaSi2. The addition of different ceramic powders can endow the coating with different properties, such as higher hardness, better wear resistance or more excellent oxidation resistance, etc., to meet the diversified requirements of different application scenarios for the performance of the coating.

[0019] The application provides a glassy carbon in-situ reaction SiC-based coating prepared by the above-mentioned preparation method of the glassy carbon in-situ reaction SiC-based coating. The glassy carbon in-situ reaction SiC-based coating generates SiC by in-situ reaction of glassy carbon as a supplementary carbon source and free silicon. SiC has excellent high-temperature stability and oxidation resistance, and can effectively prevent oxygen from further penetrating into the C / C composite material. Therefore, the glassy carbon in-situ reaction SiC-based coating has better high-temperature oxidation resistance, and thus has a longer service life. At the same time, the in-situ generated SiC is closely combined with the surrounding material, can fill the pores and defects in the coating, makes the coating structure more dense, and further improves the performance of the coating, so that the coating reaches the best balance in hardness, wear resistance, oxidation resistance and the like.

[0020] The above-mentioned glassy carbon in-situ reaction SiC-based coating or the above-mentioned preparation method of the glassy carbon in-situ reaction SiC-based coating is applied to the preparation of a C / C composite material component or an aerospace device. Since the coating has more excellent high-temperature oxidation resistance, the prepared C / C composite material component or aerospace device can work stably under extremely high-temperature conditions. The coating can effectively prevent oxygen from contacting the C / C composite material, reduce oxidation damage, reduce the mass loss and performance attenuation of the material due to oxidation, and thus significantly prolong the service life of the C / C composite material component and the aerospace device. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A flow chart of a preparation method of a glassy carbon in-situ reacted SiC-based coating according to the present application.

[0022] Figure 2 A flow chart of a preparation process of a glassy carbon in-situ reacted SiC-based coating according to the present application.

[0023] Figure 3 A test result graph of the glassy carbon prepared in Example 1 of the present application, wherein a is a microstructure graph of the glassy carbon A, b is an XRD pattern of the glassy carbon A, and c is a grain size distribution graph of the glassy carbon A. Figure 4 A test result graph of the glassy carbon in-situ reacted SiC-based high-temperature coating prepared in Example 1 of the present application, wherein a is an XRD pattern of the glassy carbon in-situ reacted SiC-based high-temperature coating, b is a cross-section microstructure graph of the glassy carbon in-situ reacted SiC-based high-temperature coating, and c is a surface microstructure graph of the glassy carbon in-situ reacted SiC-based high-temperature coating.

[0024] Figure 5 A test result graph of the high-temperature coating prepared in Comparative Example 1 of the present application, wherein a is an XRD pattern of the coating, b is a cross-section graph of the coating, and c is a surface graph of the coating.

[0025] Figure 6 A high-temperature coating prepared in Comparative Example 2 of the present application, wherein a is an XRD pattern of the coating, b is a cross-section graph of the coating, and c is a surface graph of the coating. Figure 7 A coating with excess phenolic resin in Comparative Example 3 of the present application, wherein a is a macroscopic photograph of the coating, and b is a surface of the coating. DETAILED DESCRIPTION

[0026] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings to those skilled in the art of the present application, and in the event of a conflict, the definitions in the present specification shall prevail.

[0027] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting of the scope of the present application, i.e., the present application can be practiced without regard to any particular theory or mechanism.

[0028] Herein, all features defined by a numerical range or a percentage range, such as numerical values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of a numerical range or a percentage range shall be deemed to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0029] Herein, unless otherwise specifically noted, "comprise", "comprising", "contain", "containing", "have", "having", or any other like terminology, are all meant to encompass the meaning of "consist of" and "consist essentially of", for example, "A comprises a" encompasses the meaning of "A comprises a and other" and "A comprises only a".

[0030] Herein, in order to make the description concise, all possible combinations of the technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of the technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope of the present specification.

[0031] The present application is further described in detail by the following specific examples. It is to be understood that these examples are intended to illustrate the application and are not to be construed as limiting the scope of the application. Furthermore, it is to be understood that various equivalents and modifications of the application can be made by those skilled in the art, after reading the description of the application, and that such equivalents and modifications are also intended to be encompassed by the scope of the appended claims.

[0032] In the following examples, the instruments and apparatuses used are those conventional in the art. In the following examples, the experimental methods not otherwise specified are usually carried out under the conventional conditions, or under the conditions recommended by the manufacturers. In the following examples, various raw materials are used, unless otherwise specified, and the conventional commercially available products are used, which are of the conventional specifications in the art. In the specification of the present application and in the following examples, unless otherwise specified, "%" means "percent by weight", "parts" means "parts by weight", and the ratio means "ratio by weight".

[0033] The present application is further described in detail by the following specific examples. It is to be understood that these examples are intended to illustrate the application and are not to be construed as limiting the scope of the application. Furthermore, it is to be understood that various equivalents and modifications of the application can be made by those skilled in the art, after reading the description of the application, and that such equivalents and modifications are also intended to be encompassed by the scope of the appended claims.

[0034] Referring to Figure 1 and Figure 2 The present application discloses a preparation method of a glass carbon in-situ reaction SiC-based coating, comprising: S1: preparing a glass carbon powder by using a carbon-containing precursor, specifically: pyrolyzing the carbon-containing precursor at 800-1100°C to convert it into glass carbon; in some preferred embodiments, the carbon-containing precursor is phenol formaldehyde resin or polyvinyl alcohol; treating the glass carbon into a micron-sized powder with a particle size of 5-30 µm to obtain the glass carbon powder.

[0035] S2: preparing a mixed slurry by using glass carbon powder and mixed ceramic powder, specifically: According to the mass percentage, 15% to 25% of glass carbon powder and 75% to 85% of ceramic powder are mixed and dispersed in a phenolic resin anhydrous ethanol solution to obtain a mixed slurry; wherein the concentration of phenolic resin in the phenolic resin anhydrous ethanol solution is 10wt% to 15wt%; the mixed ceramic powder is a mixed ceramic powder containing SiC powder, and the mass ratio of SiC powder to other ceramic powder in the mixed ceramic powder is (50-70):(30-50); in some optional embodiments, the ceramic powder can be selected according to the requirements of the coating performance; the mixed ceramic powder further includes one or more of HfB2, HfC, MoSi2, ZrSi2 and TaSi2.

[0036] S3: preparing a SiC-based coating preform by using the mixed slurry, specifically: The mixed slurry is brushed on the surface of the C / C composite material embedded with SiC coating, and after brushing one layer of slurry, drying is performed until the weight of the C / C composite material substrate with slurry increases by 15% to 25% of the original substrate weight, and the substrate with slurry is dried and solidified to obtain a SiC-based coating preform.

[0037] S4: sequentially performing carbonization treatment and silicon infiltration treatment on the SiC-based coating preform to obtain a SiC-based coating, specifically: The SiC-based coating preform is placed in an argon atmosphere at 800°C to 1100°C for carbonization treatment. The SiC-based coating preform after carbonization treatment is embedded in silicon powder, and under vacuum conditions, the temperature is raised to 1400°C to 1450°C at a rate of 3.5°C / min to 10°C / min, and the temperature is maintained for 1 to 3 hours to complete the silicon infiltration treatment, and a SiC-based coating is obtained.

[0038] Example 1 10g of phenolic resin is weighed and placed in an alumina crucible, which is placed in a tubular heat treatment furnace, and carbonized at 900°C for 2h in an argon protective atmosphere to obtain glass carbon, which is ground into 5-30µm micron-sized glass carbon powder using a mortar; the test result graph of the glass carbon shows that the glass carbon is carbonized phenolic resin. Figure 3

[0039] According to the mass percentage, 20% of glass carbon powder and 80% of mixed ceramic powder are mixed and added to a phenolic resin anhydrous ethanol solution with a concentration of 10wt%, and after being fully stirred for 5h under a magnetic stirrer, a mixed slurry is obtained; wherein the mixed ceramic powder includes SiC, HfB2 and MoSi2 powder, and the mass ratio is SiC:HfB2:MoSi2=5:4:1;​ The mixed slurry is uniformly brushed on the surface of the C / C composite material embedded with the SiC coating, and after brushing a layer of the slurry, drying is performed until the weight of the substrate with the slurry increases to 20% of the original weight of the substrate and drying and solidification are performed, to obtain a SiC-based coating preform; the SiC-based coating preform is carbonized at 900°C in an argon atmosphere for 2h, the carbonized SiC-based coating preform is embedded in silicon powder, and under vacuum, the temperature is raised to 1450°C at a rate of 3.5°C / min, and after holding for 2h, the temperature is lowered, to obtain a glassy carbon in-situ reaction SiC-based high-temperature coating.

[0040] Comparative Example 1 10g of phenolic resin is weighed into an alumina crucible, which is placed in a tubular heat treatment furnace, and under an argon protective atmosphere, heat treatment is performed at 900°C for 2h to obtain glassy carbon, which is ground into glassy carbon powder with a particle size of 5-30µm using a mortar; According to the mass percentage, 27% of the glassy carbon powder is mixed with 73% of the mixed ceramic powder, which is added to a 10wt% phenolic resin anhydrous ethanol solution, and after sufficient stirring for 5h under a magnetic stirrer, a mixed slurry is obtained; wherein the mixed ceramic powder includes SiC, HfB2 and MoSi2 powder, and the mass ratio is: SiC:HfB2:MoSi2=5:4:1; The mixed slurry is uniformly brushed on the surface of the C / C composite material embedded with the SiC coating, and after brushing a layer of the slurry, drying is performed until the weight of the substrate with the slurry increases to 20% of the original weight of the substrate and drying and solidification are performed, to obtain a SiC-based coating preform; the SiC-based coating preform is carbonized at 900°C in an argon atmosphere for 2h, the carbonized SiC-based coating preform is embedded in silicon powder, and under vacuum, the temperature is raised to 1450°C at a rate of 3.5°C / min, and after holding for 2h, the temperature is lowered, to obtain a glassy carbon in-situ reaction SiC-based high-temperature coating.

[0041] Comparative Example 2 The mixed ceramic powder is added to a 10wt% phenolic resin anhydrous ethanol solution, and after sufficient stirring for 5h under a magnetic stirrer, a mixed slurry is obtained; wherein the mixed ceramic powder includes SiC, HfB2 and MoSi2 powder, and the mass ratio is: SiC:HfB2:MoSi2=5:4:1; The mixed slurry is uniformly brushed on the surface of the C / C composite material embedded with the SiC coating, and after brushing a layer of the slurry, drying is performed until the weight of the substrate with the slurry increases to 20% of the original weight of the substrate and drying and solidification are performed, to obtain a SiC-based coating preform; the SiC-based coating preform is carbonized at 900°C in an argon atmosphere for 2h, the carbonized SiC-based coating preform is embedded in silicon powder, and under vacuum, the temperature is raised to 1450°C at a rate of 3.5°C / min, and after holding for 2h, the temperature is lowered, to obtain a glassy carbon in-situ reaction SiC-based high-temperature coating.

[0042] Comparative Example 3 The mixed ceramic powder was added to a phenolic resin anhydrous ethanol solution with a concentration of 16wt%, and after being stirred under a magnetic stirrer for 5h, a mixed slurry was obtained; wherein the mixed ceramic powder included SiC, HfB2 and MoSi2 powder, and the mass ratio was: SiC:HfB2:MoSi2=5:4:1; The mixed slurry was uniformly brushed on the surface of the C / C composite material embedded with the SiC coating, and after brushing a layer of slurry, drying was performed until the weight of the substrate with the slurry increased by 20% of the original weight of the substrate and drying and curing were performed, to obtain a SiC-based coating preform; the SiC-based coating preform was carbonized at 900℃ in an argon atmosphere for 2h, and the carbonized SiC-based coating preform was embedded in silicon powder and heated to 1450℃ at a rate of 3.5℃ / min under vacuum, and after holding for 2h, the temperature was lowered, to obtain a glassy carbon in-situ reaction SiC-based high-temperature coating.

[0043] To further illustrate the beneficial effects of the present application, the coatings prepared in Example 1 and Comparative Examples 1-3 were tested, and the test results are shown in Figures 4 to 7 The glassy carbon in-situ reaction SiC-based coating prepared in Example 1 had an average thickness of about 300µm, and compared with the XRD of the comparative example, the residual Si content was greatly reduced, and the carbon content was moderate. By precisely adjusting the carbon-silicon ratio, the residual silicon content of the coating was significantly reduced, and the performance was optimized. The high-temperature coating prepared in Comparative Example 1 had obvious cracks on the surface of the coating, and the average thickness of the coating was about 280µm. Compared with the XRD pattern of the coating prepared in Example 1, although the residual Si content was greatly reduced, the carbon content was significantly increased, and precise adjustment of the carbon-silicon ratio of the coating was not achieved. The coating prepared in Comparative Example 2 had a thickness of 335µm, and compared with the coating prepared in Example 1, the residual Si content was greatly increased, indicating that the introduction of glassy carbon would produce a large amount of free silicon during the silicon infiltration process, reducing the high-temperature stability of the coating. The coating prepared in Comparative Example 3 had obvious cracks on the surface, which indicated that excessive phenolic resin would produce thermal stress due to volume shrinkage during the carbonization process, leading to cracks in the coating, and oxygen entering the substrate from the cracks would greatly reduce the oxidation resistance and protection performance of the coating.

[0044] Example 2 10g of polyvinyl alcohol was weighed into an alumina crucible, which was placed in a tubular heat treatment furnace, and was heat-treated at 900℃ for 2h in an argon protective atmosphere to obtain glassy carbon. The glassy carbon was ground into a micron-sized glassy carbon powder with a particle size of 5-30µm using a mortar. Mix 18% glassy carbon powder with 82% mixed ceramic powder by mass percentage, add to a phenolic resin anhydrous ethanol solution with a concentration of 15wt%, and obtain a mixed slurry after fully stirring for 6h under a magnetic stirrer; wherein the mixed ceramic powder comprises SiC, HfB2 and HfC powders, and the mass ratio is: SiC:HfB2:HfC=5:3:2; Coat the mixed slurry uniformly on the surface of the C / C composite material embedded with the SiC coating, dry after coating a layer of slurry, until the weight of the substrate with the slurry increases to 15% of the original substrate weight and is dried and solidified, to obtain a SiC-based coating preform; carbonize the SiC-based coating preform in an argon atmosphere at 1000℃ for 2h, embed the carbonized SiC-based coating preform in silicon powder, and heat to 1400℃ at a rate of 4℃ / min under vacuum, keep the temperature for 2h, and then cool down, to obtain a glassy carbon in-situ reaction SiC-based high-temperature coating.

[0045] Example 3 Weigh 10g of polyvinyl alcohol into an alumina crucible, put it into a tubular heat treatment furnace, and heat at 800℃ for 4h in an argon protective atmosphere to obtain glassy carbon, which is ground into 5-30µm micron-sized glassy carbon powder using a mortar; Mix 15% glassy carbon powder with 85% mixed ceramic powder by mass percentage, add to a phenolic resin anhydrous ethanol solution with a concentration of 12wt%, and obtain a mixed slurry after fully stirring for 6h under a magnetic stirrer; wherein the mixed ceramic powder comprises SiC, ZrSi2 and TaSi2 powders, and the mass ratio is: SiC:ZrSi2:TaSi2=7:2:1; Coat the mixed slurry uniformly on the surface of the C / C composite material embedded with the SiC coating, dry after coating a layer of slurry, until the weight of the substrate with the slurry increases to 25% of the original substrate weight and is dried and solidified, to obtain a SiC-based coating preform; carbonize the SiC-based coating preform in an argon atmosphere at 1100℃ for 1h, embed the carbonized SiC-based coating preform in silicon powder, and heat to 1400℃ at a rate of 6℃ / min under vacuum, keep the temperature for 3h, and then cool down, to obtain a glassy carbon in-situ reaction SiC-based high-temperature coating.

[0046] Example 4 Weigh 10g of phenolic resin into an alumina crucible, put it into a tubular heat treatment furnace, and heat at 110℃ for 1h in an argon protective atmosphere to obtain glassy carbon, which is ground into 5-30µm micron-sized glassy carbon powder using a mortar; Mix 25% glassy carbon powder with 75% mixed ceramic powder by mass percentage, add to a 10wt% phenolic resin ethanol solution, and after stirring for 6h under a magnetic stirrer, a mixed slurry is obtained; wherein the mixed ceramic powder comprises SiC, MoSi2, ZrSi2 and TaSi2 powder, and the mass ratio is: SiC:MoSi2:ZrSi2:TaSi2=6:2:1:1; The mixed slurry is evenly brushed on the surface of the C / C composite material embedded with the SiC coating, and after brushing a layer of slurry, drying is performed until the weight of the substrate with the slurry increases to 20% of the original substrate weight and drying and curing are performed, to obtain a SiC-based coating preform; the SiC-based coating preform is carbonized at 1000℃ in an argon atmosphere for 3h, and the carbonized SiC-based coating preform is embedded in silicon powder and heated to 1450℃ at a rate of 10℃ / min under vacuum, and after holding for 1h, cooling is performed, to obtain a glassy carbon in-situ reaction SiC-based high-temperature coating.

[0047] The application provides a glassy carbon in-situ reaction SiC-based coating prepared by the above-mentioned preparation method of a glassy carbon in-situ reaction SiC-based coating, which generates SiC by in-situ reaction of glassy carbon as a supplementary carbon source and free silicon, and the SiC has excellent high-temperature stability and oxidation resistance, and can effectively prevent oxygen from further penetrating into the C / C composite material, so that the glassy carbon in-situ reaction SiC-based coating has better high-temperature oxidation resistance, thereby having a longer service life. At the same time, the in-situ generated SiC is closely combined with the surrounding material, can fill the pores and defects in the coating, makes the coating structure more dense, and further improves the performance of the coating, so that the coating reaches the best balance in hardness, wear resistance, oxidation resistance and the like.

[0048] The above-mentioned glassy carbon in-situ reaction SiC-based coating or the above-mentioned preparation method of a glassy carbon in-situ reaction SiC-based coating is applied to the preparation of a C / C composite material component or an aerospace device. Since the coating has more excellent high-temperature oxidation resistance, the prepared C / C composite material component or aerospace device can work stably under extremely high-temperature conditions, the coating can effectively prevent oxygen from contacting the C / C composite material, reduce oxidation damage, reduce the mass loss and performance attenuation of the material due to oxidation, and thereby significantly prolong the service life of the C / C composite material component and the aerospace device.

[0049] In summary, the application provides a glassy carbon in-situ reaction SiC-based coating, a preparation method and applications. By preparing glassy carbon powder, and making it react with residual silicon in the subsequent silicon infiltration process to generate SiC, the content of free silicon in the coating is significantly reduced, the high-temperature stability of the coating is improved, and the density of the glassy carbon in-situ reaction SiC-based coating is improved. The preparation method has significant advantages in improving material performance, optimizing coating composition and preparation process, controlling cost, improving reaction activity, and the diversity of ceramic powder selection, and provides a reliable solution for the industrial application of high-performance silicon infiltration coating.

[0050] The above merely describes the preferred embodiments of the application and is not intended to limit the technical solutions of the application in any way. Those skilled in the art should understand that, without departing from the spirit and principle of the application, the technical solutions can be modified and replaced in several simple ways, and these modifications and replacements also belong to the protection scope covered by the claims.

Claims

1. A method for preparing a glassy carbon in-situ reaction SiC-based coating, characterized in that: include: Preparation of glassy carbon powder using carbon-containing precursors; A mixed slurry is prepared using glassy carbon powder and mixed ceramic powder; the mixed ceramic powder is a mixed ceramic powder containing SiC powder; preparing a SiC-based coating preform using the mixed slurry; The SiC-based coating preform is subjected to carbonization treatment and siliconization treatment in sequence to obtain the SiC-based coating.

2. The method for preparing a glassy carbon in-situ reaction SiC-based coating according to claim 1, characterized in that: The carbon-containing precursor is phenolic resin or polyvinyl alcohol.

3. The method for preparing a glassy carbon in-situ reaction SiC-based coating according to claim 1, wherein: The method for preparing glassy carbon powder using a carbon-containing precursor is as follows: The carbon-containing precursor is pyrolyzed at 800°C to 1100°C to convert it into glassy carbon; The glassy carbon is processed into micron-sized powder with a particle size of 5 to 30 μm to obtain glassy carbon powder.

4. The method for preparing a glassy carbon in-situ reaction SiC-based coating according to claim 1, characterized in that: The ceramic powder further comprises one or more of HfB2, HfC, MoSi2, ZrSi2 and TaSi2.

5. The method for preparing a glassy carbon in-situ reaction SiC-based coating according to claim 1, characterized in that: The method for preparing a mixed slurry using glassy carbon powder and ceramic powder is as follows: By mass percentage, 15% to 25% of glassy carbon powder and 75% to 85% of ceramic powder are mixed and dispersed in an anhydrous ethanol solution containing phenolic resin to obtain a mixed slurry; wherein the concentration of the phenolic resin in the anhydrous ethanol solution containing phenolic resin is 10wt% to 15wt%.

6. The method for preparing a glassy carbon in-situ reaction SiC-based coating according to claim 5, characterized in that: The mass ratio of SiC powder to other ceramic powders in the mixed ceramic powder is (50-70):(30-50).

7. The method for preparing a glassy carbon in-situ reaction SiC-based coating according to claim 1, characterized in that: The carbonization treatment is carried out under an argon atmosphere at a temperature of 800° C. to 1100° C.

8. The method for preparing a glassy carbon in-situ reaction SiC-based coating according to claim 1, characterized in that: The method of the siliconizing treatment is: The carbonized SiC-based coating preform is buried in silicon powder, heated to 1400°C to 1450°C at a rate of 3.5°C / min to 10°C / min under vacuum conditions, and kept warm for 1 to 3 hours to complete the siliconization treatment.

9. A glassy carbon in-situ reaction SiC-based coating, characterized in that: The SiC-based coating is prepared using the method for preparing the glassy carbon in-situ reaction SiC-based coating according to any one of claims 1 to 8.

10. Use of the glassy carbon in-situ reaction SiC-based coating according to claim 9 or the method for preparing the glassy carbon in-situ reaction SiC-based coating according to any one of 1 to 8 in the preparation of C / C composite materials or aerospace devices.

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