High-temperature-resistant high-toughness Cf / Si3N4 ceramic-based composite material and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant and high-toughness Cf / Si3N4 ceramic-based composite material and a preparation method thereof. The high-temperature-resistant and high-toughness Cf / Si3N4 ceramic-based composite material is prepared from the following raw materials in percentage by mass: 48.0 to 52.0 weight percent of PAN (Polyacrylonitrile) high-strength carbon fiber, 19.0 to 23.0 weight percent of silicon nitride particles, 14.0 to 22.0 weight percent of adhesive, 3.0 to 5.0 weight percent of nano SiO2 sol, 0.5 to 1.0 weight percent of high-purity graphite powder, 3.0 to 5.0 weight percent of dispersing aid and 2.5 to 5.0 weight percent of functional additive. The PAN high-strength carbon fiber and the silicon nitride particles are used as main body base materials, and the thermal stability, the obdurability and the like of the Cf / Si3N4 ceramic-based composite material are improved by optimizing the formula design and the preparation process, so that the quality and the performance of the Cf / Si3N4 ceramic-based composite material are remarkably improved, and the service life of the Cf / Si3N4 ceramic-based composite material is prolonged. And the requirements of a new generation of aviation high dynamic heat-carrying protection parts on materials can be well met.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber composite materials technology, and more specifically to a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material and its preparation method. Background Technology

[0002] With the rapid development of aerospace technologies such as hypersonic vehicles, reusable launch vehicles, and deep space probes, the performance requirements of structural components under extreme high-temperature conditions are continuously increasing. Especially in scenarios such as aerospace high-dynamic-load thermal protection components and hypersonic vehicle thermal protection systems, materials must simultaneously meet stringent requirements for ultra-high-temperature stability, thermal shock resistance, and toughness. Silicon nitride, due to its significantly superior high-temperature resistance and excellent thermal shock resistance compared to metals, has become a highly promising matrix material for aerospace thermal structures. Carbon fiber reinforcement, with its high strength and efficient toughening mechanism, can significantly improve the fracture toughness of composite materials. However, traditional carbon fiber composites still suffer from many problems, such as interfacial debonding under thermal cycling and severe fiber breakage. These defects make it difficult to meet the requirements of material lifespan and reliability for next-generation aerospace high-dynamic-load thermal protection components. Furthermore, traditional manufacturing processes, due to high-pressure injection impact, result in numerous air bubbles and significant fiber damage, leading to a decline in the quality of carbon fiber composites.

[0003] Therefore, to solve the aforementioned technical challenges, the injection method was modified. This invention provides a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material and its preparation method. The aim is to optimize the formulation design and preparation method, utilizing liquid molding technology and a low-pressure wetting strategy for slow penetration to prevent fiber erosion and displacement. During the impregnation process, this invention employs VARI injection and hot isostatic pressing technology to reduce porosity, thereby effectively minimizing fiber damage and improving the high-temperature resistance and toughness of the carbon fiber composite material. Summary of the Invention

[0004] This invention provides a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material and its preparation method. Using high-strength PAN carbon fiber and silicon nitride particles as the main matrix materials, and through optimized formulation design, the high-temperature resistance and toughness of the carbon fiber composite material are improved, thereby significantly enhancing the quality and performance of the carbon fiber ceramic matrix composite material to meet the requirements of aerospace high-dynamic heat-carrying protective components. Another objective of this invention is to provide a method for preparing the aforementioned high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material, with the following raw material composition by mass ratio: 48.0~52.0wt% PAN high-strength carbon fiber, 19.0~23.0wt% silicon nitride particles, 14.0~22.0wt% adhesive, 3.0~5.0wt% nano-SiO2 sol, 0.5~1.0wt% high-purity graphite powder, 3.0~5.0wt% dispersant, and 2.5~5.0wt% functional additives.

[0006] Preferably, the adhesive is prepared by mixing 7-10 wt% polyimide resin, 5-8 wt% phenolic modified epoxy resin, and 2-4 wt% cyanate ester resin, based on the percentage of the adhesive in the total mass of the composite material.

[0007] Preferably, the dispersing agent is obtained by mixing 2-3 wt% hyperbranched polysiloxane and 1-2 wt% organotitanate coupling agent, calculated as a percentage of the total mass of the composite material.

[0008] Preferably, the functional additive is obtained by mixing 1-2 wt% epoxy POSS, 0.5-1.0 wt% rare earth cerium complex, and 1-2 wt% vacuolated imidazole microcapsules, based on the percentage of the functional additive in the total mass of the composite material.

[0009] Preferably, the particle size of the PAN high-strength carbon fiber is 5~8μm; The silicon nitride particles have a particle size of 0.2~1.0 μm; The particle size of nano-SiO2 is 5~50nm in sol; The particle size of high-purity graphite powder is 1~5μm; The particle size of epoxy-based POSS is 1~3nm; The particle size of the latent imidazole microcapsules is 5~20μm.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material, comprising the following steps: (1) Raw material pretreatment According to the raw material composition, PAN carbon fibers are subjected to electrochemical oxidation treatment for 15-20 minutes to improve their surface properties and enhance their bonding ability with other components. Then, in a specific stage before subsequent composite treatment with silicon nitride particles, an organotitanate coupling agent (which is a component of the dispersing agent) accounting for 1-2 wt% of the total mass of the composite material is added. This is followed by drying to remove moisture and other impurities, ensuring the material's performance. Simultaneously, the silicon nitride particles are calcined to remove surface impurities and improve the particle surface condition. Then, the calcined silicon nitride particles are added to an aqueous solution of 3-aminopropyltriethoxysilane with a mass fraction of 1-3 wt% (the amount of 3-aminopropyltriethoxysilane added should be sufficient to fully submerge the silicon nitride particles to ensure that a uniform chemical bonding layer can be formed on the surface of the silicon nitride particles). The solution is refluxed at 75-85℃ for 1.5-2.5 hours to form a specific chemical bonding layer on the surface of the silicon nitride particles. Finally, the solution is vacuum dried at 110-130℃ to further remove moisture and other impurities.

[0011] Next, the pretreated PAN high-strength carbon fiber and surface-modified silicon nitride particles are wet-mixed to form a uniform suspension. Then, a three-dimensional four-way weaving technology is used to create a 1×1×1 structure with a fiber tension of 6N / bundle, so that the silicon nitride particles are embedded in the gaps between the carbon fiber bundles to form a carbon fiber-silicon nitride composite reinforcement.

[0012] (2) Slurry preparation After mixing and grinding nano-SiO2 sol and high-purity graphite powder multiple times, adhesives, dispersants and some functional additives are added, and vacuum degassing is carried out for 1-2 hours until the viscosity is 600-800 mPa·s to obtain a slurry. (3) Liquid molding After preheating the prepared mold to 75-85℃, maintain it in a vacuum environment (pressure -0.095MPa) for 10-20 minutes. At the same time, stir the carbon fiber-silicon nitride composite reinforcement and the slurry at 75-85℃ to ensure that the carbon fiber-silicon nitride composite reinforcement is uniformly dispersed in the slurry.

[0013] Subsequently, using RTM technology, the uniformly mixed slurry was injected into the mold at a pressure of 0.8-1.0 MPa for 8-10 minutes. After filling, the injection port was closed. Next, VARI (vacuum-assisted resin injection) was performed to further fill the tiny voids in the mold with the slurry, maintaining this pressure at -0.09 MPa at the edge for 15-20 minutes. Finally, a positive pressure of 0.2 MPa and a negative pressure of -0.09 MPa were applied simultaneously and held for 30 minutes to ensure the slurry fully filled the mold and created a dense internal structure, thus obtaining the blank. (4) In-mold curing and high-pressure carbonization The blank is subjected to a stepped heating technique, maintaining a pressure of 0.5 MPa throughout the process, heating at 5°C / min to 75-80°C and holding for 0.5-1 h, then heating at 6°C / min to 110-120°C and holding for 1.5-2 h, and finally heating at 5°C / min to 180°C and holding for 3 h, and then cooling at 4°C / min to 50-60°C for demolding. The blank is then placed in a hot isostatic pressing furnace under a pressure of 5 MPa in a N2 atmosphere and heated at 5°C / min to 600°C and held for 2-3 h to obtain a green blank. (5) Final billet forming and finishing For the aforementioned green body, functional additives are added in a specific ratio. After mixing the functional additives with the green body, the mixture is placed in a vacuum impregnation tank and vacuumed to -0.095 MPa at 145-155℃ for 2 hours to allow the additives to fully penetrate into the material pores. It is then transferred to a high-temperature pyrolysis furnace and cyclically treated at 900℃ five times (holding for 1 hour each time) to promote chemical bonding between the additives and the matrix. After pyrolysis, the surface is finished with a diamond grinding wheel (first rough grinding to Ra≤1.6μm, then fine grinding to Ra≤0.8μm). Finally, an 80-120μm thick alumina-yttrium oxide stabilized zirconia (YSZ) composite coating is sprayed to obtain a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material.

[0014] Preferably, the drying in step (1) is performed at a temperature of 100-110°C for 25-30 minutes; The calcination is performed by air calcination at 750-800℃ for 1-2 hours; The hot pressing is performed at 20°C and a pressure of 0.3 MPa for 5 minutes.

[0015] Preferably, the amount of functional additives used in step (2) is 1.0 to 3.0 wt% of the total amount of composite material.

[0016] Preferably, in step (5), the functional additives account for 1.5 to 2.0 wt% of the total amount of the composite material, of which 0.8 to 1.2 wt% of epoxy POSS is added to enhance heat resistance and interfacial bonding, 0.4 to 0.6 wt% of rare earth cerium complex is added to catalyze the cracking reaction and reduce the curing temperature, and 0.3 to 0.7 wt% of latent imidazole microcapsules are added to delay the curing rate and reduce internal stress.

[0017] Preferably, the diamond grinding wheel is finished by first rough grinding the surface to Ra≤1.6μm, and then fine grinding to Ra≤0.8μm.

[0018] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: (1) PAN high-strength carbon fiber and silicon nitride materials have excellent properties such as high melting point and high toughness. Compared with traditional carbon fiber composite materials, PAN high-strength carbon fiber and silicon nitride materials perform better under harsh conditions such as high temperature, high pressure and high load. This invention improves hardness and creep resistance by optimizing the formula design, that is, using PAN high-strength carbon fiber as the matrix phase, silicon nitride, nano-SiO2 sol and high-purity graphite powder as the reinforcing phase, while improving the resin matrix. Polyimide resin, phenolic modified epoxy and cyanate ester resin are used as the binder phase, which further improves the density of carbon fiber. The resulting Cf / Si3N4 ceramic matrix composite material has significantly improved quality and performance.

[0019] (2) This invention uses PAN high-strength carbon fiber as the main matrix material, which can increase load-bearing capacity and improve toughness, making the material more resilient. Furthermore, the purity of the material phase is improved through stepped heating and high-pressure carbonization, making the material more resistant to high temperatures. The resulting Cf / Si3N4 ceramic matrix composite material has the characteristics of high temperature resistance and high toughness, which not only improves the service life of carbon fiber materials, but also well meets the requirements of the new generation of high dynamic heat protection components for aerospace for material life and reliability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating the preparation process of the high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to an embodiment of the present invention.

[0022] Figure 2 The accompanying drawings are related to the testing of the product of this invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention relates to a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material, the raw materials of which are matrix material, adhesive, functional filler, dispersant and functional additive.

[0025] The matrix material contains PAN high-strength carbon fiber and silicon nitride particles; the adhesive contains polyimide resin, phenolic modified epoxy, and cyanate ester resin; the functional filler contains nano-SiO2 sol and high-purity graphite powder; the dispersing agent contains hyperbranched polysiloxane and organotitanium ester coupling agent; and the functional additives contain epoxy group POSS, rare earth cerium complex, and latent imidazole microcapsules.

[0026] The raw materials and their amounts used in the embodiments of the present invention are shown in Table 1, and the raw material composition ratios of each embodiment are shown in Table 2.

[0027] Table 1

[0028] Table 2

[0029] The preparation method of the high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material in the embodiments of the present invention is as follows: Figure 1 As shown, the steps are as follows: (1) Raw material pretreatment According to the raw material composition, PAN carbon fiber is electrochemically oxidized for 15-20 min, then an organic titanate coupling agent is added and dried at 100-110℃ for 25-30 min; at the same time, silicon nitride particles are calcined in air at 750-800℃ for 1-2 h, then an aqueous solution of 3-aminopropyltriethoxysilane is added and refluxed at 80℃ for 2 h, and finally vacuum dried at 120℃; then a 1×1×1 structure is obtained by using three-dimensional four-way weaving technology with a fiber tension of 6 N / bundle, and hot-pressed at 0.3 MPa for 5 min at 20℃ to obtain fiber bundles.

[0030] (2) Preparation of adhesive slurry After mixing and grinding the above-mentioned raw materials, nano-SiO2 sol and high-purity graphite powder multiple times, adhesive, dispersant and functional additives (total amount range set to 1.0~3.0wt%) are added, and vacuum degassing is carried out for 1-2 hours until the viscosity is 600-800mPa·s to obtain slurry.

[0031] (3) Liquid molding After preheating the prepared mold to 80°C, it is kept under vacuum (-0.095MPa) for 15 minutes to remove moisture. The slurry is also kept at 80°C. Using RTM technology, injection is started at a pressure of 0.8-1.0MPa. After filling the mold for 8-10 minutes, the injection port is closed. Then, VARI injection is performed, and the edge pressure (-0.09MPa) is maintained for 15-20 minutes. Finally, the blank is obtained after holding the pressure at 0.2MPa positive pressure and -0.09MPa negative pressure for 30 minutes.

[0032] (4) In-mold curing and high-pressure carbonization The molded body is subjected to a stepped heating technique. The pressure is maintained at 0.5 MPa throughout the process. The temperature is increased to 75-80°C at a rate of 5°C / min and held for 0.5-1 h. Then, the temperature is increased to 110-120°C at a rate of 6°C / min and held for 1.5-2 h. Finally, the temperature is increased to 180°C at a rate of 5°C / min and held for 3 h. Then, the temperature is decreased to 50-60°C at a rate of 4°C / min for demolding. The blank is then wrapped with graphite paper and placed in a hot isostatic pressing furnace under a pressure of 5 MPa in a N2 atmosphere. The temperature is increased to 600°C at a rate of 5°C / min and held for 2-3 h to ensure complete carbonization of the resin.

[0033] (5) Final billet forming and finishing For the aforementioned green body, functional additives are added in a specific ratio (functional additives account for 1.5~2.0 wt% of the total composite material, of which epoxy POSS is added at 0.8~1.2 wt%, rare earth cerium complex at 0.4~0.6 wt%, and latent imidazole microcapsules at 0.3~0.7 wt%). After the functional additives are mixed with the green body, the mixture is placed in a vacuum impregnation tank and vacuumed to -0.095 MPa at 150°C for 2 hours to allow the additives to fully penetrate into the material pores. Then, it is transferred to a high-temperature pyrolysis furnace and cyclically treated at 900°C 5 times, with each treatment lasting 1 hour. After pyrolysis, it is precision machined with a diamond grinding wheel and finally sprayed with a 100 μm thick alumina-yttrium oxide stabilized zirconia (YSZ) composite coating to obtain a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material.

[0034] The preparation process parameters for each embodiment are shown in Table 3.

[0035] Table 3

[0036] Performance testing: The fracture toughness of the Cf / Si3N4 ceramic matrix composite material was tested using a single-sided pre-cracked beam test; thermal stability was analyzed using thermogravimetric analysis; and flexural strength was calculated using a three-point bending test. The performance indicators of the Cf / Si3N4 ceramic matrix composite material in this embodiment are shown in Table 4.

[0037] Table 4

[0038] Comparative experiments have demonstrated that the raw material ratio and process design of this invention can significantly improve the high temperature resistance (by 12-18%), fracture toughness (by 20-58%), and flexural strength (by 19-35%) of the composite material, meeting the stringent requirements of aerospace thermal protection components.

[0039] The various embodiments and comparative examples in this specification are described in a progressive manner. Each embodiment and comparative example focuses on the differences from the others. The same or similar parts between the various embodiments and comparative examples can be referred to each other.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material, characterized in that, The raw material composition by mass ratio is as follows: 48.0~52.0 wt% PAN high-strength carbon fiber, 19.0~23.0 wt% silicon nitride particles, 14.0~22.0 wt% adhesive, 3.0~5.0 wt% nano-SiO2 sol, 0.5~1.0 wt% high-purity graphite powder, 3.0~5.0 wt% dispersant, and 2.5~5.0 wt% functional additives.

2. The high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 1, characterized in that, The adhesive is obtained by mixing 7-10 wt% polyimide resin, 5-8 wt% phenolic modified epoxy resin, and 2-4 wt% cyanate ester resin, based on the percentage of the total mass of the composite material.

3. The high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 1, characterized in that, The dispersing agent is calculated as a percentage of the total mass of the composite material. It is obtained by mixing 2-3 wt% hyperbranched polysiloxane and 1-2 wt% organotitanate coupling agent.

4. The high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 1, characterized in that, The functional additive is calculated as a percentage of the total mass of the composite material. The functional additive is obtained by mixing 1-2 wt% epoxy POSS, 0.5-1.0 wt% rare earth cerium complex, and 1-2 wt% vacuolated imidazole microcapsules.

5. The high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 1, characterized in that, The particle size of the PAN high-strength carbon fiber is 5~8μm; The silicon nitride particles have a particle size of 0.2~1.0 μm; The particle size of nano-SiO2 is 5~50nm in sol; The particle size of high-purity graphite powder is 1~5μm; The particle size of epoxy-based POSS is 1~3nm; The particle size of the latent imidazole microcapsules is 5~20μm.

6. A method for preparing a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Raw material pretreatment According to the raw material composition, PAN carbon fiber is subjected to electrochemical oxidation treatment for 15-20 minutes. Then, before the subsequent composite treatment with silicon nitride particles, an organic titanate coupling agent accounting for 1-2 wt% of the total mass of the composite material is added, followed by drying. Meanwhile, the silicon nitride particles are calcined, and then the calcined silicon nitride particles are added to an aqueous solution of 3-aminopropyltriethoxysilane with a mass fraction of 1-3 wt%, refluxed at 75-85℃ for 1.5-2.5 h, and finally vacuum dried at 110-130℃. Next, the pretreated PAN high-strength carbon fiber and surface-modified silicon nitride particles are wet-mixed to form a uniform suspension. A 1×1×1 structure is formed using three-dimensional four-way weaving technology with a fiber tension of 6N / bundle. Then, hot pressing is performed to embed the silicon nitride particles into the gaps between the carbon fiber bundles, forming a carbon fiber-silicon nitride composite reinforcement. (2) Slurry preparation Nano-SiO2 sol and high-purity graphite powder are mixed and ground multiple times to ensure uniform dispersion. Then, adhesives, dispersants, and some functional additives are added, and vacuum degassing is carried out for 1-2 hours until the viscosity reaches 600-800 mPa·s to obtain the slurry; (3) Liquid molding After preheating the prepared mold to 75-85℃, keep it in a vacuum environment for 10-20 minutes. At the same time, stir the carbon fiber-silicon nitride composite reinforcement and the slurry evenly at 75-85℃ to ensure that the carbon fiber-silicon nitride composite reinforcement is evenly dispersed in the slurry. Then, using RTM technology, the uniformly mixed slurry is injected into the mold under a pressure of 0.8-1.0 MPa. The filling time is 8-10 minutes. After the mold is filled, the injection port is closed, and VARI injection is performed to further fill the tiny gaps in the mold with slurry. The pressure is maintained at -0.09 MPa at the edge for 15-20 minutes. Finally, a positive pressure of 0.2 MPa and a negative pressure of -0.09 MPa are applied simultaneously and the pressure is maintained for 30 minutes to obtain the blank. (4) In-mold curing and high-pressure carbonization The blank is subjected to a stepped heating technique, maintaining a pressure of 0.5 MPa throughout the process, heating at 5°C / min to 75-80°C and holding for 0.5-1 h, then heating at 6°C / min to 110-120°C and holding for 1.5-2 h, and finally heating at 5°C / min to 180°C and holding for 3 h, and then cooling at 4°C / min to 50-60°C for demolding. The blank is then placed in a hot isostatic pressing furnace under a pressure of 5 MPa in a N2 atmosphere and heated at 5°C / min to 600°C and held for 2-3 h to obtain a green blank. (5) Final billet forming and finishing For the aforementioned green body, functional additives are added in a specific ratio. After mixing the functional additives with the green body, the mixture is placed in a vacuum impregnation tank and vacuumed to -0.095MPa at 145-155℃ and maintained for 2 hours to allow the additives to fully penetrate into the material pores. Then, it is transferred to a high-temperature pyrolysis furnace and cyclically treated at 900℃ 5 times, with each treatment lasting 1 hour. After pyrolysis, it is precision machined with a diamond grinding wheel and finally sprayed with an alumina-yttrium oxide stabilized zirconia composite coating with a thickness of 80~120μm to obtain a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material.

7. The method for preparing a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 6, characterized in that, The drying process described in step (1) involves drying at 100-110℃ for 25-30 minutes. The calcination is performed by air calcination at 750-800℃ for 1-2 hours; The hot pressing is performed at 20°C and a pressure of 0.3 MPa for 5 minutes.

8. The method for preparing a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 6, characterized in that, In step (2), the amount of functional additives used is 1.0 to 3.0 wt% of the total amount of composite material.

9. The method for preparing a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 8, characterized in that, In step (5), the functional additives account for 1.5 to 2.0 wt% of the total amount of the composite material, of which 0.8 to 1.2 wt% of epoxy POSS, 0.4 to 0.6 wt% of rare earth cerium complex, and 0.3 to 0.7 wt% of latent imidazole microcapsules are added.

10. The method for preparing a high-temperature resistant and tough Cf / Si3N4 ceramic matrix composite material according to claim 6, characterized in that, The diamond grinding wheel finishing process involves first rough grinding the surface to Ra≤1.6μm, and then fine grinding to Ra≤0.8μm.

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