SiC@BN core-shell nanowire periodic array reinforced Si3N4 high-temperature wave-absorbing ceramic coating and preparation method thereof

Abstract

The application discloses a SiC@BN core-shell nanowire periodic array reinforced Si3N4 high-temperature wave-absorbing ceramic coating, which is composed of SiC nanowires, a BN shell layer and a Si3N4 ceramic matrix. The SiC nanowires and the BN shell layer are obtained through a chemical vapor infiltration process, and form a core-shell structure to obtain SiC@BN core-shell nanowires, which can avoid oxidation of the SiC nanowires and improve the dielectric constant of the SiC nanowires. The SiC@BN core-shell nanowires are arranged in a three-dimensional periodic array. The Si3N4 ceramic matrix is prepared through the chemical vapor infiltration process, and the Si3N4 ceramic matrix is uniformly filled in the pores between the SiC@BN core-shell nanowires. Through macro-micro multi-scale structure design, lattice distortion, stacking faults and interface defects are introduced in the micro scale to promote the absorption and attenuation loss of the incident electromagnetic wave, and the surface electric field coupling effect and multiple scattering loss mechanism are introduced in the macro scale to realize the widening of the effective absorption band and the synergistic improvement of the electromagnetic wave absorption characteristics.

Description

Technical Field

[0001] This invention patent relates to a high-temperature absorbing coating, and more particularly to a SiC@BN core-shell nanowire periodic array-enhanced Si3N4 high-temperature absorbing ceramic coating, which can be used for long-term service in high-temperature and complex environments. Technical Background

[0002] With the rapid development of avionics technology, "detection equals destruction" has become the main theme of modern warfare. To improve the battlefield penetration and survivability of future stealth fighters, reducing the target's radiation or scattering characteristics is of significant military importance and a crucial research direction for military technology in various countries. Among existing detection technologies, radar is the most effective and reliable target detection method and remains the primary threat to fighter jets. However, engine exhaust nozzles generate strong cavity scattering of radar waves, making them the most significant source of radar exposure and the most critical weakness limiting the all-aspect stealth capabilities of fighter jets. Without altering the exhaust nozzle's shape and aerodynamic characteristics, using high-temperature absorbing materials can significantly reduce the radar cross-section, representing a crucial technical approach to achieving radar stealth for fighter jets.

[0003] Continuous silicon carbide fiber-reinforced silicon carbide (SiC / SiC) ceramic matrix composites are highly promising high-temperature structural microwave absorbing materials, and have been successfully tested on the exhaust nozzles of various military and civilian aircraft engines, including the F136. However, their high dielectric constant and low loss characteristics result in insufficient absorption capacity for electromagnetic waves and a narrow effective absorption bandwidth, which greatly limits the stealth application of SiC / SiC composites in high-temperature fields. Applying a microwave absorbing coating to the surface of SiC / SiC composites can effectively reduce the radar cross-section of targets; however, during flight, the exhaust nozzle temperature of fighter jets can reach 1000℃. Currently available room-temperature microwave absorbing materials are insufficient to meet the requirements of high-temperature stealth, and cannot guarantee the battlefield survivability of stealth fighters. Furthermore, relying solely on the electromagnetic parameter control of the material itself is insufficient to achieve broadband microwave absorption. Combining periodic structures with microstructure design in high-temperature microwave absorbing coatings is an effective way to improve the stealth performance of fighter jets; however, the macro-micro synergistic mechanism of this effect on microwave absorption performance remains unclear and requires further research.

[0004] Chinese invention patent application number 201410753360.9 discloses a method for preparing a high-temperature resistant nano-absorbing agent and a microwave absorbing coating. The main preparation process is as follows: 1. Preparation of the absorbing agent: First, weigh tin tetrachloride, deionized water, ethanol, and acetylacetone. After preparing the above raw materials into a solution, add inorganic salts such as NaCl. After fully dissolving, evaporate a certain amount of the solution and heat the solution in a microwave to obtain a loose powder. Add template materials such as NP-10 to the powder, stir evenly, and then heat-treat in a muffle furnace to obtain the final powder. 2. Preparation of the coating: Spray a transition layer containing NiAl with a thickness of 0.05-0.2 mm onto a sandblasted alloy plate as the substrate; spray the microwave absorbing agent onto the transition layer with a thickness controlled at 0.5-2 mm. The resulting coating needs to be heat-treated at 400-900℃ for 1-10 hours to obtain a high-temperature resistant absorbing coating. The absorbing frequency band of the final coating is mainly between 8-18 GHz, and the absorption performance decreases by less than 20% at 1000℃. The main characteristics of this coating are that it can produce a significant absorbing effect with a relatively thin coating thickness, and it has good high-temperature resistance, maintaining a certain absorbing performance even at high temperatures; the coating has good adhesion to the substrate and a certain degree of thermal shock resistance.

[0005] Chinese invention patent application number 201410366766.1 discloses a high-bonding-strength, high-temperature resistant microwave-absorbing coating slurry and its preparation method. The slurry is characterized by the following raw material components and their mass percentages: 34-62% absorbent, 3-6% sintering aid, and 35-60% organic solvent. The slurry is prepared by placing the weighed organic solvent, absorbent, and sintering aid into a container and mixing them in a mixer. The slurry prepared by this invention can be coated onto the surface of metal materials such as Fe, Al, and Cu. After sintering in a reducing atmosphere, a high-bonding-strength, high-temperature resistant microwave-absorbing coating is obtained. This invention allows for adjusting the slurry viscosity by modifying the raw material ratio, making it suitable for different application processes such as brushing, screen printing, and spraying. The preparation process is simple, low-cost, and exhibits excellent performance.

[0006] Chinese invention patent application number 201210555252.1 discloses a broadband silicon carbide high-temperature absorbing coating and its preparation method, mainly addressing the problems of poor high-temperature resistance and complex processes in existing absorbing coatings. The above-mentioned absorbing coating uses silicon carbide micropowder as the main absorbing agent, and the absorption frequency band of the coating is adjusted by controlling the proportion of silicon carbide micropowder with different morphologies. Preparation method: 1. Coating preparation: Weigh the silicon carbide micropowder, oxide, silicate binder, surfactant, and deionized water according to the specified amounts. Mix the above raw materials and ball-mill for 4 hours to obtain the absorbing coating. 2. Coating preparation: Sandblast the alloy as the substrate, and then spray a NiCrAlY transition layer onto the substrate using a thermal spraying method. Spray the prepared absorbing coating onto the transition layer, air-dry the coating at room temperature, and after the coating reaches surface dryness, place it in an oven to dry at a temperature between 50-180℃. After drying, the coating is heat-treated at 600℃-1200℃ for 1-12 hours. After the coating is cooled in the furnace, a high-temperature absorbing coating is obtained. The absorption frequency band of the obtained coating is mainly between 2-20 GHz. It has good high-temperature resistance, wide absorption frequency band, good thermal shock resistance, good coating adhesion, and the ability to withstand high-temperature airflow erosion. It can meet the requirements of aero-engine operating conditions for absorption performance.

[0007] Chinese invention patent application number 202211386956.0 discloses a method for preparing a high-temperature resistant microwave absorbing coating, belonging to the field of microwave absorbing material technology. The preparation method includes the following steps: S1. Thoroughly mixing iron-cobalt alloy powder, phenolic resin adhesive, organic solvent, and silane coupling agent to obtain a mixed slurry; S2. Under grinding conditions, adding organic solvent to the mixed slurry to adjust the viscosity of the mixed slurry, obtaining a microwave absorbing coating; S3. Spraying the microwave absorbing coating onto the surface of a substrate to obtain a high-temperature resistant microwave absorbing coating. The preparation method of this invention is simple and controllable, and the obtained microwave absorbing coating has excellent high-temperature resistance, microwave absorption performance, and mechanical properties, meeting high-temperature requirements.

[0008] Chinese invention patent application number 201610398367.2 discloses a high-temperature resistant microwave absorbing coating, its preparation method, and its application. The high-temperature resistant microwave absorbing coating comprises a coating structure mainly formed by the aggregation of numerous small-sized flat particles. The coating structure also contains numerous vertical cracks extending along the thickness direction of the coating. The small-sized flat particles include Ti3AlC2 small-sized flat particles and Al2O3 small-sized flat particles. The preparation method includes: providing a suspension containing uniformly dispersed Ti3AlC2 particles and Al2O3 particles; and applying the suspension to the surface of a substrate using a plasma spraying process to form the high-temperature resistant microwave absorbing coating. Based on the excellent high-temperature stability and high-temperature oxidation resistance of Ti3AlC2, this invention prepares a Ti3AlC2 / Al2O3 high-temperature absorbing coating. At the same time, by introducing vertical cracks inside the coating and using suspension plasma spraying technology, a absorbing coating with both "small-sized flat particles" and vertical cracks is obtained. This gives it excellent absorbing performance, high-temperature oxidation resistance and thermal shock resistance, which can be applied in the field of absorbing materials in various aerospace vehicles.

[0009] As shown in the above patents, a high-temperature absorbing ceramic coating material is disclosed. However, there is little research on the effective absorption frequency band of the absorbing ceramic coating, making it difficult to achieve effective absorption in a specific waveband, which limits the further application of high-temperature absorbing ceramics. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a SiC@BN core-shell nanowire periodic array-enhanced Si3N4 high-temperature absorbing ceramic coating that integrates wide bandwidth, strong absorption, high temperature resistance, and oxidation resistance.

[0011] The technical solution adopted to achieve the purpose of this invention patent is: a SiC@BN core-shell nanowire periodic array enhanced Si3N4 high-temperature microwave absorbing ceramic coating, composed of SiC nanowires, a BN shell, and a Si3N4 ceramic substrate. The SiC nanowires and BN shell are obtained through a chemical vapor infiltration process, forming a core-shell structure to obtain SiC@BN core-shell nanowires. The diameter of the SiC nanowires is 1-2 μm, and the thickness of the BN shell is 300-400 nm. The BN shell is uniformly distributed on the surface of the SiC nanowires, preventing oxidation of the SiC nanowires while improving the dielectric constant of the SiC nanowires, thereby increasing the electromagnetic wave transmittance by 50-70%. The SiC@BN core-shell nanowires are arranged in a three-dimensional periodic array. The periodic units of the three-dimensional periodic array are circular, square, or triangular, with a unit size of 6-10 mm and a maximum spacing of 1-2 mm between units. The SiC@BN core-shell nanowires within each periodic unit are densely packed and do not overlap. The periodic height of the three-dimensional periodic array is 200-400 μm. The Si3N4 ceramic matrix is ​​prepared by chemical vapor infiltration. The Si3N4 ceramic matrix uniformly fills the pores between the SiC@BN core-shell nanowires, with a porosity of 10-20%. The thickness of the Si3N4 ceramic matrix is ​​consistent with the periodic height of the three-dimensional periodic array.

[0012] Furthermore, the method for preparing the SiC@BN core-shell nanowire periodic array-enhanced Si3N4 high-temperature absorbing ceramic coating is characterized by comprising the following steps:

[0013] 1) Prepare a nickel nitrate hexahydrate / ethanol solution of a certain concentration, uniformly coat it on the surface of SiC / SiC composite material, and after thorough impregnation, place it in a drying oven at 40-60℃ to dry at a low temperature until the ethanol is completely evaporated. Place the SiC / SiC composite material with the catalyst impregnated on the surface in a high-temperature tube furnace, evacuate the high-temperature tube furnace and heat it to the reaction temperature, introduce the MTS+H2+Ar reaction source system, set the catalyst concentration to 0.01-0.1mol / L, the reaction temperature to 900-1100℃, the reaction time to 1-2h, the reaction source ratio to MTS:H2:Ar=5:50:50sccm, and the heating rate to 4-5℃ / min to prepare SiC nanowires on the surface of the SiC / SiC composite material;

[0014] 2) Place the SiC / SiC composite material with SiC nanowires on the surface into a high-temperature tube furnace. After evacuating the high-temperature tube furnace, heat it to the reaction temperature and introduce the BCl3+NH3+H2+Ar reaction source system. Set the reaction source ratio BCl3:NH3:H2:Ar=5:7.5:10:50sccm, the reaction temperature is 600-750℃, the heating rate is 5-10℃ / min, and the reaction time is 1-2h to construct a BN shell on the surface of SiC nanowires.

[0015] 3) The electromagnetic parameters of SiC / SiC composite material and SiC@BN core-shell nanowires were characterized using the coaxial method. A periodic structure simulation model with SiC@BN core-shell nanowires as the pattern layer, SiC / SiC composite material as the dielectric layer and metal substrate as the reflective layer was constructed in CST software to determine the microstructure parameters of SiC@BN core-shell nanowires and the macrostructure parameters of the periodic array such as periodic unit and array height.

[0016] 4) According to the preferred scheme in (3), periodic patterns are prepared on graphite paper by laser etching process, and then the graphite paper with periodic patterns is tightly laid on the surface of SiC / SiC composite material. A nickel nitrate hexahydrate / ethanol solution of corresponding concentration is uniformly coated on the surface of graphite paper by printing process. After being fully impregnated, it is placed in a drying oven at 40-60℃ and dried at low temperature until the ethanol is completely evaporated. Then, according to the determined process parameters of SiC nanowires and BN shell, the precise construction of SiC@BN core-shell nanowire periodic array is realized on the surface of SiC / SiC composite material.

[0017] 5) The SiC / SiC composite material with SiC@BN core-shell nanowire periodic arrays on its surface was placed in a high-temperature tube furnace. After the high-temperature tube furnace was evacuated, it was heated to the reaction temperature. The SiCl4+NH3+H2+Ar reaction source system was introduced. The reaction source ratio was set as SiCl4:NH3:H2:Ar=30:80:100:50sccm, the reaction temperature was 700-900℃, the heating rate was 5-10℃ / min, and the reaction time was 1-2h. A Si3N4 ceramic matrix reinforced by SiC@BN core-shell nanowire periodic arrays was obtained on the surface of the SiC / SiC composite material.

[0018] The beneficial effects of this invention are as follows: ① This invention constructs a periodic structure simulation model using CST software, with SiC@BN core-shell nanowires as the pattern layer, SiC / SiC composite material as the dielectric layer, and a metal substrate as the reflective layer. This model determines the microstructural parameters of the SiC@BN core-shell nanowires and the macrostructural parameters of the periodic array, such as the periodic unit and array height. This enables the design of a macro- and micro-scale multi-dimensional structure for SiC@BN core-shell nanowire periodic array-enhanced Si3N4 high-temperature absorbing ceramic coating. ② Through macro- and micro-scale multi-dimensional structural design, the SiC nanowires and BN shell form a core-shell structure. Micro-scale control can introduce lattice distortion, stacking faults, and interface defects, promoting the absorption and attenuation loss of incident electromagnetic waves and improving electromagnetic wave absorption capability. Simultaneously, the SiC@BN core-shell nanowires form a periodic array on the surface of the SiC / SiC composite material. Macro-scale control can introduce surface electric field coupling effects and multiple scattering loss mechanisms, improving the impedance matching characteristics of surface electromagnetic waves, broadening the effective absorption bandwidth, and synergistically enhancing electromagnetic wave absorption characteristics. ③ This invention uses a SiC@BN core-shell nanowire periodic array as a reinforcement and Si3N4 ceramic as a matrix, which can be stably used in high-temperature environments and realize the application of high-temperature wave absorption characteristics. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the fabrication process of the SiC@BN core-shell nanowire periodic array-enhanced Si3N4 high-temperature microwave absorbing ceramic coating in this invention. Detailed Implementation

[0020] 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.

[0021] Example 1

[0022] A SiC@BN core-shell nanowire periodic array-enhanced Si3N4 high-temperature microwave absorbing ceramic coating is composed of SiC nanowires, a BN shell, and a Si3N4 ceramic substrate. The SiC nanowires and BN shell are obtained through a chemical vapor infiltration process, forming a core-shell structure to obtain SiC@BN core-shell nanowires. The SiC nanowires have a diameter of 1 μm, and the BN shell has a thickness of 300 nm. The BN shell is uniformly distributed on the surface of the SiC nanowires, preventing oxidation of the SiC nanowires while improving their dielectric constant, thus increasing electromagnetic wave transmittance by 50%. The SiC@BN core-shell nanowires are arranged in a three-dimensional periodic array. The periodic unit of the three-dimensional periodic array is circular with a size of 8 mm and a maximum spacing of 1.5 mm between the periodic units. The SiC@BN core-shell nanowires within the periodic unit are densely packed and do not overlap. The periodic height of the three-dimensional periodic array is 250 μm. The Si3N4 ceramic matrix is ​​prepared by chemical vapor infiltration. The Si3N4 ceramic matrix uniformly fills the pores between the SiC@BN core-shell nanowires, with a porosity of 15%. The thickness of the Si3N4 ceramic matrix is ​​consistent with the periodic height of the three-dimensional periodic array.

[0023] Furthermore, the method for preparing the SiC@BN core-shell nanowire periodic array-enhanced Si3N4 high-temperature absorbing ceramic coating is characterized by comprising the following steps:

[0024] 1) Prepare a nickel nitrate hexahydrate / ethanol solution of a certain concentration, uniformly coat it on the surface of SiC / SiC composite material, and after thorough impregnation, place it in a 50℃ drying oven to dry at low temperature until the ethanol is completely evaporated. Place the SiC / SiC composite material with the catalyst impregnated on the surface in a high-temperature tube furnace, evacuate the high-temperature tube furnace and heat it to the reaction temperature, introduce the MTS+H2+Ar reaction source system, set the catalyst concentration to 0.05mol / L, the reaction temperature to 1000℃, the reaction time to 1h, the reaction source ratio MTS:H2:Ar=5:50:50sccm, the heating rate to 4℃ / min, and prepare SiC nanowires on the surface of SiC / SiC composite material;

[0025] 2) The SiC / SiC composite material with SiC nanowires on the surface was placed in a high-temperature tube furnace. After the high-temperature tube furnace was evacuated, it was heated to the reaction temperature. The BCl3+NH3+H2+Ar reaction source system was introduced. The reaction source ratio was set as BCl3:NH3:H2:Ar=5:7.5:10:50sccm, the reaction temperature was 650℃, the heating rate was 8℃ / min, and the reaction time was 1h. A BN shell was constructed on the surface of the SiC nanowires.

[0026] 3) The electromagnetic parameters of SiC / SiC composite material and SiC@BN core-shell nanowires were characterized using the coaxial method. A periodic structure simulation model with SiC@BN core-shell nanowires as the pattern layer, SiC / SiC composite material as the dielectric layer and metal substrate as the reflective layer was constructed in CST software to determine the microstructure parameters of SiC@BN core-shell nanowires and the macrostructure parameters of the periodic array such as periodic unit and array height.

[0027] 4) According to the preferred scheme in (3), periodic patterns are prepared on graphite paper by laser etching process, and then the graphite paper with periodic patterns is tightly laid on the surface of SiC / SiC composite material. The corresponding concentration of nickel nitrate hexahydrate / ethanol solution is uniformly coated on the surface of graphite paper by printing process. After being fully impregnated, it is placed in a drying oven at 46°C and dried at low temperature until the ethanol is completely evaporated. Then, according to the determined process parameters of SiC nanowires and BN shell, the precise construction of SiC@BN core-shell nanowire periodic array is realized on the surface of SiC / SiC composite material.

[0028] 5) The SiC / SiC composite material with a SiC@BN core-shell nanowire periodic array on its surface was placed in a high-temperature tube furnace. After the high-temperature tube furnace was evacuated, it was heated to the reaction temperature. The SiCl4+NH3+H2+Ar reaction source system was introduced. The reaction source ratio was set as SiCl4:NH3:H2:Ar=30:80:100:50sccm, the reaction temperature was 790℃, the heating rate was 5℃ / min, and the reaction time was 1h. A Si3N4 ceramic matrix reinforced by a SiC@BN core-shell nanowire periodic array was obtained on the surface of the SiC / SiC composite material.

[0029] The above is merely one specific embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the scope of protection of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A SiC@BN core-shell nanowire periodic array reinforced Si3N4 high-temperature wave-absorbing ceramic coating, which is composed of SiC nanowires, a BN shell layer and a Si3N4 ceramic matrix, characterized in that The SiC nanowire and the BN shell are obtained by a chemical vapor infiltration process, and form a core-shell structure to obtain the SiC@BN core-shell nanowire, the diameter of the SiC nanowire is 1-2 μm, the thickness of the BN shell is 300-400 nm, the BN shell is uniformly distributed on the surface of the SiC nanowire, which avoids oxidation of the SiC nanowire and improves the dielectric constant of the SiC nanowire, so that the transmission rate of electromagnetic waves is increased by 50-70%; the SiC@BN core-shell nanowire is arranged in a three-dimensional periodic array, the periodic unit of the three-dimensional periodic array is one of a circle, a square and a triangle, the periodic unit size is 6-10 mm, the maximum spacing between the periodic units is 1-2 mm, the SiC@BN core-shell nanowires in the periodic unit grow densely and do not overlap with each other, and the periodic height of the three-dimensional periodic array is 200-400 μm; the Si3N4 ceramic matrix is prepared by a chemical vapor infiltration process, the Si3N4 ceramic matrix is uniformly filled in the pores between the SiC@BN core-shell nanowires, the porosity is 10-20%, and the thickness of the Si3N4 ceramic matrix is consistent with the periodic height of the three-dimensional periodic array.

2. A method for preparing the SiC@BN core-shell nanowire periodic array reinforced Si3N4 high-temperature wave-absorbing ceramic coating according to claim 1, characterized in that The method comprises the following steps: 1) a certain concentration of nickel nitrate hexahydrate / ethanol solution is configured and uniformly coated on the surface of the SiC / SiC composite material, and after sufficient immersion, the SiC / SiC composite material with the surface immersed with the catalyst is placed in a low-temperature drying oven at 40-60°C for drying until the ethanol is completely volatilized, the SiC / SiC composite material with the surface immersed with the catalyst is placed in a high-temperature tube furnace, the high-temperature tube furnace is vacuumized, and then heated to a reaction temperature, an MTS+H2+Ar reaction source system is introduced, the catalyst concentration is set to 0.01-0.1 mol / L, the reaction temperature is 900-1100°C, the reaction time is 1-2 h, the reaction source ratio MTS:H2:Ar is 5:50:50 sccm, and the heating rate is 4-5°C / min, so as to prepare SiC nanowires on the surface of the SiC / SiC composite material; 2) the SiC / SiC composite material with the surface prepared with the SiC nanowires is placed in a high-temperature tube furnace, the high-temperature tube furnace is vacuumized, and then heated to a reaction temperature, a BCl3+NH3+H2+Ar reaction source system is introduced, the reaction source ratio BCl3:NH3:H2:Ar is set to 5:7.5:10:50 sccm, the reaction temperature is 600-750°C, the heating rate is 5-10°C / min, and the reaction time is 1-2 h, so as to build a BN shell on the surface of the SiC nanowire; 3) the electromagnetic parameters of the SiC / SiC composite material and the SiC@BN core-shell nanowire are characterized by a coaxial method, a periodic structure simulation model with the SiC@BN core-shell nanowire as a pattern layer, the SiC / SiC composite material as a dielectric layer and a metal bottom plate as a reflection layer is constructed in CST software, and the microstructure parameters of the SiC@BN core-shell nanowire and the macrostructure parameters of the periodic array such as the periodic unit and the array height are determined. 4) Periodic pattern preparation on graphite paper by laser etching process, then the graphite paper printed with periodic pattern is tightly laid on the surface of SiC / SiC composite material, uniform brushing of corresponding concentration of nickel nitrate hexahydrate / ethanol solution on the surface of graphite paper by printing process, after sufficient immersion, placed in 40-60℃ drying oven for low temperature drying until ethanol completely volatilizes, then according to the process parameters of SiC nanowire and BN shell layer, precise construction of SiC@BN core-shell nanowire periodic array on the surface of SiC / SiC composite material is realized; 5) The SiC / SiC composite material with surface constructed SiC@BN core-shell nanowire periodic array is placed in a high temperature tube furnace, after vacuumizing the high temperature tube furnace, heated to reaction temperature, SiCl4+NH3+H2+Ar reaction source system is introduced, the reaction source ratio is set as SiCl4:NH3:H2:Ar=30:80:100:50sccm, the reaction temperature is 700-900℃, the heating rate is 5-10℃ / min, the reaction time is 1-2h, SiC@BN core-shell nanowire periodic array reinforced Si3N4 ceramic matrix is obtained on the surface of SiC / SiC composite material.

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