A pressureless sintering combined with precursor impregnation and pyrolysis for the preparation of 3D C f Method for / zrb2-zrc-sic composite

Abstract

This invention discloses a method for preparing 3D C by pressureless sintering combined with precursor impregnation and pyrolysis. f Method for preparing ZrB2-ZrC-SiC composite materials. (1) Mix ZrSi2, B4C, C, ZrB2, dispersant, anhydrous ethanol and grinding balls, and ball mill; (2) Place the 3D carbon fiber preform in the ball milling slurry, first vacuum impregnate, then impregnate under pressure in an inert atmosphere, remove, and dry. This is one cycle, and the impregnation is repeated multiple times to obtain the preform; (3) Sinter the preform under pressureless vacuum to obtain 3D C f / ZrB2-SiC preform; (4) 3D C f The ZrB2-SiC preform was immersed in a ZrC ceramic precursor solution and PIPed multiple times, followed by high-temperature treatment in a vacuum environment to obtain 3D C. f / ZrB2-ZrC-SiC composite material. This invention achieves the preparation of composite materials at relatively low temperatures through pressureless sintering combined with precursor impregnation and pyrolysis processes, solving the problem of 3D C f The high preparation temperature of UHTCs-SiC composite materials; fewer preparation cycles compared to the single PIP process; this invention's 3D C f / ZrB2-ZrC-SiC has excellent ablation resistance.

Description

Technical Field

[0001] This invention belongs to the field of ceramic matrix composite material preparation technology, and specifically relates to a method for preparing 3D C by impregnation and pyrolysis of a pressureless sintering-bonded precursor. f Methods for creating ZrB2-ZrC-SiC composite materials. Background Technology

[0002] New-generation high-Mach number aerospace vehicles will face extreme aerodynamic heating and mechanical erosion coupling effects exceeding 2000°C for thousands of seconds during atmospheric reentry, particularly on key components such as the nose cone and wing leading edge. This necessitates a long-lasting, reusable thermal protection system. Therefore, developing novel high-temperature thermal protection structural materials with excellent properties such as lightweight, high strength and toughness, and resistance to long-term ablation is of great significance.

[0003] UHTCs-SiC multiphase ceramic systems, with their excellent high-temperature stability and ablation resistance, have become a promising candidate material system for aerospace thermal protection. However, the inherent brittleness of ceramic materials limits their reliability in engineering applications. Introducing carbon fibers into ceramic matrix composites can effectively improve the brittle characteristics and fracture behavior of the ceramic matrix; therefore, C... f / UHTCs-SiC composite materials have attracted widespread attention from researchers both domestically and internationally. Existing C f The preparation techniques for UHTCs-SiC mainly include precursor impregnation pyrolysis (PIP), hot pressing sintering (HP), and reactive melt infiltration (RMI). Each of these methods has its own characteristics and plays an important role in the preparation of this material system. The PIP process has a relatively low preparation temperature, effectively reducing fiber thermal damage and showing a significant advantage in preparing high-purity ceramic matrices. However, this method has a long preparation cycle and is affected by precursor pyrolysis shrinkage, easily leaving many pores in the composite material. The HP process is relatively simple, with easily controllable composition, and can obtain materials with high density. However, the sintering temperature is relatively high, easily causing severe thermal damage to the reinforcing fibers. The RMI method has a short preparation cycle and high densification efficiency, producing composite materials with high surface density and almost no residual pores. However, the melt easily erodes the fibers and easily leaves low-melting-point phases, thus reducing the high-temperature performance of the material. In summary, each of the mainstream processes such as PIP, HP, and RMI has its advantages and disadvantages in preparing ultra-high temperature ceramic matrix composites, and none can simultaneously achieve low-temperature preparation, precise composition control, and a short preparation cycle. Therefore, C, which combines the characteristics of pure phase, low temperature, and short period, f The development of preparation processes for UHTCs-SiC composite materials is particularly important. Summary of the Invention

[0004] To solve the existing C fThe preparation of UHTCs-SiC composite materials cannot simultaneously achieve pure phase, low temperature, and short cycle. The purpose of this invention is to provide a pressureless sintering method combined with precursor impregnation and pyrolysis for the preparation of 3D C. f Methods for creating ZrB2-ZrC-SiC composite materials.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A pressureless sintering combined with precursor impregnation and pyrolysis preparation of 3D C f / ZrB2-ZrC-SiC composite material (3D C) f The method (abbreviation for three-dimensional carbon fiber) involves the following preparation steps: (1) Prepare raw materials: Weigh out four raw material powders: ZrSi2, B4C, C, and ZrB2, as well as a dispersant; wherein, in molar ratio, ZrSi2∶B4C∶C∶ZrB2=2∶(1~1.05)∶(3~3.15)∶(4.40~8.98); the amount of dispersant used is 2~3% of the total mass of the four raw material powders; (2) Preparation of ball milling slurry: (2.1) Mix the dispersant and anhydrous ethanol 1# evenly to obtain a dispersant solution; wherein, the ratio of dispersant to anhydrous ethanol 1# is 6.3g to (140~280)mL. (2.2) Add the four raw material powders weighed in step (1), anhydrous ethanol #2, and grinding balls into the ball mill jar, and then add the dispersant solution prepared in step (2.1) for ball milling; after ball milling is completed, separate the ball mill slurry from the grinding balls; wherein, the mass ratio of grinding balls to the total mass of the four raw material powders is (4~5) g: 1 g, and the mass ratio of the total mass of the four raw material powders to anhydrous ethanol #2 is 210 g: (770~910) mL; (3) Preparation of preform by mud impregnation method: The 3D carbon fiber preform is placed in the ball mill slurry obtained in step (2.2), first vacuum impregnated for 10~30min, then impregnated under pressure of 0.2~0.25MPa in an inert atmosphere for 10~30min. After impregnation, the 3D carbon fiber preform is taken out and vacuum dried. This is one cycle. The impregnation is repeated multiple times to obtain the preform. (4) Preparation of C by pressureless sintering f / ZrB2-SiC preform: The preform obtained in step (3) was subjected to pressureless sintering in a vacuum environment: sintering temperature 1600~1800℃, holding time 1~2h; after sintering, it was cooled to room temperature to obtain 3D C. f / ZrB2-SiC preform; (5) Preparation of 3D C by precursor impregnation-curing-pyrolysisf / ZrB2-ZrC-SiC composite material: (5.1) Take the 3D C obtained in step (4) f The ZrB2-SiC preform is placed in a ZrC ceramic precursor solution, and then vacuum impregnated in an impregnation device for 10-30 min, followed by pressure impregnation at 0.2-0.25 MPa under an inert atmosphere for 10-30 min. (5.2) After impregnation, the sample is taken out and cured and pyrolyzed in an inert atmosphere: the temperature is raised from room temperature to the curing temperature of 150~200℃ and held for 2~4h, and then the temperature is raised to the pyrolysis temperature of 1100~1300℃ and held for 2~4h; after the pyrolysis is completed, the sample is cooled to room temperature. (5.3) Repeat steps (5.1) and (5.2) for at least 3 cycles, with step (5.1)-step (5.2) as one cycle; (5.4) The sample obtained in step (5.3) is subjected to high-temperature treatment in a vacuum environment: the high-temperature treatment temperature is 1600~1700℃ and the holding time is 2~4h; after the high-temperature treatment, it is cooled to room temperature to obtain 3D C. f / ZrB2-ZrC-SiC composite material.

[0006] Preferably, in step (1), the dispersant is polyethyleneimine.

[0007] Preferably, in step (2.2), the grinding ball is composed of a large grinding ball and a small grinding ball, the diameter of the large grinding ball is 9.5~10.5mm, and the diameter of the small grinding ball is 5.5~6.5mm; in terms of mass ratio, the ratio of large grinding ball to small grinding ball is 1: (3~5).

[0008] Preferably, in step (2.2), the ball mill speed is 450~650 rpm and the ball milling time is 8~16 h.

[0009] Preferably, in step (3), the number of cyclic impregnations is 6 to 8.

[0010] Preferably, in steps (3), (5.1) and (5.2), the inert atmosphere is argon.

[0011] In step (5.1), the ZrC ceramic precursor solution can be any fluid precursor solution whose pyrolysis product is ZrC. Preferably, but not limited to, the ZrC ceramic precursor solution is formed by mixing ZrC ceramic precursor and solvent, the concentration of ZrC ceramic precursor in the ZrC ceramic precursor solution is 10~80wt% (preferably 20~70wt%), and the solvent is an alcohol solvent, DMF or DMSO.

[0012] Preferably, in step (5.1), the alcohol solvent is n-propanol or n-butanol.

[0013] Preferably, in step (5.2), the temperature is increased to the curing temperature at a rate of 1~3℃ / min, and to the pyrolysis temperature at a rate of 3~5℃ / min.

[0014] Preferably, in steps (4), (5.2) and (5.4), during cooling, the temperature is first reduced to 200-300°C at a rate of 5-8°C / min, and then naturally cooled to room temperature.

[0015] In this invention, the 3D carbon fiber preform (three-dimensional carbon fiber preform with a fiber volume fraction of 8~12%) and the ZrC ceramic precursor are known products (which can be solid or liquid) and can be obtained commercially or prepared by referring to existing technologies; wherein, the preparation technology of the ZrC ceramic precursor includes, but is not limited to, the method disclosed in CN201911239788.0.

[0016] Principle of this invention: This invention mainly utilizes the reaction formula: 2ZrSi2 + B4C + 3C = 2ZrB2 + 4SiC, in which ZrB2 and SiC are generated in situ during sintering. Simultaneously, to control the C content after sintering... f The volume fraction of SiC in the ZrB2-SiC preform is adjusted by adding an additional ZrB2 content. Through experimentation, the present invention finally determined the raw material molar ratio to be ZrSi2∶B4C∶C∶ZrB2=2∶(1~1.05)∶(3~3.15)∶(4.40~8.98).

[0017] Beneficial effects: (1) This invention achieves 3D C by combining pressureless sintering with precursor impregnation and pyrolysis process at a relatively low temperature of 1600~1700℃. f The manufacturing of ZrB2-ZrC-SiC has solved the problem of 3D C f The high preparation temperature of the UHTCs-SiC composite system causes severe fiber damage and abnormal grain growth in the matrix, among other key issues. (2) The composite material prepared by the present invention has a shorter preparation cycle than the single PIP process, which can alleviate the problems of stronger fiber / matrix interface bonding and intensified interface reaction caused by excessively long PIP cycle. (3) This invention is designed for the extreme service requirements of thermal protection materials. Under the harsh conditions of the highest temperature exceeding 2450℃ and continuous ablation for 600s, the composite material density is increased and the response differences and synergistic mechanisms of ZrB2, ZrC and SiC during the ablation process are used to promote the formation of a continuous, dense and stable ablation protection layer on the material surface, thereby significantly improving its long-term ablation resistance performance. Attached Figure Description

[0018] Figure 1 The 3D C obtained in Example 1 f XRD pattern of ZrB2-SiC preform.

[0019] Figure 2 The 3D C obtained in Example 1 f XRD patterns of the ZrB2-SiC preform before (a) and after (b) high-temperature treatment after three PIP cycles; wherein, the sample before high-temperature treatment corresponds to the sample obtained in step (5.3) of Example 1, and the sample after high-temperature treatment corresponds to the final product PIP-3 prepared in step (5.4) of Example 1.

[0020] Figure 3 The ablation resistance test time-temperature curves for PIP-0 after 300s ablation, and for PIP-3 after 300s and 600s ablation.

[0021] Figure 4 Optical photographs taken after PIP-0 ablation for 300s, PIP-3 ablation for 300s, and PIP-3 ablation for 600s, and then cooled to room temperature.

[0022] Figure 5 The XRD patterns of the materials after PIP-0 ablation for 300s, PIP-3 ablation for 300s, and 600s are shown. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0024] In the following embodiments, the raw material 3D carbon fiber preform (three-dimensional carbon fiber preform) in step (3) was purchased from Jiangsu Tianniao High-Tech Co., Ltd., with a fiber volume fraction of about 10% and a porosity of about 90%; the ZrC ceramic precursor solution (model HFT64032) was purchased from Beijing Huawi Ruike Chemical Technology Co., Ltd.

[0025] Example 1

[0026] A pressureless sintering combined with precursor impregnation and pyrolysis preparation of 3D C f The method for producing ZrB2-ZrC-SiC composite materials includes the following steps: (1) Prepare raw materials: As shown in Table 1, weigh out four raw material powders: ZrSi2 (zirconium disilicide), B4C (boron carbide), C (activated carbon), and ZrB2 (zirconium diboride), as well as the dispersant PEI (polyethyleneimine). ; (2) Preparation of ball milling slurry: (2.1) Weigh the PEI and 140 mL of anhydrous ethanol in step (1), stir for 10 min to obtain a PEI solution; (2.2) Add the four raw material powders ZrSi2, B4C, C and ZrB2 weighed in step (1), 840g of zirconia grinding balls (of which, the large grinding ball with a diameter of 10mm weighs 210g and the small grinding ball with a diameter of 6mm weighs 630g) and 770mL of anhydrous ethanol into the ball mill jar, and then add the PEI solution prepared in step (2.1). Place the ball mill jar in the ball mill and ball mill at 650rpm for 12h. After the ball milling is completed, separate the ball mill slurry from the grinding balls. (3) Preparation of preform by mud impregnation method: In the impregnation equipment, the 3D carbon fiber preform is placed horizontally in the ball mill slurry obtained in step (2.2), and then the impregnation equipment chamber is sealed and vacuum operation is performed. Vacuum impregnation is performed for 10 minutes. After vacuum impregnation, argon gas is slowly introduced into the chamber and the pressure is slowly increased to 0.25 MPa under argon atmosphere. Pressure is maintained for 10 minutes. The 3D carbon fiber preform is taken out and vacuum drying is one cycle. The cycle is repeated 7 times to obtain the preform. (4) Preparation of 3D C by pressureless sintering f / ZrB2-SiC preform: The preform obtained in step (3) was subjected to pressureless sintering in a vacuum environment: held at 1700℃ for 1 hour; after sintering, the temperature was first reduced to 300℃ at a rate of 5℃ / min, and then naturally cooled to room temperature to obtain 3D C. f / ZrB2-SiC preform, marked as PIP-0; (5) Preparation of 3D C by precursor impregnation-curing-pyrolysis (PIP) f / ZrB2-ZrC-SiC composite material: (5.1) In the impregnation equipment, the 3D C obtained in step (4) is placed... fThe ZrB2-SiC preform is immersed in the ZrC ceramic precursor solution, and then the impregnation equipment chamber is sealed and a vacuum operation is performed. Vacuum impregnation is performed for 30 minutes. After vacuum impregnation, argon gas is slowly introduced into the chamber and the pressure is slowly increased to 0.25 MPa under the argon atmosphere. The pressure is maintained for 30 minutes. (5.2) After impregnation, the sample is taken out and placed in a tube furnace for curing and pyrolysis in an argon atmosphere: the temperature is increased from room temperature to the curing temperature of 180℃ at a rate of 3℃ / min and held for 3h, and then increased to the pyrolysis temperature of 1200℃ at a rate of 5℃ / min and held for 2h; after pyrolysis, the temperature is first reduced to 300℃ at a rate of 5℃ / min, and then naturally cooled to room temperature. (5.3) Repeat steps (5.1) and (5.2) for a total of 3 cycles, with step (5.1)-step (5.2) as one cycle; (5.4) The sample obtained in step (5.3) is subjected to high-temperature treatment in a vacuum environment: held at 1600℃ for 2 hours; after the high-temperature treatment, the temperature is first reduced to 300℃ at a rate of 5℃ / min, and then naturally cooled to room temperature to obtain 3D C. f / ZrB2-ZrC-SiC composite material, designated as PIP-3.

[0027] Structural characterization Figure 1 The 3D C obtained in Example 1 f XRD pattern of the ZrB2-SiC preform. Figure 1 It can be seen that the phase composition of the preform after pressureless sintering includes ZrB2 and SiC. No diffraction peaks of ZrSi2, B4C, and C were detected, indicating that ZrSi2, B4C, and C underwent a chemical reaction according to "2ZrSi2 + B4C + 3C = 2ZrB2 + 4SiC" during the pressureless sintering process, producing ZrB2 and SiC, thus achieving precise control of the preform phase.

[0028] 2 is the 3D C obtained in Example 1. f XRD patterns of the ZrB2-SiC preform before (a) and after (b) high-temperature treatment after three PIP cycles; the sample before high-temperature treatment corresponds to the sample obtained in step (5.3) of Example 1, and the sample after high-temperature treatment corresponds to the final product PIP-3 prepared in step (5.4) of Example 1. During the PIP cycle, the pyrolysis temperature was 1200℃. Figure 2 (a) shows that the phase composition of the densified preform is mainly ZrB2 and ZrO2 (the O in ZrO2 originates from the oxygen-containing functional groups in the ZrC ceramic precursor), and no ZrC phase was detected, indicating that the ZrC precursor did not transform into the ZrC phase at this temperature. Figure 2(b) It can be seen that after treatment at 1600℃ for 2 hours, the phase composition of the composite material includes ZrB2 and ZrC, while the ZrO2 phase disappears and transforms into ZrC. This is because a carbothermic reduction reaction occurred at high temperature. Furthermore, Figure 2 (b) shows a weak diffraction peak detected at 2θ = ~36° on the XRD pattern, which is attributed to β -SiC, possibly because SiC has poor crystallinity; Figure 2 (b) The XRD pattern did not show diffraction peaks for carbon fibers. The reason for this is that the diffraction peaks of carbon fibers are weak and broad, and their crystallinity is low, while the ZrB2-ZrC matrix has good crystallinity. Therefore, the diffraction peaks of the carbon fibers are masked by the diffraction peaks of the ZrB2-ZrC matrix. From the above analysis, it can be seen that 3D carbon fiber can be achieved using a PIP cycle combined with high-temperature processing. f Low-temperature controllable fabrication and precise regulation of phase composition of ZrB2-ZrC-SiC composite materials.

[0029] ablation resistance test The PIP-0 and PIP-3 samples obtained in Example 1 were respectively made into disc-shaped samples with a cross-sectional diameter of 30 mm, and then their ablation resistance was tested under an oxyacetylene flame: oxygen pressure was 0.45 MPa, acetylene pressure was 0.12 MPa, and oxygen flow rate was approximately 3.175 m³ / h. 3 / h, the acetylene flow rate is approximately 2.343 m³ / h. 3 / h, heat flux density approximately 9.7MW / m 2 The ablation nozzle diameter is 3.0 mm, the flame nozzle is vertically facing the center of the sample and 15 mm away from the sample surface, and the ablation time is set to 300 s and 600 s.

[0030] Figure 3 The ablation resistance test time-temperature curves are shown for PIP-0 after 300s, and PIP-3 after 300s and 600s. Figure 3 It can be seen that when PIP-0 is ablated for 300s, PIP-3 is ablated for 300s and 600s, the stable temperature of the corresponding material surface is above 2450℃.

[0031] The mass ablation rate and linear ablation rate of PIP-0 and PIP-3 are shown in Table 2. Among them, the mass ablation rate of the samples ( M A ) and line ablation rate ( L A Calculate according to formulas (1) and (2) respectively: ; In the formula: M A The mass ablation rate; m bThe mass of the sample before ablation; m a The mass of the sample after ablation; t This refers to the ablation time. L A Linear ablation rate; l b The thickness of the sample before ablation; l a This represents the thickness of the central region of the sample after ablation.

[0032]

[0033] Table 2 shows that the 3D C obtained after high-temperature treatment following 3 PIP cycles f The mass ablation rate and linear ablation rate of the ZrB2-ZrC-SiC composite material (PIP-3) after 300s ablation were -0.216mg / s and -1.987μm / s, respectively. The ablation resistance was significantly improved compared with that of the same ablation time (PIP-0). The reasons are: (1) PIP cycling can significantly reduce the porosity of the material, and the relatively dense structure can slow down the erosion of carbon fibers by oxyacetylene flame; (2) 3D C obtained by high-temperature treatment after PIP cycling. f The ZrB2-ZrC-SiC composite material (PIP-3) contains both ultra-high temperature carbides and ultra-high temperature borides. Their different ablation response behaviors and synergistic effects with SiC promote the formation of a continuous, dense, and stable ablation layer on the surface, protecting the internal material. Furthermore, after 600 s of ablation, PIP-3 exhibits positive mass ablation rate and linear ablation rate, due to the appearance of ablation pits on the surface with prolonged ablation time. However, the mass ablation rate and linear ablation rate of PIP-3 after 600 s are still lower than those of PIP-0 after 300 s, indicating that the relatively dense structure plays a positive role in improving ablation resistance.

[0034] Figure 4 Optical photographs taken after PIP-0 ablation for 300 s, PIP-3 ablation for 300 s, and PIP-3 ablation for 600 s, followed by cooling to room temperature. Figure 4 It can be seen that although the surface of PIP-0 was covered with ablation products after 300s of ablation, there were obvious ablation pits. This indicates that the relatively loose structure prevented the ablation products from being effectively retained on the surface. Furthermore, the ablation products on the surface exhibited a flocculent porous structure, which could not protect the internal material and could not meet the requirements for long-term ablation, resulting in a high linear ablation rate. In contrast, the 3D C obtained after high-temperature treatment following three PIP cycles... fAfter 300 s of ablation, the surface of the ZrB2-ZrC-SiC composite material (PIP-3) was covered with ablation products, and no ablation pits were observed. The ablation products formed can play a role in inhibiting oxyacetylene flame erosion. When the ablation time was extended to 600 s, ablation pits were observed on the surface of the composite material, but the depth of the ablation pits was significantly lower than that of PIP-0. Therefore, the linear ablation rate and mass ablation rate were lower than those of PIP-0. This indicates that the relatively dense structure after PIP cycles and the response differences and synergistic mechanisms of ZrB2, ZrC, and SiC during the ablation process can significantly improve the long-term ablation resistance of the composite material.

[0035] Figure 5 The XRD patterns of the materials after 300s of PIP-0 ablation, 300s of PIP-3 ablation, and 600s of PIP-3 ablation are shown. Figure 5 It can be seen that after PIP-0 ablation for 300s, PIP-3 ablation for 300s and 600s, the surface of the corresponding materials is mainly composed of ZrO2, and no composite matrix phase is detected. This indicates that the composite matrix on the surface has been oxidized and covered by ablation products. Since ZrO2 is prone to phase transformation leading to volume expansion, the linear ablation rate value of PIP-3 after 300s ablation is negative.

Claims

1. A method for preparing 3D C by pressureless sintering combined with precursor impregnation and pyrolysis. f The method for producing ZrB2-ZrC-SiC composite materials is characterized by... The preparation steps are as follows: (1) Prepare raw materials: Weigh out four raw material powders: ZrSi2, B4C, C, and ZrB2, as well as a dispersant; wherein, in molar ratio, ZrSi2∶B4C∶C∶ZrB2=2∶(1~1.05)∶(3~3.15)∶(4.40~8.98); the amount of dispersant used is 2~3% of the total mass of the four raw material powders; (2) Preparation of ball milling slurry: (2.1) Mix the dispersant and anhydrous ethanol 1# evenly to obtain a dispersant solution; wherein, the ratio of dispersant to anhydrous ethanol 1# is 6.3g to (140~280)mL. (2.2) Add the four raw material powders weighed in step (1), anhydrous ethanol #2, and grinding balls into the ball mill jar, and then add the dispersant solution prepared in step (2.1) for ball milling; after ball milling is completed, separate the ball mill slurry from the grinding balls; wherein, the mass ratio of grinding balls to the total mass of the four raw material powders is (4~5) g: 1 g, and the mass ratio of the total mass of the four raw material powders to anhydrous ethanol #2 is 210 g: (770~910) mL; (3) Preparation of preform by mud impregnation method: The 3D carbon fiber preform is placed in the ball mill slurry obtained in step (2.2), first vacuum impregnated for 10~30min, then impregnated under pressure of 0.2~0.25MPa in an inert atmosphere for 10~30min. After impregnation, the 3D carbon fiber preform is taken out and vacuum dried. This is one cycle. The impregnation is repeated multiple times to obtain the preform. (4) Preparation of C by pressureless sintering f / ZrB2-SiC preform: The preform obtained in step (3) was subjected to pressureless sintering in a vacuum environment: sintering temperature 1600~1800℃, holding time 1~2h; after sintering, it was cooled to room temperature to obtain 3D C. f / ZrB2-SiC preform; (5) Preparation of 3D C by precursor impregnation-curing-pyrolysis f / ZrB2-ZrC-SiC composite material: (5.1) Take the 3D C obtained in step (4) f The ZrB2-SiC preform is placed in a ZrC ceramic precursor solution, and then vacuum impregnated in an impregnation device for 10-30 min, followed by pressure impregnation at 0.2-0.25 MPa under an inert atmosphere for 10-30 min. (5.2) After impregnation, the sample is taken out and cured and pyrolyzed in an inert atmosphere: the temperature is raised from room temperature to the curing temperature of 150~200℃ and held for 2~4h, and then the temperature is raised to the pyrolysis temperature of 1100~1300℃ and held for 2~4h; after the pyrolysis is completed, the sample is cooled to room temperature. (5.3) Repeat steps (5.1) and (5.2) for at least 3 cycles, with step (5.1)-step (5.2) as one cycle; (5.4) The sample obtained in step (5.3) is subjected to high-temperature treatment in a vacuum environment: the high-temperature treatment temperature is 1600~1700℃ and the holding time is 2~4h; after the high-temperature treatment, it is cooled to room temperature to obtain 3D C. f / ZrB2-ZrC-SiC composite material.

2. The preparation of 3D C by pressureless sintering combined with precursor impregnation and pyrolysis as described in claim 1 f The method for producing ZrB2-ZrC-SiC composite materials is characterized by: In step (1), the dispersant is polyethyleneimine.

3. The preparation of 3D C by pressureless sintering combined with precursor impregnation and pyrolysis as described in claim 1 f The method for producing ZrB2-ZrC-SiC composite materials is characterized by... In step (2.2): the grinding balls consist of large grinding balls and small grinding balls, the diameter of the large grinding balls is 9.5~10.5mm, and the diameter of the small grinding balls is 5.5~6.5mm; the mass ratio of large grinding balls to small grinding balls is 1:(3~5); the rotation speed of the ball mill is 450~650rpm, and the ball milling time is 8~16h.

4. Preparation of 3D C by pressureless sintering combined with precursor impregnation and pyrolysis as described in claim 1 f The method for producing ZrB2-ZrC-SiC composite materials is characterized by: In step (3), the cyclic immersion is repeated 6 to 8 times.

5. The preparation of 3D C by pressureless sintering combined with precursor impregnation and pyrolysis as described in claim 1 f The method for producing ZrB2-ZrC-SiC composite materials is characterized by: In step (5.1), the ZrC ceramic precursor solution is formed by mixing ZrC ceramic precursor and solvent, and the concentration of ZrC ceramic precursor in the ZrC ceramic precursor solution is 10~80wt%; the solvent is an alcohol solvent, DMF or DMSO.

6. The preparation of 3D C by pressureless sintering combined with precursor impregnation and pyrolysis as described in claim 5 f The method for producing ZrB2-ZrC-SiC composite materials is characterized by: In step (5.1), the concentration of the ZrC ceramic precursor in the ZrC ceramic precursor solution is 20~70wt%, and the alcohol solvent is n-propanol or n-butanol.

7. The preparation of 3D C by pressureless sintering combined with precursor impregnation and pyrolysis as described in claim 1 f The method for producing ZrB2-ZrC-SiC composite materials is characterized by: In step (5.2), the temperature is increased to the curing temperature at a rate of 1~3℃ / min, and to the pyrolysis temperature at a rate of 3~5℃ / min.

8. The preparation of 3D C by pressureless sintering combined with precursor impregnation and pyrolysis as described in claim 1 f The method for producing ZrB2-ZrC-SiC composite materials is characterized by: In steps (4), (5.2) and (5.4), during cooling, the temperature is first reduced to 200-300℃ at a rate of 5-8℃ / min, and then naturally cooled to room temperature.

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