A rapid preparation method for ultra-high temperature ceramics and copper compound modified C / C composites

Abstract

The present invention discloses a rapid preparation method of ultra-high temperature ceramics and copper compound modified C / C composites. The composites are composed of ultra-high temperature ceramics, copper compounds, pyrolytic carbon and carbon fiber reinforcements. The preparation method includes the following steps: (1) Using ultra-high temperature ceramic powder and carbon fiber as raw materials, an ultra-high temperature ceramic powder modified carbon fiber preform is prepared by a method of mixing and weaving the powder with the carbon fiber preform; (2) The ultra-high temperature ceramic powder modified carbon fiber preform is placed in a chemical vapor deposition furnace for pyrolytic carbon chemical vapor densification treatment; (3) Low-vacuum reactive infiltration of the ultra-high temperature ceramic modified C / C porous body; (4) Subsequently, the temperature is raised to the infiltration temperature point for ultra-high temperature pressure reactive infiltration, and infiltration is carried out while maintaining the temperature and pressure. The ultra-high temperature ceramics and copper compound modified C / C composites obtained by the present invention have a density of 2.85 to 3.7 g / cm<supgt;3< / supgt>; they have a high ceramic content, a high material density, a low open porosity, and have good high-temperature ablation resistance and erosion resistance.

Description

Technical Field

[0001] The present invention relates to a preparation method of ultra-high temperature ceramics and copper compound modified C / C composites Background Art

[0002] With the rapid development of the new generation of hypersonic weapons, the flight speed of the new generation of cutting-edge weapons is getting faster and faster. In the future, for the thermal structure components of the new generation of aircraft, such as combustion chambers, nose cones, throat liners, etc., in the environment of high heat flux and high flow rate of gas scouring, the service temperature will exceed 3000 °C, which puts higher requirements on the ablation resistance of the new generation of lightweight high-temperature thermal structure materials. Refractory metals and their alloys generally have relatively high densities (10.2 - 19.35 g / cm 3 ), making it difficult to meet the lightweight requirements; ultra-high temperature ceramics have the disadvantages of poor thermal shock resistance and easy fragmentation; C / SiC composites will undergo active oxidation at temperatures above 1650 °C, and the ablation rate will increase sharply; C / C composites are prone to oxidation failure in a high-temperature oxidizing atmosphere. Therefore, the above materials are all difficult to meet the ablation protection requirements of the new generation of lightweight high-temperature thermal structure materials in an ultra-high temperature environment, and new lightweight ablative thermal structure materials must be developed.

[0003] To improve the high-temperature ablation resistance of C / C composites, the ultra-high temperature ceramic matrix modification process is usually adopted to introduce ultra-high temperature ceramic phases into the C / C matrix, which can effectively improve the high-temperature oxidation and ablation resistance of the material. Since the ultra-high temperature ceramic phase can form a molten protective film with a certain viscosity on the material surface during the ablation process, it plays an oxygen barrier and heat insulation effect similar to that of a thermal barrier coating, effectively improving the high-temperature ablation resistance of C / C materials. Copper and its compounds have a high latent heat of fusion. By utilizing their sweating and cooling effect, copper and its compounds are introduced into the ultra-high temperature ceramic modified C / C composites to prepare a new type of ultra-high temperature ceramic and copper compound modified C / C composites, which is expected to further improve the high-temperature ablation resistance of the ultra-high temperature ceramic modified C / C composites. At present, the developed processes for ultra-high temperature ceramic modified C / C composites mainly include precursor infiltration-pyrolysis, chemical vapor infiltration, and high-temperature reactive infiltration, etc. The precursor infiltration-pyrolysis and chemical vapor infiltration processes generally have the disadvantages of long preparation cycle and high cost, and it is difficult to realize the rapid preparation and application promotion of ultra-high temperature ceramic and copper compound modified C / C composites. Although the high-temperature reactive infiltration technology has the advantages of low cost and short cycle, in the actual infiltration process, due to the high viscosity and poor permeability of zirconium or hafnium-based melts, they are extremely easy to react with the surface carbon to form a carbide ceramic matrix at high temperatures. Therefore, it is difficult to achieve uniform reactive infiltration of C / C porous bodies, resulting in problems of low density and high open porosity (≥10%) of the prepared materials. The density and open porosity of the infiltrated materials will have an important impact on the high-temperature ablation resistance of the materials. On the one hand, the material density is directly related to the content of ultra-high temperature ceramic phases in the matrix. When the content of ultra-high temperature ceramics in the matrix is relatively high, the material is more likely to obtain a higher density, and a continuous protective film is easily formed on the surface during the ablation process, which is beneficial to the improvement of ablation performance. On the other hand, the pores will become the diffusion and invasion channels of oxygen during the ablation process, which will further exacerbate the ablation of the material. Therefore, how to realize the rapid preparation of ultra-high temperature ceramic and copper compound modified C / C composites, while increasing their density and reducing their open porosity, is a difficult problem that must be solved during their engineering application process.

[0004] To solve the problem of rapid preparation of ultra-high temperature ceramics and copper compound modified C / C composites, further increase the content of ultra-high temperature ceramic phase and the density of the material after infiltration, and reduce its open porosity, this patent invents a rapid preparation method for ultra-high temperature ceramics and copper compound modified C / C composites. The composite material mainly consists of ultra-high temperature ceramics, copper compounds, pyrolytic carbon, and carbon fiber reinforcement. Among them, the ultra-high temperature ceramic matrix plays the role of an ablation-resistant skeleton, the copper compound plays the role of sweating and cooling, and the carbon fiber plays the role of reinforcement. Since the ultra-high temperature ceramic matrix in the composite material prepared by this invention is mainly composed of ceramic powder and ceramic phase formed by infiltration reaction, the content of ultra-high temperature ceramic phase in it is further increased compared with that in the material prepared by a single infiltration reaction process. At the same time, to solve the sealing hole effect caused by different melt viscosities during the infiltration process, by designing the proportion of high and low viscosity melts in the infiltration material and aiming at the infiltration characteristics of high and low viscosity melts, a two-step infiltration process of low-vacuum reaction infiltration and ultra-high temperature pressure reaction infiltration is invented, thus effectively increasing the density of the material and reducing the open porosity of the material. The ultra-high temperature ceramics and copper compound modified C / C composites prepared by this process have the characteristics of high density (2.85 - 3.7 g / cm 3 ), low open porosity (<8%), and high content of ultra-high temperature ceramic phase, which is beneficial to further improving the gas erosion resistance and ablation resistance of the material, and provides a new way for the rapid and low-cost preparation of ultra-high temperature ceramics and copper compound modified C / C composites. Summary of the Invention

[0005] The present invention provides a rapid preparation method for ultra-high temperature ceramics and copper compound modified C / C composites. By designing the proportion of high and low viscosity melts in the infiltration material and aiming at the infiltration characteristics of high and low viscosity melts, the present invention invents a two-step infiltration process of low-vacuum reaction infiltration and ultra-high temperature pressure reaction infiltration, solves the problems of low cost and rapid preparation of ultra-high temperature ceramics and copper compound modified C / C composites, and effectively increases the density of the material and reduces the open porosity of the material. This material combines the excellent ablation resistance of ultra-high temperature ceramics and the advantage of sweating and cooling of copper compounds. Moreover, since the ultra-high temperature ceramic matrix is mainly composed of ceramic powder and ceramic phase formed by infiltration reaction, the content of ablation-resistant phase is higher, and the obtained material system further improves the high-temperature ablation resistance of ultra-high temperature ceramic modified C / C composites.

[0006] The rapid preparation method for ultra-high temperature ceramics and copper compound modified C / C composites proposed by the present invention, the composite material consists of ultra-high temperature ceramics, copper compounds, pyrolytic carbon, and carbon fiber reinforcement.

[0007] The rapid preparation method for ultra-high temperature ceramics and copper compound modified C / C composites includes the following steps:

[0008] (1) Preparation of ultra-high temperature ceramic powder modified carbon fiber preform: Using ultra-high temperature ceramic powder and carbon fiber as raw materials, an ultra-high temperature ceramic powder modified carbon fiber preform is prepared by the method of mixing and weaving the powder with the carbon fiber preform. The specific process is as follows: One layer of carbon fiber cloth is sandwiched with one layer of web stock, and the fiber web stock and carbon fiber cloth are alternately stacked and laid in sequence. During the laying process, the ultra-high temperature ceramic powder is evenly dispersed in each layer of web stock, and then the web stock layer containing ceramic powder and the fiber cloth are connected into a whole by needling or piercing. After introducing carbon fiber in the thickness direction, the ultra-high temperature ceramic powder modified carbon fiber preform is obtained.

[0009] (2) Pyrolytic carbon matrix densification: The ultra-high temperature ceramic powder modified carbon fiber preform prepared in (1) is put into a chemical vapor deposition furnace for pyrolytic carbon chemical vapor densification treatment to obtain an ultra-high temperature ceramic modified C / C porous body.

[0010] (3) Low-vacuum reactive infiltration: The ultra-high temperature ceramic modified C / C porous body prepared in (2) is machined, ultrasonically cleaned and dried, then the above-mentioned porous body is placed in the infiltration powder, and they are put into a graphite crucible together. Subsequently, the graphite crucible containing the porous body and the infiltration powder is put into a pressure infiltration furnace, and low-vacuum reactive infiltration is carried out after heating to the predetermined temperature.

[0011] (4) Ultra-high temperature pressure reactive infiltration: After the low-vacuum reactive infiltration process in (3) ends, argon is filled for pressurization, and then the temperature is raised to the pressure infiltration temperature point at a higher temperature for the second-stage high-temperature and high-pressure reactive infiltration. After heat preservation and pressure infiltration for a certain time, it is naturally cooled and sampled.

[0012] The density of the ultra-high temperature ceramic and copper compound modified C / C composite material obtained by the present invention is 2.85 - 3.7 g / cm 3 ; by volume percentage, it includes the following components: the carbon fiber content is 15 - 45 vol%, the pyrolytic carbon content is 15 - 35 vol%, the ultra-high temperature ceramic powder content is 3 - 8 vol%, and the ceramic and copper compound matrix content formed by infiltration is 10 - 35 vol%.

[0013] The ultra-high temperature ceramic powder described in step (1) is one or more of HfC, ZrC, TaC, TiC, and NbC.

[0014] The density range of the ultra-high temperature ceramic powder modified carbon fiber preform described in step (1) is 0.75 - 1.20 g / cm 3 .

[0015] The pyrolytic carbon chemical vapor densification treatment described in step (2) has a densification time of 90 - 180 h.

[0016] The ultra-high temperature ceramic modified C / C porous body described in step (2) has a density range of 1.30 - 1.65 g / cm 3 .

[0017] The infiltration powder described in step (3) is a mixed powder of Cu5Si and ZrSi2, wherein the content of Cu5Si is 10 - 20 wt%.

[0018] The infiltration powder described in step (3) is a mixed powder of Cu5Si and ZrSi2. To ensure the uniformity of the mixed powder, ball milling is used for mixing. The ball milling speed is 120 - 300 r / min, and the ball milling mixing time is ≥ 8 h.

[0019] The low-vacuum reactive infiltration process described in step (3) is as follows: evacuate to < 0.1 kPa, maintain a vacuum degree of < 0.1 kPa under the evacuation condition, and then heat up at a rate of 6 - 7 °C / min; after heating up to 1450 °C; under a vacuum condition of < 0.1 kPa, perform heat preservation infiltration at 1450 °C, and the infiltration time is 20 - 60 min.

[0020] The argon filling and pressurization described in step (4), the temperature should be maintained at 1450 °C during pressurization, and the pressure after argon filling is 3 - 10 MPa.

[0021] The pressure infiltration temperature point for heating up to a higher temperature described in step (4): during the heating process, the heating rate is 6 - 7 °C / min; for the pressure infiltration temperature point at a higher temperature, the pressure infiltration temperature is required to be 1800 - 2100 °C.

[0022] The high-temperature and high-pressure reactive infiltration process described in step (4) is as follows: after heating up to 1800 - 2100 °C, keep it warm, and perform pressure-holding infiltration under the temperature and pressure conditions of 3 - 10 MPa and 1800 - 2100 °C, and the pressure-holding infiltration time is 30 - 90 min.

[0023] The natural cooling and temperature reduction for sampling described in step (4), during the temperature reduction process, the pressurized state should be maintained. When the furnace temperature drops to < 300 °C, start to release pressure and open the furnace for sampling.

[0024] The present invention has the following advantages:

[0025] (1) To further improve the high-temperature ablation resistance of the ultra-high temperature ceramic modified C / C composite material, combining the excellent ablation resistance of the ultra-high temperature ceramic and the advantage of the sweating cooling of copper compounds. Since the ultra-high temperature ceramic matrix in the composite material prepared by the present invention is mainly composed of ceramic powder and ceramic phases formed by infiltration reaction, the content of the ultra-high temperature ceramic phase in it is further increased compared with the content of the ultra-high temperature ceramic phase in the material prepared by a single infiltration reaction process. At the same time, the sweating cooling of copper compounds can effectively reduce the temperature of the ablation surface, which is beneficial to enhancing the high-temperature ablation resistance of the material.

[0026] (2) By utilizing the high and low viscosities and infiltration characteristics of different melts, and by designing the proportion of low-viscosity Cu5Si and high-viscosity ZrSi2 melts in the infiltration material (the content of Cu5Si is 10-20 wt%), a two-step infiltration process of low-vacuum reactive infiltration and ultra-high temperature pressure reactive infiltration is presented, which solves the problem of uniform infiltration of melts with different viscosities during the infiltration process. First, at the low-temperature stage, the low-viscosity Cu5Si melt is infiltrated into the material by using the low-vacuum reactive infiltration process to achieve rapid infiltration of the low-viscosity melt; secondly, by raising the temperature, the viscosity of the high-viscosity ZrSi2 melt is appropriately reduced, and the pressure infiltration process is used to enhance the infiltration effect of the high-viscosity melt, thereby increasing the material density and reducing its open porosity.

[0027] (3) The rapid preparation method of ultra-high temperature ceramics and copper compound modified C / C composites proposed by the present invention is more suitable for industrial production. This method has the advantages of simple equipment process, short time, low cost, and high ceramic content. Since the material prepared by the two-step infiltration process of low-vacuum reactive infiltration and ultra-high temperature pressure reactive infiltration has the characteristics of high density and low open porosity, it is beneficial to improve the high-temperature ablation resistance and erosion resistance of the material. Description of the Drawings

[0028] Figure 1 It is the phase analysis result of the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1;

[0029] Figure 2 It is the optical microstructure photograph of the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1;

[0030] Figure 3 It is the micro-morphology diagram of the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1;

[0031] Figure 4 It is the micro-magnified morphology diagram and energy spectrum analysis result of the ceramic matrix in the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1;

[0032] Figure 5 It is the physical photograph of the two materials after oxyacetylene ablation prepared in Example 1;

[0033] Figure 6 It is the temperature curve of the specimen surface during the ablation process of the two materials prepared in Example 1;

[0034] Figure 7 It is the phase analysis result of the surface oxide film of the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1 after ablation;

[0035] Figure 8 Microscopic morphology and energy spectrum analysis results of the oxide film at the ablation center of the ultra-high temperature ceramic and copper compound modified C / C composite prepared in Example 1. Specific implementation mode

[0036] Example 1: Using carbon fiber mesh tire, non-woven fabric and HfC ceramic powder as raw materials, an ultra-high temperature ceramic powder modified carbon fiber preform was prepared by the method of mixing ceramic powder and carbon fiber. The specific process is as follows: A layer of non-woven fabric and a layer of mesh tire sandwich the ultra-high temperature ceramic powder. When laying the layers, the HfC powder is evenly spread on the pores of the carbon fiber mesh tire. Then, the preform is alternately laminated in the order of non-woven fabric / carbon fiber mesh tire + HfC ceramic powder / non-woven fabric / carbon fiber mesh tire + HfC ceramic powder. The non-woven fabric is laid in a 0° / 90° / 0° pattern. Finally, the mesh tire layer and non-woven fabric layer containing HfC powder are connected into a whole by continuous needling, and a HfC powder modified carbon fiber preform with a density of 0.93 g / cm 3 was prepared. The prepared HfC powder modified carbon fiber preform was placed in a chemical vapor deposition furnace for pyrolytic carbon deposition densification. During the deposition process, the deposition pressure ≤ 0.3 kPa, and the deposition temperature was 980 - 1050 °C. After 120 h of deposition, a HfC ceramic powder modified C / C porous body with a density of 1.5 g / cm 3 was prepared.

[0037] The prepared HfC ceramic powder-modified C / C porous body was machined, ultrasonically cleaned, and dried for later use. Cu5Si and ZrSi2 were ball-milled and mixed at a mass ratio of 1:9. The rotation speed during ball milling was 200 r / min, and the ball milling mixing time was 8 h. The uniformly mixed infiltration powder and the dried HfC ceramic powder-modified C / C porous body were placed together in a graphite crucible, and when placing, ensure that the C / C porous body was buried in the mixed powder. Subsequently, the graphite crucible containing the porous body and the infiltration powder was placed in a pressure infiltration furnace for the first-stage low-vacuum reactive infiltration. The specific process was as follows: evacuate to 90 Pa, maintain a vacuum degree of <0.1 kPa under the vacuum condition, and then heat up at a rate of 6 - 7 °C / min; after heating up to 1450 °C; under a vacuum condition of 90 Pa, perform heat preservation infiltration at 1450 °C, and the infiltration time was 30 min. After the low-vacuum reactive infiltration process ended, argon was filled for pressurization. The temperature should be maintained at 1450 °C during pressurization, and the pressure after filling argon was 3 - 10 MPa. Subsequently, heat up to the pressure infiltration temperature point at a higher temperature for the second-stage high-temperature and high-pressure reactive infiltration. During the heating process, the heating rate was 6 - 7 °C / min; after heating up to 1800 °C, perform heat preservation, and perform pressure holding infiltration under the temperature and pressure conditions of 3 - 10 MPa and 1800 °C, and the pressure holding infiltration time was 30 min. After the second-stage ultra-high-temperature pressure reactive infiltration process ended, it was naturally cooled. During the cooling process, the pressurized state was maintained. When the furnace temperature dropped to <300 °C, start to release pressure and open the furnace for sampling. The final density of the ultra-high-temperature ceramic and copper compound-modified C / C composite material prepared by the low-vacuum and ultra-high-temperature pressure reactive infiltration process was 3.05 g / cm 3 , and the open porosity was 7.71%. As a comparative material, the C / C-HfC-SiC composite material in the early stage adopted the same powder weaving and chemical vapor deposition process. After the density of the HfC ceramic powder-modified C / C porous body reached 1.5 g / cm 3 , the SiC densification treatment was carried out by the precursor infiltration-pyrolysis process. After 16 times of infiltration and pyrolysis, the final density of the prepared C / C-HfC-SiC composite material was 1.94 g / cm 3 .

[0038] Figure 1 Figure 10 shows the phase analysis results of the ultra-high-temperature ceramic and copper compound-modified C / C composite material prepared in Example 1. It can be seen from the XRD pattern that the main phases of the material are carbides such as HfC, ZrC, SiC, ZrSi2, C, copper compounds such as CuZr and Cu4Si6Zr, etc.

[0039] Figure 2 Figure 11 is the optical microstructure photograph of the ultra-high-temperature ceramic and copper compound-modified C / C composite material prepared in Example 1. From Figure 2It can be seen that a large amount of ceramics and copper compounds are filled in the pores of the preform, and different phases exhibit different contrast characteristics.

[0040] Figure 3 It is the micrograph of the ultra-high temperature ceramic and copper compound modified C / C composite prepared in Example 1. Figure 3 As can be seen from a, there are four phases with different contrasts in the figure. According to the XRD pattern, the black phase is mainly carbon fiber and pyrolytic carbon, the white and bright phase is HfC, the gray and white phase is ZrC and copper compounds, and the gray and black phase is mainly SiC and Si. Figure 3 As can be seen from b, the white and bright phase HfC is mainly filled in the voids around the fibers, and a layer of pyrolytic carbon wraps around the carbon fibers. Figure 3 c is the enlarged micrograph of the white and bright phase. It can be seen that HfC is in the form of particle accumulation and there are certain micropores, which are mainly related to the weaving introduction method. Figure 3 d is the micrograph of the ceramic phase formed at the fiber micropores. It can be found that there are a large number of white and bright HfC particles and massive ceramic phases formed by reaction at the micropores around the fibers.

[0041] Figure 4 In Figure 4 a is the enlarged micrograph of the ceramic matrix in the ultra-high temperature ceramic and copper compound modified C / C composite prepared in Example 1, and 4b - 4e are the energy spectrum analysis results. It can be found that the Si content of the gray and black phase at A is relatively high ( Figure 4 b), which is mainly composed of SiC and Si. While at the gray and white phases B and D ( Figure 4 c and 4e), the energy spectrum analysis results show that the contents of Zr, C and Cu elements are relatively high, and it is mainly composed of ZrC and copper-zirconium compounds; in the C region, the contents of Si, C and Cu elements are relatively high, indicating that the gray and black phase also contains SiC and silicon-copper compounds.

[0042] Table 1 shows the mechanical and thermophysical property test results of the ultra-high temperature ceramic and copper compound modified C / C composite prepared in Example 1. The mechanical property test results in Table 1 show that the average flexural and compressive strength values of the prepared ultra-high temperature ceramic and copper compound modified C / C composite are 136.17 and 190.76 MPa respectively, the room temperature thermal conductivity is 19.45 W / (mK), and the linear expansion coefficient from room temperature to 1000 °C is in the range of 1.36 - 3.52×10 -6 / °C.

[0043] Table 1

[0044]

[0045] Table 2 shows the test results of the oxy-acetylene flame high-temperature ablation resistance performance of the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1. As can be seen from Table 2, compared with the C / C-HfC-SiC composites prepared by powder mixing and precursor impregnation pyrolysis, the high-temperature ablation resistance performance of the composites prepared by the two-step infiltration process is significantly improved. At a heat flux density of 3.2 MW / m 2 , after 30 s of oxy-acetylene ablation, the linear ablation rate and mass ablation rate of the ultra-high temperature ceramics and copper compound modified C / C composites are 3.0 μm / s and 0 mg / s respectively, while after ablation under the same conditions, the linear ablation rate and mass ablation rate of the C / C-HfC-SiC composites are 17.3 μm / s and 7.1 mg / s respectively, indicating that the ultra-high temperature ceramics and copper compound modified C / C composites prepared by the low-vacuum and ultra-high temperature pressure reaction infiltration process have excellent high-temperature ablation resistance performance.

[0046] Table 2

[0047]

[0048] Figure 5 are the physical photos of the two materials prepared in Example 1 after oxy-acetylene ablation. It can be seen that after ablation of the C / C-HfC-SiC composites, although a white oxide protective film is formed on the ablation surface, partial peeling occurs in the ablation center film, while after ablation of the ultra-high temperature ceramics and copper compound modified C / C composites, a continuous and dense oxide protective film covers the ablation center, thus playing a better ablation protection effect.

[0049] Figure 6 are the temperature curves of the specimen surfaces during the ablation process of the two materials prepared in Example 1. It can be seen that during the entire ablation process, due to the sweating and cooling effect of the copper compound, the temperature of the ablation surface of the ultra-high temperature ceramics and copper compound modified C / C composites is reduced by more than 200 °C compared with the surface temperature of the C / C composites. When the ablation ends, the maximum ablation temperatures of the two materials' surfaces reach 2261.97 and 2545.59 °C respectively. In contrast, the introduction of the copper compound reduces the maximum ablation temperature by 283 °C, further confirming that the copper compound has a good sweating and cooling effect and effectively improves the high-temperature ablation resistance performance of the material.

[0050] Figure 7 are the phase analysis results of the surface oxide film of the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1 after ablation. It can be seen that after ablation of the high-temperature ceramics and copper compound modified C / C composites, the oxide film on the material surface is mainly composed of HfO2, ZrO2, SiO2, CuO, and Cu2O, and its oxide composition is basically consistent with the matrix oxidation product composition.

[0051] Figure 8 Microscopic morphology and energy spectrum analysis results of the oxide film at the ablation center of the ultra-high temperature ceramics and copper compound modified C / C composites prepared in Example 1. As can be seen from Figure 8 a, after ablation, a continuous and dense oxide protective film is formed on the material surface, which plays a good role in oxygen resistance and heat insulation, thus enabling the material to have excellent high-temperature ablation resistance. In addition, as can also be seen from Figure 8 a, the oxidation products in the oxide film show different contrast characteristics. The microscopic magnified morphology diagram shows ( Figure 8 b) that the smooth and dense grayish-white massive phase mainly contains C, O, Si, Zr, Hf, Cu, among which the contents of Zr and O elements are the highest ( Figure 8 e), indicating that it is mainly composed of ZrO2. In addition, there are also granular white bright phases on the surface of the oxide film ( Figure 8 c), whose size is significantly smaller than that of the grayish-white phase, and the degree of grain melting is significantly weaker. The energy spectrum analysis results confirm ( Figure 8 f) that this white bright phase is also composed of C, O, Si, Zr, Hf, Cu, but the contents of Hf and O elements are the highest, indicating that it is mainly composed of HfO2. At the same time, a small amount of SiO2 glass area is also found in the local area of the oxide film. Its structure is relatively smooth and dense, mainly showing grayish-black, indicating that after ablation, the remaining SiO2 glass phase in the oxide film is less.

[0052] Example 2: Using carbon fiber mesh tire, non-woven fabric and NbC ceramic powder as raw materials, an ultra-high temperature ceramic powder modified carbon fiber preform was prepared by the technology of mixing ceramic powder and carbon fiber. The specific process is as follows: One layer of carbon fiber cloth and one layer of mesh tire are used to sandwich the ultra-high temperature ceramic powder. When laying the layers, the NbC powder is evenly spread on the pores of the carbon fiber mesh tire, and then the preform is alternately laminated in the order of non-woven fabric / carbon fiber mesh tire + NbC ceramic powder / non-woven fabric / carbon fiber mesh tire + NbC ceramic powder. The non-woven fabric is laid in a 0° / 90° / 0° pattern. Finally, the mesh tire layer and non-woven fabric layer containing NbC powder are connected into a whole by continuous needling to prepare a NbC powder modified carbon fiber preform with a density of 0.90 g / cm 3 The prepared NbC powder modified carbon fiber preform was put into a chemical vapor deposition furnace for pyrolytic carbon deposition densification. During the deposition process, the deposition pressure ≤ 0.3 kPa, the deposition temperature is 980 - 1050 °C. After 130 h of deposition, a NbC ceramic powder modified C / C porous body with a density of 1.55 g / cm 3 was prepared.

[0053] The prepared NbC ceramic powder-modified C / C porous body is machined, ultrasonically cleaned and dried for later use. Cu5Si and ZrSi2 are ball-milled and mixed at a mass ratio of 2:8. The rotation speed during ball milling is 250 r / min, and the ball milling mixing time is 10 h. The uniformly mixed infiltration powder and the dried NbC ceramic powder-modified C / C porous body are placed together in a graphite crucible, and when placing, ensure that the C / C porous body is buried in the mixed powder. Subsequently, the graphite crucible containing the porous body and the infiltration powder is placed in a pressure infiltration furnace for the first-stage low-vacuum reactive infiltration. The specific process is as follows: evacuate to 90 Pa, maintain a vacuum degree of <0.1 kPa under the vacuum condition, and then heat up at a rate of 6-7 °C / min; after heating up to 1450 °C; under the vacuum condition of 90 Pa, perform heat preservation infiltration at 1450 °C, and the infiltration time is 30 min. After the low-vacuum reactive infiltration process ends, argon is filled for pressurization. The temperature should be maintained at 1450 °C during pressurization, and the pressure after filling argon is 4-10 MPa. Subsequently, heat up to the pressure infiltration temperature point at a higher temperature for the second-stage high-temperature and high-pressure reactive infiltration. During the heating process, the heating rate is 6-7 °C / min; after heating up to 1800 °C, perform heat preservation, and perform pressure-holding infiltration under the temperature and pressure conditions of 4-10 MPa and 1800 °C, and the pressure-holding infiltration time is 45 min. After the second-stage ultra-high-temperature pressure reactive infiltration process ends, it is cooled naturally. During the cooling process, the pressurized state should be maintained. When the furnace temperature drops to <300 °C, start to release pressure and open the furnace to take samples. The final density of the ultra-high-temperature ceramic and copper compound-modified C / C composite material prepared by the low-vacuum and ultra-high-temperature pressure reactive infiltration process is 2.89 g / cm 3 , and the open porosity is 7.73%.

[0054] Example 3: Using carbon fiber mesh tire, satin cloth and a ZrC and TaC mixed powder as raw materials, the mixed powder is ball-milled and mixed evenly at a mass ratio of ZrC:TaC of 1:1. Subsequently, an ultra-high-temperature ceramic powder-modified carbon fiber preform is prepared by the ceramic powder and carbon fiber co-weaving technology. The specific process is as follows: sandwich an ultra-high-temperature ceramic powder with one layer of satin cloth and one layer of mesh tire. When laying the layers, evenly spread the ZrC-TaC mixed powder at the pores of the carbon fiber mesh tire. Subsequently, alternately stack and lay the preform in the order of satin cloth / carbon fiber mesh tire + ZrC-TaC mixed powder / satin cloth / carbon fiber mesh tire + ZrC-TaC mixed powder. Finally, connect the mesh tire layer and the satin cloth layer containing the mixed powder into a whole by means of piercing, and a preform with a density of 1.15 g / cm 3ZrC-TaC powder modified carbon fiber preform. The prepared ZrC-TaC powder modified carbon fiber preform was placed in a chemical vapor deposition furnace for pyrolytic carbon deposition densification. During the deposition process, the deposition pressure ≤ 0.3 kPa, and the deposition temperature was 980 - 1050 °C. After 95 h of deposition, a density of 1.65 g / cm 3 ZrC-TaC ceramic powder modified C / C porous body.

[0055] The prepared ZrC-TaC ceramic powder modified C / C porous body was machined, ultrasonically cleaned and dried for standby. Cu5Si and ZrSi2 were ball-milled and mixed at a mass ratio of 1:9. The rotation speed during ball milling was 250 r / min, and the ball milling mixing time was 10 h. The uniformly mixed infiltration powder and the dried ZrC-TaC ceramic powder modified C / C porous body were placed together in a graphite crucible, and during placement, the C / C porous body was ensured to be buried in the mixed powder. Subsequently, the graphite crucible containing the porous body and the infiltration powder was placed in a pressure infiltration furnace for the first-stage low-vacuum reactive infiltration. The specific process was as follows: evacuated to 90 Pa, maintained a vacuum degree of < 0.1 kPa under the vacuum condition, and then heated at a rate of 6 - 7 °C / min; after heating to 1450 °C; under the vacuum condition of 90 Pa, carried out holding infiltration at 1450 °C, and the infiltration time was 30 min. After the low-vacuum reactive infiltration process ended, argon was filled for pressurization, and the temperature should be maintained at 1450 °C during pressurization, and the pressure after filling argon was 3 - 6 MPa. Subsequently, it was heated to the pressure infiltration temperature point at a higher temperature for the second-stage high-temperature and high-pressure reactive infiltration. During the heating process, the heating rate was 6 - 7 °C / min; after heating to 2000 °C, holding was carried out, and pressure holding infiltration was carried out under the temperature and pressure conditions of 3 - 6 MPa and 2000 °C, and the pressure holding infiltration time was 60 min. After the second-stage ultra-high-temperature pressure reactive infiltration process ended, it was naturally cooled. During the cooling process, the pressurized state should be maintained. When the furnace temperature dropped to < 300 °C, the pressure was released and the furnace was opened for sampling. The final density of the ultra-high-temperature ceramic and copper compound modified C / C composite material prepared by the low-vacuum and ultra-high-temperature pressure reactive infiltration process was 3.45 g / cm 3 , and the open porosity was 6.57%.

Claims

1. A rapid preparation method of ultra-high temperature ceramics and copper compound modified C / C composites, characterized in that, The composite material described above is composed of ultra-high temperature ceramics, cuprates, pyrolytic carbon, and carbon fiber reinforcements; the rapid preparation method includes the following steps: (1) Preparation of ultra-high temperature ceramic powder modified carbon fiber preform: Using ultra-high temperature ceramic powder and carbon fiber as raw materials, an ultra-high temperature ceramic powder modified carbon fiber preform is prepared by the method of mixing powder and carbon fiber preform; the specific process is as follows: One layer of carbon fiber cloth and one layer of web are used to sandwich ultra-high temperature ceramic powder, and the fiber web and carbon fiber cloth are alternately stacked in sequence. During the stacking process, the ultra-high temperature ceramic powder is evenly dispersed in each layer of the web. Then, needling or piercing is used to connect the web layer containing ceramic powder and the fiber cloth into a whole. After introducing carbon fiber in the thickness direction, an ultra-high temperature ceramic powder modified carbon fiber preform is obtained; (2) Pyrolytic carbon matrix densification: The ultra-high temperature ceramic powder modified carbon fiber preform prepared in (1) is put into a chemical vapor deposition furnace for pyrolytic carbon chemical vapor densification treatment to obtain an ultra-high temperature ceramic modified C / C porous body; (3) Low-vacuum reactive infiltration: The ultra-high temperature ceramic modified C / C porous body prepared in (2) is machined, ultrasonically cleaned and dried, then the above porous body is placed in infiltration powder and put together into a graphite crucible. Subsequently, the graphite crucible containing the porous body and infiltration powder is put into a pressure infiltration furnace, heated to a predetermined temperature and then low-vacuum reactive infiltration is carried out; the infiltration powder is a mixed powder of Cu5Si and ZrSi2, and the content of Cu5Si is 10 - 20 wt%; the low-vacuum reactive infiltration process is: evacuate to <0.1 kPa and maintain a vacuum degree of <0.1 kPa under the evacuation condition; after heating to 1450 °C, under the vacuum condition of <0.1 kPa, keep warm and infiltrate at 1450 °C, and the infiltration time is 20 - 60 min; (4) Ultra-high temperature pressure reactive infiltration: After the low-vacuum reactive infiltration process in (3) ends, argon is filled for pressurization, and the temperature is kept at 1450 °C during pressurization, and the pressure after filling argon is 3 - 10 MPa; Subsequently, it is heated to the pressure infiltration temperature point of 1800 - 2100 °C for the high-temperature and high-pressure reaction infiltration in the second stage. After the holding time of pressure infiltration for 30 - 90 min, it is naturally cooled. During the cooling process, the pressurized state is maintained. When the furnace temperature drops to <300 °C, the pressure is released and the furnace is opened; the density of the ultra-high temperature ceramic and copper compound modified C / C composite obtained is 2.85 - 3.7 g / cm 3 ; by volume percentage, it includes the following components: the carbon fiber content is 15 - 45 vol%, the pyrolytic carbon content is 15 - 35 vol%, the ultra-high temperature ceramic powder content is 3 - 8 vol%, and the ceramic and copper compound matrix content formed by infiltration is 10 - 35 vol%.

2. The rapid preparation method of an ultra-high temperature ceramic and a copper compound modified C / C composite material according to claim 1, characterized in that: (1) The ultra-high temperature ceramic powder described above is one or more of HfC, ZrC, TaC, TiC, and NbC.

3. A rapid preparation method of an ultra-high temperature ceramic and a copper compound modified C / C composite material according to claim 1, characterized in that: (1) The density range of the ultra-high temperature ceramic powder modified carbon fiber preform described in is 0.75 - 1.20 g / cm 3 .

4. A rapid preparation method of an ultra-high temperature ceramic and a copper compound modified C / C composite material according to claim 1, characterized in that: (2) In the pyrolytic carbon chemical vapor densification treatment described above, the densification time is 90 - 180 h.

5. A rapid preparation method of an ultra-high temperature ceramic and a copper compound modified C / C composite according to claim 1, characterized in that: (2) The density range of the ultra-high temperature ceramic modified C / C porous body described is 1.30 - 1.65 g / cm 3 .

6. A rapid preparation method of an ultra-high temperature ceramic and a copper compound modified C / C composite material according to claim 1, characterized in that: (3) The mixed powder of Cu5Si and ZrSi2 described above is mixed by ball milling, the ball milling speed is 120 - 300 r / min, and the ball milling mixing time ≥8 h.

7. A rapid preparation method of an ultra-high temperature ceramic and a copper compound modified C / C composite according to claim 1, characterized in that: (4) In the heating described above, the heating rate is 6 - 7 °C / min.

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