A C / SiC-ZrB2-HfB2-Cu composite material and its preparation method

Abstract

The present application relates to the technical fields of ceramic matrix composite material preparation, and particularly relates to a C / SiC-ZrB2-HfB2-Cu composite material and a preparation method thereof. The method comprises the following steps: (1) preparing a C-ZrB2-HfB2 mixed slurry; (2) placing a carbon fiber preform with a pyrolytic carbon interface layer into the mixed slurry, and performing vacuum centrifugal impregnation treatment, and then taking out and drying to obtain a blank; (3) placing the blank into a crucible, and embedding with silicon-copper alloy to obtain the C / SiC-ZrB2-HfB2-Cu composite material. The present application utilizes the dual driving effects of vacuum and centrifugal force to ensure that the slurry fully and uniformly penetrates into the blank. Compared with the traditional C / SiC-Cu or C / SiC-ZrC-Cu composite material, the ceramic components are more uniformly distributed in the material, the temperature resistance of the material is stronger, the linear ablation rate is lower, the mechanical properties of the material are stronger, and the bending strength can reach more than 250 MPa.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composite material preparation technology, specifically to a C / SiC-ZrB2-HfB2-Cu composite material and its preparation method. Background Technology

[0002] Scramjet engines are the core power source for high-speed aircraft above Mach 5. Key components such as the engine combustion chamber must operate in a combustion gas environment exceeding 2000°C, while simultaneously withstanding the mechanical impact of condensed particles and the chemical corrosion of an oxidizing atmosphere. The engine's operating environment is one of the harshest and most demanding thermal environments among all aerospace propulsion systems. Its thermal protection system directly determines whether the engine can operate stably and cruise for extended periods, placing extremely stringent requirements on thermal protection materials. Ceramic matrix composites, multiphase composites with ceramic as the matrix and continuous fiber reinforcement, retain the advantages of ceramics such as high temperature resistance, corrosion resistance, and low density. Simultaneously, fiber toughening overcomes the fatal flaws of traditional ceramics—high brittleness and easy fracture—making it a core material to replace high-temperature alloys and traditional ceramics under extreme operating conditions.

[0003] Currently, representative ceramic matrix composites mainly include C / SiC (service environment generally not exceeding 1650℃), C / SiC-ZrC or ZrB2 (service environment generally not exceeding 2300℃), C / SiC-HfC or HfB2 (service environment generally not exceeding 2500℃), and their related modified composites. Among these, while the C / SiC-HfC series materials can meet the 2500℃ operating environment of scramjet engine thermal protection systems, their manufacturing cost is extremely high. Patent CN202310008951.2 proposes a method for preparing C / SiC-ZrC-Cu3Si composite materials. Although this method solves the problems of low cost and short cycle time, its performance still falls short of the requirements for use in extreme environments. Therefore, developing a low-cost, short-cycle, heat-resistant composite material that can withstand temperatures above 2500℃ and has an ultra-long service life is a key problem urgently needing to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a C / SiC-ZrB2-HfB2-Cu composite material and its preparation method. The composite material prepared by this method has thermal conductivity, can achieve near-zero ablation characteristics under high heat flux and long-term conditions, and the process is simple and easy to promote.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a C / SiC-ZrB2-HfB2-Cu composite material includes the following steps: (1) Prepare C-ZrB2-HfB2 mixed slurry; (2) The carbon fiber preform with the pyrolytic carbon interface layer is placed in the mixed slurry prepared in step (1), vacuum centrifuged and impregnated, then removed and dried to obtain C f / C-ZrB2-HfB2 blank; (3) Take C from step (2) f The C / SiC-ZrB2-HfB2 blank was placed in a crucible and embedded with a silicon-copper alloy to obtain the C / SiC-ZrB2-HfB2-Cu composite material.

[0006] Further, in step (1), the preparation process of the C-ZrB2-HfB2 mixed slurry is specifically as follows: mixing carbon aerogel powder, ZrB2 powder, HfB2 powder, water and dispersant and ball milling.

[0007] The specific surface area of ​​the carbon aerogel powder is 100~300 m². 2 / g (preferably 150~250mg) 2 / g), with a particle size of 500~800nm, ZrB2 powder with a particle size of 300~500nm (preferably 300~400nm), and HfB2 powder with a particle size of 100~300nm (preferably 200~300nm). The dispersant is one or more of sodium tripolyphosphate, sodium polyacrylate, polyvinyl alcohol, polystyrene, and polyethyleneimine; The mass ratio of the carbon aerogel powder, ZrB2 powder, HfB2 powder, water, and dispersant is 1:(4~6):(1~2):(100~200):(0.1~0.5). The ball milling media is zirconium oxide, the ball diameter is 4~10mm (preferably 7~10mm), the ball-to-material volume ratio is 4:1, the ball milling speed is 300~700 rpm (preferably 500~700 rpm), and the ball milling time is 5~12h (preferably 8~10h).

[0008] Furthermore, in step (2), the carbon fiber preform adopts a fine-woven puncture structure, with a fiber volume content of 30-40% (preferably 30-35%) and a density of 0.55-0.75 g / cm³. 3 (Preferred concentration: 0.60~0.65 g / cm³) 3 ); The pyrolytic carbon interface layer has a thickness of 2-5 μm; it is prepared using a chemical vapor infiltration process, with one or both of Ar and N2 as carrier and dilution gases, and one or both of natural gas and C3H8 as gaseous precursors, with a precursor concentration of 10%-50%; the deposition temperature is 900-1000℃, and the deposition time is 30-100 h; the density of the carbon fiber preform with the pyrolytic carbon interface layer is 0.8-1.2 g / cm³.3 The C f The density of the / C-ZrB2-HfB2 blank is 1.5~2.0 g / cm³. 3 .

[0009] Furthermore, in step (2), the process parameters for vacuum centrifugal impregnation are: vacuum degree ≤100Pa; rotation speed 300~500r / min; impregnation time 10~30h; The drying temperature is 150℃, and the drying time is 5~7 hours.

[0010] Further, in step (3), the particle size of the silicon-copper alloy is 0.3~0.5μm, the silicon-copper atomic ratio in the silicon-copper alloy is (2~6):1; the embedding temperature is 1100~1400℃ (preferably 1200~1350℃), and the embedding time is 1~3h.

[0011] A C / SiC-ZrB2-HfB2-Cu composite material prepared according to the above preparation method.

[0012] The density of this composite material is ≥2.8 g / cm³. 3 The Cu conductive agent forms a three-dimensional continuous network structure in the matrix, and the ZrB2-HfB2 particles are uniformly dispersed in the SiC matrix. During service, the surface temperature is 300~700℃ lower than that of traditional ceramic matrix composites.

[0013] Meanwhile, C / SiC-UHTC (ZrC / ZrB2-HfB2 / HfC)-Cu composite materials with different ultra-high temperature ceramic matrix systems can also be prepared according to the method of the present invention.

[0014] Compared with the prior art, the present invention has the following significant advantages: (1) The present invention utilizes the dual driving effect of vacuum and centrifugal force to ensure that the slurry is fully and uniformly penetrated in the blank, providing a foundation for subsequent ceramic metallization and performance improvement.

[0015] (2) The Cu conductive agent forms a three-dimensional continuous network structure in the matrix, and the ZrB2-HfB2 particles are uniformly dispersed in the SiC matrix. In the ceramic metallization reaction, the Cu conductive agent precipitated in situ in the silicon-copper alloy can form a highly efficient heat conduction channel during ultra-high temperature service. On the one hand, the conductive agent rapidly conducts outward in the form of sweating under high surface heat flux, significantly reducing the surface temperature; on the other hand, SiC-ZrB2-HfB2 ultra-high temperature ceramics have excellent ablation resistance properties. The two work together to achieve a significant improvement in long-term ultra-high temperature heat protection performance, namely ablation resistance and low surface temperature.

[0016] (3) Compared with the traditional melting and infiltration process, the ceramic metallization temperature of this process is lower.

[0017] (4) Compared with traditional C / SiC-Cu or C / SiC-ZrC-Cu composite materials, the ceramic components are more uniformly distributed inside the material, the material has stronger temperature resistance, can be used in environments above 2500℃, and has a lower linear ablation rate; the material has stronger mechanical properties, and the bending strength can reach more than 250MPa.

[0018] (5) Compared with traditional C / SiC-UHTC (ZrB2, HfC or HfB2) composite materials, the material density is lower and the material preparation cost is lower, only 1 / (2~5). Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the preparation method of the present invention; Figure 2 This is a schematic diagram of the working principle of a vacuum centrifugal impregnation device, where 1 represents the vacuum valve, 2 represents the tank cover, 3 represents the tank, 4 represents the fixed baffle, 5 represents the carbon fiber preform, 6 represents the filter baffle, 7 represents the drive wheel, 8 represents the transmission belt, 9 represents the drive motor, 10 represents the material chamber, and 11 represents the waste liquid chamber. Figure 3 Photographs of ablation samples of the materials obtained in the examples and comparative examples; Figure 4 The image shows a scanning electron microscope (SEM) image of the C / SiC-ZrB2-HfB2-Cu composite material prepared in Example 1; wherein, Figure 4 (a) is the interface layer structure. Figure 4 (b) is the matrix structure; Figure 5 The image shows a scanning electron microscope (SEM) image of the tensile fracture surface of the C / SiC-ZrB2-HfB2-Cu composite material prepared in Example 1. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] Example 1 The preparation process of this invention is as follows: Figure 1 As shown. Specifically: Carbon aerogel powder (specific surface area 150m²) 2A mixture of ZrB2 powder (particle size 500-800 nm), HfB2 powder (particle size 300-400 nm), water, and polyvinyl alcohol in a mass ratio of 1:6:2:150:0.5 was placed in a ball mill jar with 7 mm diameter zirconia balls at a ball-to-particle ratio of 4:1. The mixture was milled at 700 rpm for 10 hours to obtain a C-ZrB2-HfB2 slurry.

[0022] Then, vacuum centrifugal impregnation is performed. The working principle of the vacuum centrifugal impregnation device is as follows: Figure 2 As shown. The vacuum centrifugal impregnation device comprises two parts: a tank assembly and a drive unit. The tank assembly consists of a material chamber 10, a waste liquid chamber 11, a vacuum valve 1, a tank cover 2, a tank body 3, a fixed baffle 4, a filter baffle 6, and a drive wheel 7. The drive unit consists of a drive motor 9 and a transmission belt 8. The tank cover 2 and the tank body 3 are bolted together, and the fixed baffle 4 and the filter baffle 6 are bolted together. First, a sample with dimensions of 100mm × 100mm × 10mm, a fiber volume content of 32%, and a density of 0.55g / cm³ is prepared. 3 (Carbon fiber preform), a finely braided puncture structure, and a pyrolytic carbon interface layer thickness of 2μm (the fiber preform was purchased from Jiangsu Tianniao High-Tech Co., Ltd.; the pyrolytic carbon interface layer was prepared on the fiber surface by chemical vapor infiltration, wherein Ar was used as the carrier gas and dilution gas, C3H8 was used as the gas phase precursor, and the gas concentration was 15%; the deposition temperature was 1000℃, the deposition time was 30h, and the density of the final carbon fiber preform with a pyrolytic carbon interface layer thickness of 2μm was 1.0g / cm³). 3 The mixture is placed on the filter baffle 6, and the fixing baffle 4 is fixed with bolts. Then, the mixed slurry is poured into the material chamber 10, with the liquid level flush with the chamber body, at which point the liquid level completely submerges the carbon fiber preform. Finally, the tank cover 2 is placed on top, and the cover 2 is fixed to the tank body 3 with bolts. The vacuum valve 1 is opened, and the vacuum is evacuated to below 100 Pa. After the vacuum reaches the target value, the drive motor 9 is started for centrifugal impregnation at 300 r / min for 30 hours, ensuring that the liquid level of the mixed slurry always submerges the carbon fiber preform during the impregnation process. After removal, it is dried at 150℃ for 5 hours to obtain C f / C-ZrB2-HfB2 blank (density 1.50 g / cm³) 3 ).

[0023] The blank was placed in a graphite crucible and completely covered with silicon-copper alloy powder (particle size 0.3~0.5μm) at a silicon-copper atomic ratio of 4:1. The temperature was raised to 1350℃ and held for 2 hours for ceramic metallization treatment. The final product had a density of 3.0 g / cm³. 3 C / SiC-ZrB2-HfB2-Cu composite material test block.

[0024] Example 2 Carbon aerogel powder (specific surface area 150m²) 2 A mixture of ZrB2 powder (particle size 500-800 nm), HfB2 powder (particle size 300-400 nm), water, and polyvinyl alcohol in a mass ratio of 1:6:1:150:0.5 was placed in a ball mill jar with 7 mm diameter zirconia balls at a ball-to-particle ratio of 4:1. The mixture was milled at 700 rpm for 10 hours to obtain a C-ZrB2-HfB2 slurry.

[0025] Then, vacuum centrifugation impregnation was performed, following the same steps as in Example 1. After impregnation, the sample was removed and dried at 150°C for 5 hours to obtain C. f / C-ZrB2-HfB2 blank (density 1.45g / cm³) 3 ).

[0026] The blank was placed in a graphite crucible and completely covered with silicon-copper alloy powder (particle size 0.3~0.5μm), with a silicon-copper atomic ratio of 4:1. The temperature was raised to 1350℃ and held for 2 hours for ceramic metallization treatment. The final product had a density of 2.9 g / cm³. 3 C / SiC-ZrB2-HfB2-Cu composite material test block.

[0027] Example 3 Carbon aerogel powder (specific surface area 120m²) 2 A mixture of ZrB2 powder (particle size 500-800 nm), HfB2 powder (particle size 300-400 nm), water, and polyethyleneimine in a mass ratio of 1:6:1:150:0.2 was placed in a ball mill jar with 7 mm diameter zirconia balls at a ball-to-particle ratio of 4:1. The mixture was milled at 700 rpm for 12 hours to obtain a C-ZrB2-HfB2 slurry.

[0028] Then, vacuum centrifugation impregnation was performed, following the same steps as in Example 1. After impregnation, the sample was removed and dried at 150°C for 5 hours to obtain C. f / C-ZrB2-HfB2 blank (density 1.45g / cm³) 3 ).

[0029] The blank was placed in a graphite crucible and completely covered with silicon-copper alloy powder (particle size 0.3~0.5μm), with a silicon-copper atomic ratio of 4:1. The temperature was raised to 1350℃ and held for 2 hours for ceramic metallization treatment. The final product had a density of 2.9 g / cm³. 3 C / SiC-ZrB2-HfB2-Cu composite material test block.

[0030] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in the final ceramic metallization step, silicon powder (particle size 0.5~1μm) was used instead of silicon-copper alloy powder, the reaction temperature was raised to 1550℃, and the temperature was held for 2 hours, finally yielding a product with a density of 2.6 g / cm³. 3 C / SiC-ZrB2-HfB2 composite material test block.

[0031] Comparative Example 2 Use the traditional commercially available 2.7 g / cm³ 3 C / SiC-Cu composite material specimens (the specimens were prepared using a melt infiltration process, with a preparation cycle of 2 months).

[0032] Comparative Example 3 Use the traditional commercially available 3.0 g / cm³ 3 C / SiC-ZrB2 composite material specimens (the specimens were prepared using a precursor impregnation pyrolysis process, with a preparation cycle of 3 months).

[0033] Comparative Example 4 Use the traditional commercially available 4.5 g / cm³ 3 C / SiC-HfB2 composite material specimens (the specimens were prepared using a slurry impregnation + precursor impregnation pyrolysis process, with a preparation cycle of 2 months).

[0034] Comparative Example 5 Use the traditional commercially available 3.0 g / cm³ 3 C / SiC-ZrC-Cu composite material specimens (the specimens were prepared using a melt infiltration process, with a preparation cycle of 2 months).

[0035] The material properties of the examples and comparative examples are compared in Table 1.

[0036] Table 1 Performance Comparison

[0037] Note: The testing standards refer to the following standards: ASTM C559 (material density), GJB323A-oxyacetylene ablation (surface temperature and linear ablation rate of the ablation zone, ablation heat flux density 4MW / m³). 2 (Ablation time 300s), GB / T 6569-2006 (Bending strength of materials).

[0038] As shown in Table 1, under the same heat flux conditions, the composite material obtained by this invention exhibits significantly better thermal conductivity and cooling capacity, lower linear ablation rate, and higher mechanical properties compared to traditional composite materials. Compared to Example 2, Example 1 shows a reduction in HfB2 content and a slight increase in linear ablation rate, while the bending strength and cooling capacity remain essentially the same. Compared to Example 3, Example 2 shows a decrease in the specific surface area of ​​carbon aerogel powder in the reactants and a slight reduction in the dispersion dosage, but the resulting material properties are essentially the same. Comparison of the examples with comparative examples reveals that, compared to Comparative Example 1, the material surface temperature is lower and the linear ablation rate is superior after adding the conductive agent. Compared to Comparative Example 2, the addition of ultra-high temperature ceramic matrix components significantly improves the linear ablation rate. Compared to Comparative Examples 3 and 4, the composite material prepared using traditional processes exhibits a lower surface temperature, superior linear ablation rate, and significantly improved mechanical properties. Compared to Comparative Example 5, the addition of HfB2 components results in a lower surface temperature, superior linear ablation rate, and significantly improved mechanical properties. Figure 3 The macroscopic photographs of the ablation material show that the surface condition of the sample from the example is more intact.

[0039] Depend on Figure 4 and Figure 5 As shown, the composite material interface layer prepared in Example 1 is smooth and intact. Figure 4 (a) The ceramic phase is evenly distributed. Figure 4 (b) The fiber extraction effect is obvious. Figure 5 The Cu conductive agent forms a three-dimensional continuous network structure in the matrix, and the ZrB2-HfB2 particles are uniformly dispersed in the SiC matrix.

[0040] In summary, this invention successfully prepared a C / SiC-ZrB2-HfB2-Cu composite material with thermal conductivity through vacuum centrifugal impregnation and ceramic metallization processes, effectively solving the problems described in the background art. The material preparation cycle can be shortened to less than 15 days, which is more cost-effective than traditional SI (slurry impregnation) or PIP (precursor impregnation pyrolysis) processes. During the ceramic metallization reaction, the Cu alloy conductive agent precipitated in situ from the silicon-copper alloy can form a highly efficient heat conduction channel during ultra-high temperature service. On the one hand, the conductive agent rapidly conducts outward in the form of sweating under high surface heat flux, significantly reducing the surface temperature; on the other hand, the SiC-ZrB2-HfB2 ultra-high temperature ceramic has excellent ablation resistance. The two work synergistically to achieve a significant improvement in long-term ultra-high temperature heat protection performance, namely ablation resistance and low surface temperature.

Claims

1. A method for preparing a C / SiC-ZrB2-HfB2-Cu composite material, characterized in that, Includes the following steps: (1) Prepare C-ZrB2-HfB2 mixed slurry; (2) The carbon fiber preform with the pyrolytic carbon interface layer is placed in the mixed slurry prepared in step (1), vacuum centrifuged and impregnated, then removed and dried to obtain C f / C-ZrB2-HfB2 blank; (3) Take C from step (2) f The C / SiC-ZrB2-HfB2 blank was placed in a crucible and embedded with a silicon-copper alloy to obtain the C / SiC-ZrB2-HfB2-Cu composite material.

2. The method for preparing the C / SiC-ZrB2-HfB2-Cu composite material according to claim 1, characterized in that: In step (1), the preparation process of the C-ZrB2-HfB2 mixed slurry is as follows: carbon aerogel powder, ZrB2 powder, HfB2 powder, water and dispersant are mixed and ball-milled.

3. The method for preparing the C / SiC-ZrB2-HfB2-Cu composite material according to claim 2, characterized in that: The specific surface area of ​​the carbon aerogel powder is 100~300 m². 2 / g, with a particle size of 500~800nm, ZrB2 powder with a particle size of 300~500nm, and HfB2 powder with a particle size of 100~300nm; The dispersant is one or more of sodium tripolyphosphate, sodium polyacrylate, polyvinyl alcohol, polystyrene, and polyethyleneimine; The mass ratio of the carbon aerogel powder, ZrB2 powder, HfB2 powder, water, and dispersant is 1:(4~6):(1~2):(100~200):(0.1~0.5). The ball milling medium is zirconium oxide, the ball diameter is 4~10mm, the ball-to-material volume ratio is 4:1, the ball milling speed is 300~700rpm, and the ball milling time is 5-12h.

4. The method for preparing the C / SiC-ZrB2-HfB2-Cu composite material according to claim 1, characterized in that: In step (2), the carbon fiber preform adopts a fine-woven puncture structure, with a fiber volume content of 30-40% and a density of 0.55-0.75 g / cm³. 3 ; The pyrolytic carbon interface layer has a thickness of 2-5 μm; it is prepared using a chemical vapor infiltration process, with one or both of Ar and N2 as carrier and dilution gases, and one or both of natural gas and C3H8 as gaseous precursors, with a precursor concentration of 10%-50%; the deposition temperature is 900-1000℃, and the deposition time is 30-100 h; the density of the carbon fiber preform with the pyrolytic carbon interface layer is 0.8-1.2 g / cm³. 3 The C f The density of the / C-ZrB2-HfB2 blank is 1.45~2.0 g / cm³. 3 .

5. The method for preparing the C / SiC-ZrB2-HfB2-Cu composite material according to claim 1, characterized in that: In step (2), the process parameters for vacuum centrifugal impregnation are: vacuum degree ≤100Pa; rotation speed 300~500r / min; impregnation time 10~30h; The drying temperature is 150℃, and the drying time is 5~7 hours.

6. The method for preparing the C / SiC-ZrB2-HfB2-Cu composite material according to claim 1, characterized in that: In step (3), the silicon-copper alloy has a particle size of 0.3~0.5μm, a silicon-copper atomic ratio of (2~6):1, an embedding temperature of 1100~1400℃, and an embedding time of 1~3h.

7. A C / SiC-ZrB2-HfB2-Cu composite material prepared according to the preparation method of any one of claims 1-6.

8. The C / SiC-ZrB2-HfB2-Cu composite material according to claim 7, characterized in that: The density of the composite material is ≥2.8 g / cm³. 3 The Cu conductive agent forms a three-dimensional continuous network structure in the matrix, and the ZrB2-HfB2 particles are uniformly dispersed in the SiC matrix. During service, the surface temperature is 300~700℃ lower than that of traditional ceramic matrix composites.

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