通过化学气相渗透法和先驱体浸渍裂解法相结合制备出密度为1.95 g/cm3的三维 C/C-HfC 复合材料,碳化铪陶瓷相均匀地填充于材料内部.探究了先驱体的物相转化过程和材料的耐烧蚀性能.结果表明:复合材料经等离子体烧蚀装置测试120 s后,样品的质量烧蚀率和线烧蚀率分别为:0.001 5 g/s和0.002 4 mm/s.通过先驱体浸渍裂解工艺引入到基体内的碳化铪陶瓷相在烧蚀过程中与氧化性气体生成的二氧化铪固体颗粒起既能起到一定的热障作用,也能作为抑制氧化性气体扩散的阻挡层,从而提高了材料的耐烧蚀性能.同时,氧化产物的生成和一氧化碳气体的挥发将消耗烧蚀区域内一部分热量,进而降低材料表面的温度,进一步提高材料的抗烧蚀能力.
A three-dimensional C/C-HfC composite with a density of 1.95 g/cm3 was fabricated by chemical vapor infiltration of carbon into a 3D woven carbon fiber felt to a density of 1.45 g/cm3 followed by vacuum impregnation and pyrolysis of a solution containing the HfC precursor.Results indicate that HfC particles are uniformly dispersed around the pyrocarbon.The 3D C/C-HfC composite exhibits a good ablation resistance at 2573 K.The mass and linear ablation rates after ablation for 120 s are 0.001 5 g/s and 0.002 4 mm/s, respectively.The resistance to ablation is attributed to the introduction of HfC into the C/C composite.The tree-coral-like HfO2 particles formed during the ablation act as thermal and oxygen diffusion barriers, protecting the composite from further ablation.Also, the oxidation of HfC and the volatilization of the ablation product (CO) absorb a large amount of heat from the composite.
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