烧蚀时间对C/C-SiC复合材料高超声速富氧环境烧蚀机制的影响

为了研究烧蚀时间对C/C-SiC复合材料在高超声速富氧环境下烧蚀机制的影响规律，采用富氧环境下的高超声速烧蚀试验技术，对“化学气相渗透+先驱体浸渍裂解”混合工艺制备的针刺C/C-SiC复合材料动态烧蚀机制进行研究，并采用电子扫描显微镜观察烧蚀表面形貌。研究表明:在极端苛刻的高超声速富氧烧蚀环境下，C/C-SiC复合材料能够短时抵抗高温、高压、高超声速燃气射流的氧化工作环境。材料经高超声速富氧烧蚀10 s、20 s、30 s、40 s及50 s后的质量烧蚀率分别为0.021 g/s、0.025 g/s、0.027 g/s、0.026 g/s与0.034 g/s。C/C-SiC复合材料在高超声速富氧环境下的动态烧蚀行为主要受热化学烧蚀与机械剥蚀两种烧蚀机制共同作用。在初始阶段，SiO₂保护膜的存在有效阻止了氧化性组分向基体内部的扩散，仅材料中心区域存在轻微热化学烧蚀；烧蚀试验中期，材料的烧蚀主要表现为热化学烧蚀与机械剥蚀联合作用，并由热化学烧蚀向机械剥蚀呈渐变性转变；烧蚀试验后期，基体的深度反应使得材料的烧蚀主要表现为纤维与基体的大面积片状剥落。 

Effect of ablation time on ablation mechanism of C/C-SiC composites in hypersonic and oxygen-enriched environment

In order to study the effect of ablation time on the ablation mechanism of C/C-SiC composites under a hypersonic oxygen-rich environment, the dynamic ablation mechanism of the needled carbon/carbon-silicon carbide composites prepared by “chemical vapor infiltration + precursor immersion pyrolysis” hybrid process was studied by the hypersonic oxygen-enriched ablation test technology in this paper, and the ablation surface morphology of the composites were investigated by scanning electron microscopy. The results show that, the C/C-SiC composites can resist the oxidation working environment of high temperature, high pressure and hypersonic gas jets in a short time under the extremely harsh hypersonic oxygen-enriched ablation environment. The mass ablation rate of C/C-SiC composites after 10 s, 20 s, 30 s, 40 s and 50 s ablation by hypersonic oxygen-enriched ablation are 0.021 g/s, 0.025 g/s, 0.027 g/s, 0.026 g/s and 0.034 g/s, respectively. The dynamic ablation behavior of the C/C-SiC composites under the hypersonic oxygen-enriched environment is synergistic effects of thermo-oxidation ablation and mechanical erosion. In the initial stage, the existence of the SiO₂ protective film effectively prevents the diffusion of oxidizing components into the matrix, and only the central area of the material is slightly thermal oxidative ablation. In the middle test, the ablation of the material is mainly manifested in the combined effect of thermo-oxidation ablation and mechanical erosion, and gradually transition from mainly thermal oxidative ablation to mainly mechanical erosion. In the later stage of the ablation test, the further reaction of the matrix makes the ablation mechanism of the material mainly manifested as the large-area flaking of the fiber and matrix.