Ablation Behavior of the SiC-Coated Three-Dimensional Highly Thermal Conductive Mesophase-Pitch-Based Carbon-Fiber-Reinforced Carbon Matrix Composite under Plasma Flame

This study is focused on a novel high-thermal-conductive C/C composite used in heat-redistribution thermal protection systems. The 3D mesophase pitch-based carbon fiber (CF(MP)) preform was prepared using CF(MP) in the X (Y) direction and polyacrylonitrile carbon fiber (CF(PAN)) in the Z direction. After the preform was densified by chemical vapor infiltration (CVI) and polymer infiltration and pyrolysis (PIP), the 3D high-thermal-conductive C/C (C(MP)/C) composite was obtained. The prepared C(MP)/C composite has higher thermal conduction in the X and Y directions. After an ablation test, the CF(PAN) becomes needle-shaped, while the CF(MP) shows a wedge shape. The fiber/matrix and matrix/matrix interfaces are preferentially oxidized and damaged during ablation. After being coated by SiC coating, the thermal conductivity plays a significant role in decreasing the hot-side temperature and protecting the SiC coating from erosion by flame. The SiC-coated C(MP)/C composite has better ablation resistance than the SiC-coated C(PAN)/C composite. The mass ablation rate of the sample is 0.19 mg·(cm(−2)·s(−1)), and the linear ablation rate is 0.52 μm·s(−1).