Abstract:C/C-ZrC-SiC composites with different ZrC-SiC contents were fabricated by precursor infiltration and pyrolysis. The effect of ceramic content on the microstructure and ablation resistance was investigated. Both the C/C-SiC and C/C-ZrC-SiC composites exhibited good ablation resistance under the plasma flame above 2300 °C. With the increase of ZrC content, a continuous oxide layer and a solid Zr-Si-O mesophase were formed during the ablation. And the structure of the formed oxides layer closely linked with the contents of ZrC-SiC ceramics. The solid ZrO₂-ZrC and Zr-Si-O mesophase could increase the viscosity of SiO₂ moderately and improve the anti-scouring ability. The continuous SiO₂-ZrO₂-ZrC-SiC layer would serve as a thermal and oxygen barrier for preventing the substrate from further ablation. The C/C-ZrC-SiC composites with 27.2% ZrC and 7.56% SiC shows superior ablation resistance, and the mass and linear ablation rates are -3.51 mg/s and -1.88 μm/s, respectively.

Key words: C/C composites; ZrC; SiC; ablation; precursor infiltration and pyrolysis