Effect of ZrC particle size on the ablation resistance of C/C-ZrC-SiC composites

C/C-ZrC-SiC composites with different ZrC particle size was fabricated by organic precursor infiltrations and pyrolysis (PIP) combined with additional heat treatment at different temperatures and further PIP of SiC precursor. Effect of ZrC particle size on the ablation resistance of C/C-ZrC-SiC composites was investigated under heat flux of 4.18 ± 0.42 MW/m² containing high scouring. Results showed that small ZrC particle size (0.2 μm) caused low viscosity and unfavorable anti-scouring of the formed oxides, leading to unsatisfactory ablation resistance of the composites. Oxides for composites with big ZrC particles (2 μm) failed to seal large gaps between ZrC particles, resulting in massive ablation of the composites. Composites with ZrC particle size of around 1 μm showed good ablation resistance, with linear ablation rate decreased by 91.3% relative to C/C-ZrC-SiC composites with ZrC particle size of 200 nm. The good ablation resistance was mainly ascribed to the formed viscous oxides containing particles, which could resist scouring and meanwhile seal gaps in composites during ablation.