Effect of surface air cooling on the high frequent cyclic ablation of C/C-SiC-AlSi composite prepared by slurry injection technique

C/C-SiC-AlSi composites with uniform distribution of SiC ceramic phase were prepared by ultrasound-assisted slurry injection combined with the PIP+PI process. Ablation tests were performed by alternant plasma and surface cooling airflow for 0.2 s×200 cycles under the flame temperature of 2600 K. Results showed that the mass and linear ablation rates continued to decrease with the increasing of airflow rate from 0 to 3 m³/h, the minimum ablation rates were 0.1525 mg/s and 3.1725 μm/s, respectively. Micro-morphologies and surface temperature analysis suggested that ablation behavior of the composites was affected by the cooling effect of airflow and mechanical erosion. On the one hand, surface temperature of composites reduced and local physical and chemical reactions of the composites alleviated; on the other hand, the increase of airflow rate caused surface cracks and fragments of the composites. According to the ablation results, the former should play a leading role more than the latter.