Ablation mechanism of C/C–SiC composites in supersonic oxygen‐enriched ablation environment for the internal flow field

Abstract

AbstractThis study investigates the ablation resistance of C/C–SiC composites using the ground simulation internal flow‐field supersonic oxygen‐rich ablation test technology. The microstructure evolution and ablation mechanism of the composites in a supersonic oxygen‐rich environment were explored by examining the macroscopic and microscopic ablation morphologies of the composites before and after the test. The results demonstrate that C/C–SiC composites exhibit excellent ablation resistance, with mass and linear ablation rates of .46 × 10−2 g/s and .42 × 10−2 mm/s, respectively, after 120 s of ablation in a low gas temperature and high oxygen‐rich ablation thermal environment. As the gas temperature increases, the mass and linear ablation rates of C/C–SiC composites gradually increase, even though the oxygen enrichment within the gas components decreases. When the gas temperature reaches 2178–2491 K, the mass and linear ablation rates increase to 1.31 × 10−2 g/s and .84 × 10−2 mm/s, respectively. Furthermore, at high temperatures above 2650 K, the mass and linear ablation rates of the composites exhibit a geometric multiple increase, reaching 4.73 × 10−2 g/s and 1.89 × 10−2 mm/s, respectively. These findings indicate that the ablation resistance of C/C–SiC composites in the supersonic oxygen‐rich ablation environment is more sensitive to gas temperature than oxygen enrichment. The main factors contributing to the increased ablation rate of C/C–SiC composites in the supersonic oxygen‐rich ablation process include the formation of a glass SiO2 oxide film, transition to molten SiO2, erosion of molten SiO2, and high‐temperature sublimation of the SiC matrix.