Ablation behavior and mechanism of C/C-ZrC-SiC composites under an oxyacetylene torch at 3000 °c

C/C-ZrC-SiC composites with continuous ZrC-SiC ceramic matrix were prepared by a multistep technique of precursor infiltration and pyrolysis process. Ablation properties of the composites were tested under an oxyacetylene flame at 3000 °C for 120 s. The results show that the linear ablation rate of the composites was about an order lower than that of pure C/C and C/C-SiC composites as comparisons, and the mass of the C/C-ZrC-SiC composites increased after ablation. Three concentric ring regions with different coatings appeared on the surface of the ablated C/C-ZrC-SiC composites: (i) brim ablation region covered by a coating with layered structure including SiO₂ outer layer and ZrO₂-SiO₂ inner layer; (ii) transition ablation region, and (iii) center ablation region with molten ZrO₂ coating. Presence of these coatings which acted as an effective oxygen and heat barrier is the reason for the great ablation resistance of the composites.