Ablation behavior of C/C composite matrix-modified with solid solution ceramic TaZr2C3-SiC under an oxyacetylene flame

The oxide layer that forms on the surface of C/C composites matrix-modified with multiphase ultra-high temperature ceramics is generally loose and poorly bonded, limiting its effectiveness in enhancing the ablation resistance of C/C composites. In this study, C/C composites were matrix-modified using solid solution ceramic TaZr 2 C 3 -SiC and multiphase ceramic TaC-2ZrC-SiC, both with the same Zr/Ta ratio. The C/C-TaZr 2 C 3 -SiC and comparative sample C/C-TaC-2ZrC-SiC composites were prepared through a high-solid-loading slurry impregnation method combined with a precursor infiltration and pyrolysis process. The flexural properties were evaluated, and ablation tests were conducted under an oxyacetylene flame. Compared to C/C-TaC-2ZrC-SiC, the C/C-TaZr 2 C 3 -SiC sample exhibited superior flexural properties and ablation resistance. The flexural strength, elastic modulus, and fracture toughness improved by 10.80%, 29.75%, and 37.67%, respectively. The mass and linear ablation rates were reduced by up to 85.49% and 77.26%, respectively. The superior ablation resistance of C/C-TaZr 2 C 3 -SiC was attributed to the formation of the anti-ablation microstructure composed of the Ta-rich oxide binder phase and Zr-rich oxide skeleton phase in the Ta-Zr-O oxide layer. The microstructure enhanced the viscosity of the oxides and strengthened their interfacial bonding, effectively suppressing the splashing and consumption of surface oxides under high heat flux while preventing their accumulation in the brim ablation region. The oxide layer was more compact and tightly bonded to the composite surface, providing the composites with significantly improved ablation protection. These findings provide a novel and effective approach for further improving the ablation resistance of C/C composites.