Preparation and ablation behavior of solid solution ceramic Ta0.2Zr0.8C-SiC matrix-modified C/C composites under high heat flux

To further enhance the ablation resistance of C/C composites, solid solution ceramic Ta 0.2 Zr 0.8 C was used to replace traditional ultra-high-temperature ceramic carbides for matrix modification of C/C composites. The C/ C-Ta0.2Zr0.8C-SiC composite was fabricated by a high-solid-loading slurry impregnation combined with the precursor infiltration and pyrolysis process. The comparative samples of C/C-ZrC-SiC and C/C-TaC-SiC were also prepared using these same technologies. The microstructure, flexural properties, and ablation performance of the composite were investigated. Results showed that the C/C-Ta0.2Zr0.8C-SiC exhibited excellent overall flexural properties. During the ablation test under an oxyacetylene flame with high heat flux, the ablation resistance of C/C-Ta0.2Zr0.8C-SiC improved with prolonged ablation time, reaching mass and linear ablation rates of 0.67 mg/s and 0.18 mu m/s after 120 s of ablation. Compared to the C/C-ZrC-SiC and C/C-TaC-SiC, the mass ablation rate of the composite was reduced by 49.24% and 68.70%, and the linear ablation rate was reduced by 97.22% and 97.71%, respectively. The enhanced ablation resistance was primarily attributed to the formation of the Ta-Zr-O oxide layer, composed of TaZr2.75O8, ZrO2, and Ta2O5, on the composites surface. In the oxide layer, the Ta-rich oxides served as a binder, filling gaps in the interface. Meanwhile, the Zr-rich oxides formed the skeleton that pinned the molten liquid oxides. The combined effects of Ta-rich and Zr-rich oxides made the Ta-Zr-O oxide layer more compact and strongly bonded to the matrix.