Ablation behaviors of C/SiC–(HfZrTi)C composites under various heat fluxes

C/SiC–(HfZrTi)C composites were fabricated via reactive melt infiltration, and their ablation behavior was systematically investigated under three heat fluxes (1.5, 3.0, and 4.5 MW/m²). Under low heat flux, a dense (HfZr)O₂ skeleton formed in conjunction with a SiO₂–TiO₂ glassy phase. The incorporation of TiO₂ stabilized the tetragonal phase through lattice distortion, thereby suppressing phase transformation during cooling. Under medium heat flux, (HfZr)TiO₄ evolved into island-like protrusions, and its limited incongruent melting promoted liquid-phase sintering. This process generated a robust network structure that enhanced resistance to aerodynamic shear forces, while the volatilization–redeposition cycle of Ti-rich species maintained the integrity of the oxide layer. Under high heat flux, extensive incongruent melting of (HfZr)TiO₄, combined with active oxidation, destabilized the skeleton structure and initiated spallation, ultimately leading to catastrophic failure. The findings reveal three distinct ablation regimes—stable growth, dynamic equilibrium, and catastrophic failure—and demonstrate the synergistic effects of HfC, ZrC, and TiC. These components provide exceptional performance under low and medium heat fluxes, while their structural degradation under high heat flux leads to rapid failure. This work provides a mechanistic framework for understanding the temperature-dependent behavior of multicomponent carbide composites.