Microstructure and properties of coating-matrix integrated C/(Hf, Zr, Ti)C-(Ti, Zr, Hf)₃SiC₂-SiC composites prepared via RMI process

C/(Hf, Zr, Ti)C-(Ti, Zr, Hf)₃SiC₂-SiC composites with Hf-Zr-Ti based in-situ coatings were prepared by RMI process utilizing HfSi₂-ZrSi₂-TiSi₂ hybrid alloy. The microstructure, mechanical properties, and ablation performance of the composites were investigated. The in-situ coating with (Hf, Zr, Ti)C-(Hf, Zr, Ti)Si₂ as main components was continuously integrated with the matrix. In the substrate, there were more Hf-rich (Hf, Zr, Ti)C in the marginal region and more Ti-rich (Ti, Zr, Hf)₃SiC₂ and SiC in the interior. The flexural strength of the composites was 225 ± 5.93 MPa and fracture toughness was 11 ± 0.85 MPa·m^1/2 under the effect of lamellar (Ti, Zr, Hf)₃SiC₂. After ablation for 60 s, the linear and mass ablation rates of the composites were −2.13 ± 0.91 μm/s and −0.97 ± 0.01 mg/s, respectively. The outstanding ablation resistance was attributed to the glassy SiO₂ promoting (Hf, Zr, Ti)O₂ sintering and liquid TiO₂ healing defects.