Ablation and mechanical behavior of reusable C_f/SiC-ZrC with a gradient-structured matrix produced by reactive melt infiltration

C_f/SiC-ZrC renowned for its outstanding performance as a thermal protectant, has gaining widespread recognition. Recent research on this system has emphasized the development of a cost-effective and reusable version with increased thickness for extended use in thick-walled thermal structural components. Ablation resistance, high strength retention, and high thermal conductivity are crucial for successful aircraft reentry. In this study, a low-cost reactive melt infiltration (RMI) method is developed for preparing dense and high-performance large-thickness C_f/SiC-ZrC (L-C_f/SiC-ZrC) with a gradient-structured matrix. The use of a fine weave-pierced fabric preform structure enhances both the structural integrity and thermal conductivity of C_f/SiC-ZrC in the thickness direction. Simultaneously, the gradient-structured matrix, with appropriate contents of surficial ZrC and SiC exhibits erosion resistance, where the internal core with a high SiC content ensures remarkable strength retention. This unique matrix-structure design is achieved by integrating porous C with a single-stage pore structure and a high degree of graphitization degree, and a Si-Zr alloy with a unique composition. The 20 mm thick C_f/SiC-ZrC obtained via RMI has a density of 2.79 g/cm³ with an open porosity of 5.65 % and flexural strength of 224.3 ± 5.4 MPa. Under a heat flux of 4.186 MW/m², C_f/SiC-ZrC exhibits an ablation rate of −0.004 mm/s after 60 s, demonstrating its resilience against ablation damage. Moreover, the post-ablation strength (166.0 ± 4.4 MPa) exceeds that of reported C_f/SiC-ZrC congeners, highlighting the robust load-bearing capability.