Thermal protection mechanism of UHTCs-modified C/C composites in high temperature gas scouring coupling environments

Examining the coupling analysis between environment and material system is prerequisite for advancing the reliability design of thermal protection system components in aerospace applications. To elucidate the resistance of C/C composites to high-temperature gas-flow erosion, C/C–MeC–SiC composites (Me: Hf, Zr, Ti, Ta, Nb, W) were prepared by reactive melt infiltration. The thermal loading characteristics of DC plasma torch (Ar–O₂ atmosphere, 2500 °C) were simulated by finite element analysis, as well as the ablation resistance was analyzed theoretically and experimentally. The ablation-resistant behaviors of carbon-based composites were investigated by theoretical calculations and experimental verification. The results show that the higher temperature resistance of HfC (0.69 μm/s), ZrC (−1.58 μm/s) and their oxidation products become the primary mechanism for the skeletal support of the oxide layer. The high fluidity of TiO₂ rapidly forms an oxide layer but also exacerbates the volatilization of gaseous by-products (TiC, 3.02 μm/s). Due to the volatility of WO₃, WC is limited to short-term ablation resistance (−2.11 μm/s). The oxidation products of NbC and TaC are directional and are expected to rapidly fill the porous structure under thermal shock. Coupled fluid-thermal-structural simulations elucidate the heat flux density, temperature, and stress distributions of different systems of composites under heterogeneous ablation, consistent with the post-ablation morphological trends.