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

Abstract

<p>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. <br></p>