Construction of C/SiC–Cu3Si–Cu interpenetrating composites for long-duration thermal protection at 2500 °C by cooperative active-passive cooling

Developing materials which can resist long-term ablation at ultra-high temperatures above 2200 °C in oxygen-containing environments is of prime importance for the thermal protection of aerospace vehicles, but remains a great challenge. C/SiC composites are attractive candidates for long-term use, but they are often severely ablated above 1650 °C due to the damage of protective oxide scale. Here, C/SiC–Cu3Si–Cu interpenetrating composites with interconnected ceramic and metal matrixes are developed by the selective ceramization of carbon-fiber reinforced carbon aerogel preforms. The heat radiation of C/SiC–Cu3Si–Cu, transpiration of Cu2O, evaporation of SiO2, as well as inhibition of oxygen diffusion in the glassy scale, jointly lead to the cooperative active-passive cooling during ablation. Resultantly, their surface temperatures are 150 °C, 450 °C and 750 °C lower than those for C/SiC (1900 °C, 2200 °C and 2500 °C) with a duration of 600 s ablation, respectively. They also exhibit remarkably low mass and linear ablation rates with respective 0.054–0.064 mg cm−2 s−1 and -0.157–0.018 μm s−1. Additionally, the composites can endure 1160 s ablation with a surface temperature of 1750 °C under the ablation condition where the surface temperature of C/SiC is 2200 °C. The developed C/SiC–Cu3Si–Cu interpenetrating composites are so far the only known light-weight (<3.0 g cm−3), non-ablation materials which can offer long-duration (≥600 s) thermal protection at 2200–2500 °C in high-enthalpy-flow and oxidizing environments.