Synthesis of C/Sic Aerogel Composites with Enhanced Mechanical and Antioxidant Properties for High Temperature Insulation

Abstract

High-temperature thermal-insulation aerogels with high mechanical strength and well oxidation resistance is critical for the thermal protect system (TPS) of aerospace vehicles. However, it is still challenging to achieve large-scale preparation of aerogels that integrate the above functions through a simple method. In this work, carbon fiber (CF) felts are introduced as a reinforcement and template to prepare CF-reinforced SiC nanowire aerogel composites through a simple in-situ growth strategy. The high-strength CF as the skeleton endows high mechanical strength, and the in-situ grown SiC nanowire aerogels lead to good thermal insulation of the composites. More importantly, a dense SiC shell was also formed and tightly coated on the surface of CF during the in-situ growth process, which effectively protects the CF from oxidation, thus enhancing the high temperature oxidation resistance of the composites. As a result, the optimal composites possess a low thermal conductivity of only 0.056 W·m-1·K-1 at room temperature and a high Young’s Modulus up to ~129.61 MPa. The back temperature of the 9 mm thick composites is only 151.9 ℃ after exposure to a butane flame at 1220 ℃ for 300 s, and it still maintains considerable thermal insulation and mechanical properties after the ablation. In addition, the machinability of the CF felt template makes it easy to prepare the composites in various shapes and larger sizes. This work provides a simple and scalable strategy to synthesize reliable SiC-based aerogel composites for high-temperature thermal insulation applied in extreme environments.

Keywords: silicon carbide aerogels, carbon fiber composites, mechanical strength, thermal insulation, stacking faults, oxidation resistance