Preparation and characterization of lightweight SiC frameworks by connecting SiC fibers with SiC joints

Abstract

The increasing energy challenges and the rapidly developing astronautic technology require thermal insulators with low density and thermal conductivity, high–temperature thermal, chemical and mechanical stabilities. Herein, highly porous SiC frameworks were fabricated through procedures of assembling SiC fibers and formation of SiC joints by carbothermal reduction, which were named as SiC–bonded SiC fiber (SBSF) composites. The porosities were controlled in the range of 76–93% by varying aspect ratios of the SiC fibers. The SBSF composites exhibited outstanding corrosion resistance, oxidation resistance, and high–temperature thermal stability, as the inherent advantages of SiC ceramics. High strength and reversible compressibility were obtained in the out–of–plane compression load tests, and low thermal conductivity of 0.036–0.102 W/m · K at 25–800 °C was achieved. The results of this study suggest that the SBSF composites are a good candidate for high–temperature thermal insulators.