Hierarchical SiC fiber aerogel toward microwave attenuation and thermal insulation application

Materials with structural hierarchy have drawn great attenuation due to their fascinating physical and mechanical properties given by the unique microstructures. In this study, hierarchical SiC fiber aerogel was successfully developed via a simple method by using carbonized silk fiber mat as a template and subsequent in-situ growth of SiC nanowires array through carbothermal reduction at high temperature. The formation mechanisms of hierarchical SiC fiber aerogel based on a vapor-solid-liquid process were discussed. Owing to the highly porous structure supported by SiC nanowires, the aerogel could show an ultralight density of 0.04 g/cm 3 and a compression fatigue resistance of 10 cycles at 40% strain with small and stable energy loss coefficients. The electromagnetic (EM) investigation suggests that the aerogel could serve as a wideband microwave attenuator with a minimal reflection loss (RL) of − 68 dB and a maximum effective attenuation bandwidth (EAB, RL<−10 dB) of 7.2 GHz when embedded in silicone matrix at 10 wt% loading ratio. Additionally, the hierarchical SiC fiber aerogel reveals remarkably low thermal conductivity of 0.027 W/m·K, suggesting enormous potential for thermal insulation. • Hierarchical SiC fiber aerogel have been fabricated by in-situ grown synthesis method. • Lightweight, wideband microwave absorber with low thermal conductivity is obtained. • The effects of hierarchical structure on the enhanced performance are elaborated.