Hyperelastic and multifunctional SiC/SiO2 composite aerogels with excellent mechanical, thermal insulation and electromagnetic wave absorbing properties

Abstract

SiC (silicon carbide) aerogels have attracted extensive attention due to their excellent thermal stability and large porosity. But at present, the serious challenge of SiC aerogel application is still poor mechanical properties. To address the above challenge, here we report SiC/SiO2 composite aerogels (SSCAs) with a mutually supported dual-network structure. SiO2 nanoporous networks are introduced into SiC networks to achieve the multifunctional properties, including mechanics, thermal insulation and electromagnetic wave absorption properties. Benefiting from the dual-network structure, the maximum compressive stress of the SSCAs is increased to 2551 kPa. In addition, SSCAs can withstand a large elastic strain of up to 60 %. Furthermore, the SSCAs exhibit an ultra-low thermal conductivity of 0.023 W·m−1 K−1 at room temperature. More importantly, SiC/SiO2 heterointerface structure optimizes impedance matching, resulting in an effective absorption bandwidth of 6.5 GHz. This work provides new ideas and insights for the preparation of multifunctional ceramic aerogels.