Lightweight and resilient SiBCNa/mullite/SiCnw composite for thermal insulation and electromagnetic wave absorption

Owing to tunable dielectric properties, light weight and high porosity, polymer-derived SiBCN ceramic aerogels possess significant application prospects in electromagnetic wave (EMW) absorption and thermal insulation. However, the poor mechanical properties and brittleness severely limit the practical applications of SiBCN aerogels. Herein, to address this issue, a SiBCN aerogel/mullite fiber/SiC nanowire (d was developed by using mullite fiber felt as a skeleton and incorporating in-situ synthesized SiC nanowires. The resulting composite demonstrates excellent mechanical properties and resilience, with no obvious plastic deformation after 200 cycles of compression test at a 40 % strain. Additionally, the composite shows a low thermal conductivity of 0.041 W/mK and a low density of 0.188 g/cm3. More importantly, the SiBCNa/mullite/SiCnw composite exhibits outstanding EMW absorption performance, with a minimum reflection loss of -40.3 dB. The present work paves the way for developing microwave absorption and thermal insulation integrated material for high-speed vehicles.