Biomimetic Flexible SiC/SiOx Microribbon Aerogels for Thermal Insulation and Electromagnetic Wave Absorption in Extreme Environments.

Silicon carbide (SiC) aerogels are attractive protective materials for extreme environments owing to their low density, thermal stability, thermal insulation, and electromagnetic wave attenuation. However, conventional SiC aerogels assembled from rigid nanoparticle-chain skeletons are intrinsically brittle and lack reversible deformability, limiting their use under complex service conditions. Herein, inspired by the heterogeneous trunk-flower-cluster architecture of kapok trees, a biomimetic flexible SiC/SiOx microribbon aerogel (SMA) is developed via carbon-felt-template-assisted in situ reaction growth followed by controlled thermal oxidation. The aerogel features a hierarchical porous network composed of interconnected SiC/SiOx microribbons and SiC clusters, with an ultralow density of 0.02 g cm-3 and a porosity above 99%. Benefiting from the highly porous microribbon-cluster framework, SMA exhibits a low thermal conductivity of 0.035 W m-1 K-1 at room temperature and robust high-temperature thermal insulation under direct flame heating. Moreover, the flexible SiC/SiOx microribbons and rigid SiC cluster nodes enable reversible bending up to 150° and recoverable compression up to 40%. The optimized heterogeneous structure further improves impedance matching and interfacial/dipolar polarization loss, delivering a 4.0 GHz effective absorption bandwidth at 5.0 mm. This work offers a structural strategy for flexible, lightweight, multifunctional SiC aerogels for integrated thermal and electromagnetic protection in extreme environments.