Biomimetic hollow SiC fiber network with hierarchical layered architecture via template-assisted in situ coating for high-temperature insulation

Porous thermal insulators are vital for aerospace and energy systems, yet achieving a balance between lightweight architecture, mechanical robustness, and stability under oxidizing high-temperature conditions remains a significant challenge. Here, a biomimetic strategy was developed to construct hollow silicon carbide fibers (SiC-HF) using carbon fiber felt as a template. Continuous SiC coatings were formed in situ and the carbon core was selectively removed, yielding an ultralight porous network with a density of 0.033 mg·cm −3 and a porosity of 97.6 %. The hierarchical hollow-fiber architecture imparted exceptional elasticity to the SiC-HF, enabling recovery after compressions of up to 40 % strain and preserving structural integrity across both cryogenic and high-temperature conditions. In addition, the multiscale pore system suppressed gas-phase and solid-phase conduction while attenuating radiative transfer, resulting in a low thermal conductivity of 0.0692 W·m −1 ·K −1 at room temperature and stable insulation at elevated temperatures. Moreover, the SiC-HF exhibits strong oxidation resistance, showing only 24.65 % mass change at 1300 °C for 2 h. This work offers a robust pathway to oxidation-resistant porous ceramics and delivers valuable design insights for developing next-generation thermal protection materials suited to extreme environments.