Lightweight and multifunctional SiC aerogel with hollow microtube-nanowire hybrid structure for thermal shielding and electromagnetic wave absorption

Hypersonic thermal protection requires materials with thermal shielding and electromagnetic wave absorption capabilities. While silicon carbide (SiC) aerogel is a promising candidate due to their dielectric properties, porosity, and thermal stability, the conventional forms face an intrinsic trade-off between microwave absorption and thermal insulating. Inspired by natural hollow structure of reeds, this work proposes a novel in-situ growth technique combined with a sacrificial-template process to fabricate a lightweight SiC-based composite aerogel featuring a unique hollow microtube-nanowire hybrid architecture (SCN-SCH). Impressively, the hollow microtubes, in synergy with the nanowire network and optimized SiC content, contribute to enhanced electromagnetic wave absorption through improved impedance matching and abundant heterogeneous interfaces. Crucially, this hollow architecture achieves substantially improved insulation performance while preserving the ultralow density (0.038 W/(m·K) thermal conductivity) and mechanical robustness (70% compressibility, resilience over 50 cycles) of the aerogel. Moreover, this multiscale structure of SCN-SCH aerogel delivers a broadband absorption band extending to 3.9 GHz at a thickness of 2.6 mm and a minimum reflection loss of −59.37 dB. This study not only provide a bioinspired multiscale engineering strategy of SiC aerogels to effectively improve the conflict between thermal insulation and microwave absorption, but also offers a new design paradigm for high-performance multi-functional materials in extreme environments.