Multiscale SiC fiber/nanowire aerogels for broadband electromagnetic wave absorption via scalable ceramic papermaking coupled with CVI

Abstract The escalating demand for multifunctional thermal protection systems (TPSs) necessitates advanced materials that concurrently withstand extreme environments and mitigate electromagnetic wave (EMW) radiation. However, single-scale coarse fiber frameworks often suffer from limited polarization interfaces and loose mechanical interlocking. To address this, by coupling a scalable room-temperature ceramic papermaking strategy with chemical vapor infiltration (CVI), we fabricate multiscale all-ceramic SiCf/SiCnw aerogels (SFWs) that seamlessly bridge millimeter-scale fibers to nanoscale nanowires. Operating entirely under ambient conditions without the need for size-limiting equipment, this highly scalable and versatile strategy enables the fabrication of large-area components with arbitrary geometries. Optimizing the matrix fiber length to 5 mm unlocks sufficient interfiber void space for the uniform proliferation of ultrahigh-aspect-ratio SiC nanowires. The resulting SFW-5 M aerogel achieves an ultralow density of merely 0.23 g·cm−3 alongside an exceptional minimum reflection loss (RLmin) of −46.62 dB. Under 1000 °C flame exposure, the back-surface temperature is reliably restricted to approximately 250 °C. Crucially, rather than undergoing catastrophic embrittlement, prolonged ablation triggers a striking “fire-strengthening” effect, simultaneously enhancing compressive peak stresses and expanding the effective absorption bandwidth (EAB) to 11.5 GHz—effectively spanning the C, X, and Ku bands (72% of the 2–18 GHz range). Driven by cross-scale synergy between the fibrous scaffold and nanowire network, these durable aerogels overcome the inherent limitations of single-scale scaffolds, offering a scalable paradigm for next-generation aerospace TPS design.