The rapid advancement of hypersonic vehicles has created an urgent demand for lightweight, multifunctional thermal protection systems (TPS) capable of withstanding extreme temperatures while simultaneously absorbing electromagnetic wave (EMW) radiation. Silicon carbide (SiC) aerogels have long been recognized as promising candidates due to their high melting point, exceptional oxidation resistance, and tunable dielectric properties. However, conventional single-scale SiC architectures, whether coarse fiber networks or sparse nanowire scaffolds, inevitably face a fundamental performance bottleneck: coarse fibers lack sufficient polarization interfaces for effective EMW attenuation, while fine nanowires lack macroscopic structural durability and thermal stability. This "fish‑and‑bear‑paw" dilemma has long hindered the integration of efficient wave absorption and reliable thermal insulation in a single material system. Fabrication challenges further compound the problem, as traditional sol-gel routes require energy-intensive supercritical drying and high-temperature sintering that are difficult to scale for large-area or arbitrarily shaped components.
Recently, a team of material scientists led by Professor Rujie He from Beijing Institute of Technology, China, reported a novel multiscale all-ceramic composite framework for multifunctional thermal protection and EMW absorption. This material consists of an ultralight SiCf scaffold assembled via room-temperature ceramic papermaking and inter-fiber grown SiCnw, subjected to CVI processing. By modulating the matrix fiber length to 5 mm (SFW‑5M), the team successfully created open macropores of hundreds of micrometers that eliminate gas transport barriers, allowing uniform growth of ultra‑high‑aspect‑ratio SiC nanowires within the inter‑fiber voids. The resulting SFW‑5M aerogel exhibits an ultralow density of merely 0.23 g·cm-3 and an exceptionally low room‑temperature thermal conductivity of 64 mW·m-1·K-1. This work highlights the advantages of multiscale structural design and confirms the superior wave attenuation and fire-strengthening mechanism of the hierarchically cross-linked fiber/nanowire interfaces.
The team published their work in Journal of Advanced Ceramics on August 21, 2026.
"Inspired by traditional Chinese papermaking technology, our room-temperature ceramic papermaking route allows SiC fibers to undergo gravity-driven self-assembly under ambient conditions without requiring size-limiting equipment, pressure, or high-temperature sintering. This yields a highly flexible precursor platform capable of producing large-format components with complex geometries," said Rujie He, professor at Institute of Advanced Structure Technology, Beijing Institute of Technology (China).
By modulating the matrix fiber length to 5 mm (SFW-5M), the team successfully unlocked sufficient open macroporous clearance across hundreds of micrometers. "This open scaffold eliminates gas transport barriers, allowing ferrocene-catalyzed VLS growth to uniformly grow ultra-high-aspect-ratio SiC nanowires within the inter-fiber voids." said Rujie He. The resulting SFW-5M aerogel exhibits an ultralow density of merely 0.23 g·cm-3 and an exceptionally low room-temperature thermal conductivity of 64 mW·m-1·K-1.
In thermal protection testing, the multiscale aerogel demonstrated outstanding thermal shielding. When subjected to direct exposure under a 1000 °C butane flame, the back-surface temperature of the 8 mm thick SFW-5M specimen was reliably restricted to approximately 250 °C—a 75% reduction relative to the heat source. "While coarse fibers block thermal radiation at high temperatures, the fine nanowire network suppresses gas-phase heat convection, conferring superior thermal insulation." explained Rujie He. Post‑ablation structural integrity was maintained without spallation, confirming excellent high‑temperature stability.
"The multiscale architecture achieves seamless cooperation across scales. At the macroscale, the millimeter fibers form primary channels for continuous wave scattering. At the micro- and nanoscales, the dense nanowires create interconnected 3D conductive pathways and abundant heterogeneous interfaces, driving intense interfacial and dipolar polarization." explained Rujie He.
After introducing nanowires, SFW‑5M achieved an impressive minimum reflection loss (RLmin) of -46.62 dB. Crucially, rather than undergoing catastrophic mechanical collapse or functional degradation during high-temperature service, exposure to 1000 °C air ablation for 1 hour triggered a striking "fire-strengthening" phenomenon. Post-ablation compressive peak stress increased significantly, while the Effective Absorption Bandwidth (EAB) expanded from 4.6 GHz to an extraordinary 11.5 GHz—spanning 72% of the 2-18 GHz range and fully covering the C, X, and Ku radar bands. "During high-temperature ablation, thermal oxidation forms a thin, amorphous SiO2
