Thermal-mechanical-electrical coupled hierarchical foam ceramics for multifunctional extreme environment thermal protection

Future multifunctional thermal protection materials for extreme environments should feature a dual-layer structure, with the outer layer as ablation-resistant materials and the inner layer as high-temperature-resistant multifunctional materials. This work presents an inner‑layer material, a foam ceramic with periodic nanofiber membrane intercalation (FCPN), that simultaneously achieves high‑temperature electromagnetic wave absorption, thermal insulation, and mechanical robustness. Through hierarchical pore engineering and electromagnetic‑thermal coupling design, the FCPN delivers a 36 GHz absorption bandwidth up to 1200 °C—the highest reported operating temperature for such absorbers—and a low thermal conductivity of 0.08 W·m⁻¹·K⁻¹ at only 9.2 mm thick. Compared with conventional foam ceramics, this represents a 718% bandwidth enhancement and a 70% reduction in thermal conductivity, while retaining a compressive strength of 6.65 MPa. Integrated with a wave‑transparent Si₃N₄ composite, the FCPN‑based thermal protection system withstands 1585 °C oxyhydrogen flame for 35 min and 2300 °C oxyacetylene flame for 20 s, demonstrating unified ultra‑broadband absorption, thermal management, and load‑bearing capacity for hypersonic stealth skins.