Precursor-Derived Porous Layered HfC Ceramic with High-Temperature Resistance and Excellent Electromagnetic Wave...

The demanding requirements of stealth components in advanced aircraft for extreme environments necessitate novel materials that integrate high-temperature resistance and efficient electromagnetic wave absorption. Among them, HfC ceramic possesses a high melting point of nearly 3900 °C. However, the poor impedance matching severely restricts its application in electromagnetic wave absorption. Precursor-derived ceramics (PDCs) offer a versatile platform for designing high-temperature-resistant materials with porous microstructures for improving impedance matching. Inspired by structural engineering strategies, this work presents a novel PDC route to fabricate a porous layered HfC ceramic. Specifically, the precursor was obtained by crushing and freeze-drying a gel that formed via the simultaneous self-assembly of GO and its in situ reaction with Hf(acac)₂(OH)₂ during the solvothermal reaction. Leveraging its high specific surface area, layered GO offers abundant -COOH/-OH that enables reactions with Hf-OH to form a stable Hf-O-C bond. This stable chemical bonding could create an intimate interfacial contact, reducing diffusion distances and enhancing carbothermal reduction for efficient HfO₂-to-HfC conversion. As a result, the porous HfC ceramic with a high hafnium content of 91.01 wt % was successfully obtained after pyrolysis at only 1400 °C. The resulting porous layered HfC ceramic retained its structural integrity up to 1800 °C. The pore structure was mainly constructed through the self-assembly of GO during the solvothermal reaction, ice crystal sublimation via freeze-drying, as well as subsequent high-temperature pyrolysis. Moreover, the porous layered HfC ceramic delivers outstanding electromagnetic wave absorption performance, attributed to the synergy effect between optimized impedance matching, conductive loss, and multiple polarization losses. Notably, it achieves a remarkable minimum reflection loss (RL_min) to a matching thickness ratio of -37.02 dB/mm, along with a radar cross section (RCS) attenuation value of 40.188 dB m² in simulation, demonstrating both strong intrinsic absorption and practical stealth capability. This work paves the way for the development of high-performance, integrated structural-functional materials for extreme applications.