Lightweight and thermally insulating ZnO/SiC_nw aerogel: A promising high temperature electromagnetic wave absorbing material with oxidation resistance

Enhancing the microwave attenuation performance under high-temperature and oxidative conditions is a forefront issue for electromagnetic absorption materials. SiC nanowire material exhibits great potential due to its superior thermal stability and oxidation resistance. While, the relatively poor dielectric loss limits its further application as a high effective absorber. In this study, the strategy of laminated porous structure design, as well as the composition of ZnO nanocrystals were applied to promote the microwave attenuation capacity. A simple dual hydrolysis reaction method was employed to grow ZnO nanocrystals on SiC nanowires, followed by the preparation of a 3D layered structure of ZnO/SiC_nw aerogel material using directional solidification processes. The ZnO/SiC_nw aerogel demonstrated effective broadband attenuation (>90 %) across the entire X-band from room temperature to 873 K. Moreover, the material chemistry remained constant at temperatures as high as 1073 K in air. It exhibited ultralightweight properties and possessed a low thermal conductivity of approximately 0.056 W/m·K, with a density of 0.167 g/cm³. The combination of its lightweight, oxidation resistance, thermal insulation, and attractive X-band absorption efficiency positions ZnO/SiC_nw aerogel as a promising EM absorption candidate at both room and high temperatures.