Scalable preparation of SiC@SiO2 nanocable aerogels for broadband microwave absorption using low-cost carbon source

Abstract

Despite significant efforts, microwave contamination has become increasingly common and difficult to address. Given this complication, SiC nanowire aerogels emerge as promising candidates for microwave absorbers due to their hybridized ceramic-electromagnetic properties, ultra-low density, and high porosity. However, conventional methods for preparing SiC nanowires heavily rely on reaction equipment and protective gases, as well as expensive or toxic raw materials. Therefore, we present a facile, catalyst-free, and cost-effective method for synthesizing ultralight and elastic SiC@SiO2 nanocable aerogels (SNCA) using a low-cost carbon source. With a unique three-dimensional assembly structure, the as-prepared SNCA exhibits a significant compressive-recovered property, which is rare in ceramic materials. Moreover, the optimized SNCA demonstrates a wide effective absorption bandwidth (10.2 GHz) and strong reflection loss (−56.6 dB) for microwave absorption applications, with the attenuation mechanism primarily attributed to multiple reflections, interface polarization, and dipole polarization. These findings suggest that SiC nanofiber aerogels synthesized using this low-cost general method hold immense potential for next-generation microwave absorbing devices in extreme environments.