Microwave induced in-situ formation of SiC nanowires on SiCNO ceramic aerogels with excellent electromagnetic wave absorption performance

Electromagnetic absorption (EMA) materials with light weight and harsh environmental robustness are highly desired and crucially important in the stealth of high-speed vehicles. However, meeting these two requirements is always a great challenge, which excluded the most attractive lightweight candidates, such as carbon-based materials. In this study, SiC_nw-reinforced SiCNO (SiC_nw/ SiCNO) composite aerogels were fabricated through the in-situ growth of SiC_nw in polymer-derived SiCNO ceramic aerogels by using catalyst-assisted microwave heating at ultra-low temperature and in short time. The phase composition, microstructure, and EMA property of the SiC_nw/SiCNO composite aerogels were systematically investigated. The results indicated that the morphology and phase composition of SiC_nw/SiCNO composite aerogels can be regulated easily by varying the microwave treatment temperature. The composite aerogels show excellent EMA property with minimum reflection loss of -23.9 dB@13.8 GHz, -26.5 dB@10.9 GHz, and -20.4 dB@14.5 GHz and the corresponding effective bandwidth of 5.2 GHz, 3.2 GHz, and 4.8 GHz at 2.0 mm thickness for microwave treatment at 600 ℃, 800 ℃, and 1000 ℃, respectively, which is much better than that of SiCN ceramic aerogels. The superior EMA performance is mainly attributed to the improved impedance matching, multi- reflection, multi-interfacial polarization, and micro current caused by migration of hopping electrons.