Ultrabroad electromagnetic absorbing core-shell SiC@SiO₂ nanocomposites derived from in situ oxidation SiC whiskers

The amazing developing electromagnetic technology has brought severe challenges to the military and civilian fields, efficient electromagnetic wave absorption (EWA) materials with high-temperature resistance are urgent needed. In this paper, SiC@SiO₂ nanocomposites with unique core-shell structures were successfully prepared using a straightforward method by in situ oxidation SiC whiskers. By regulating the sintering temperature and oxidation time, the microstructures and EWA performance of SiC@SiO₂ nanocomposites were explored. The results show that the core-shell SiC@SiO₂ nanocomposites obtained after sintering at 1200 ℃ for 0.5 h exhibits the best EWA performance, where the minimum reflection loss (RL_min) of −36.80 dB at the thickness of 2.68 mm and the effective absorption bandwidth (RL<-10 dB, EAB) of 9.85 GHz at a matching thickness of 4.24 mm. Specially, the EAB can reach up 10.98 GHz with the filling content of only 10%, which surpasses most SiC-based absorbers. The ultrabroad absorbing bandwidth can be attributed to that the unique core-shell structures of SiC whiskers with in-situ grown SiO₂ layers on the surface provide good impedance matching, multiple reflection and scattering and interface polarization effects. This work provides a new strategy for the design of high temperature resistant absorbing materials.