Excellent electrically insulated, thermal-oxidation resistant and corrosion resistant flaky-FeSiAl/BN core–shell composites for high-performance microwave absorption in harsh environments

Currently, multifunctional microwave absorption (MA) materials have become increasingly important in addressing the serious issue of electromagnetic pollution. In this study, flaky FeSiAl (FFSA)/hexagonal boron nitride (h-BN) composites with a core–shell structure were prepared by plasma-assisted ball milling. The FFSA9BN1 composite, with a mass ratio of 9:1 (FFSA:h-BN), exhibits a minimum reflection loss (RLmin) of −68.18 dB at a thickness of 2.14 mm, because the h-BN shells improve the impedance matching of the composites and produce abundant polarization loss. Additionally, the MA performance of the composites hardly shows a decline even after a thermal oxidation at 500 °C for 12 h due to the dense h-BN shells as oxygen barriers. Simultaneously, the corrosion rate of the FFSA/h-BN composites is 66.5% less than that of the FeSiAl cores. Consequently, plasma-assisted ball milling provides a facile and eco-friendly technology to prepare multifunctional FFSA/h-BN core–shell composites for diverse applications in some extreme environments.