Preparation and magnetic properties of FeSiAl-based soft magnetic composites with MnO/Al2O3 insulation layer

Abstract In this paper, a novel core–shell structured FeSiAl@MnO/Al2O3 soft magnetic composites (SMCs) has been fabricated by the combination of ball milling with MnO2 and spark plasma sintering (SPS) process. The structure and phase evolution of MnO/Al2O3 insulation layer also were investigated. Meanwhile, the influences of various MnO2 content on magnetic properties of FeSiAl SMCs have been revealed. The results indicate that MnO/Al2O3 insulation layer with high resistivity (32.46 mΩ·cm) is conducive to the frequency stability of permeability. In particular, the total core loss of FeSiAl@MnO/Al2O3 SMCs is only 6.71 W/kg, which is 94.1% lower than that of original FeSiAl (113.6 W/kg) at 50 kHz. It implies that the novel core–shell structure is a powerful method to increase resistivity and reduce total core loss of SMCs, which can significantly improve energy utilization.