Preparation and Characterization of MnFe2O4/Fe Soft Magnetic Composites by Surface Oxidation

MnFe2O4/Fe soft magnetic composites (SMCs) were designed by the surface oxidation method, and the MnFe2O4 layer was utilized as the insulation coating. The microstructure of SMCs and the chemical composition of the insulation layer were observed using scanning electron microscopy and energy-dispersive spectroscopy. The surface phase composition of SMCs was characterized using X-ray diffraction, X-ray photoelectron spectrometry, and Raman spectroscopy. The effect of annealing temperature on the insulation layer was investigated, and its relationship with the magnetic properties of the MnFe2O4/Fe SMCs was explored. The best overall performances were obtained at 50 mT and 100 kHz with saturation magnetization Ms = 205 emu/g, amplitude permeability μa = 100, and a core loss of 234.9 W/kg. Therefore, this work can provide a method to develop a novel insulating coating to reduce core loss, which is of great significance to the investigation of other Fe-based soft magnetic composites for applications in high-frequency magnetic fields.