Preparation and magnetic properties of core–shell structured Fe-Si/Fe3O4 composites via in-situ reaction method

Abstract The Fe-Si/Fe3O4 soft magnetic composites (SMCs) have been fabricated via in-situ reaction method. A layer of Fe3O4 was formed on the Fe-Si particles in the KNO3 solution, and the growth mechanism of the Fe3O4 coating layer has been studied, and its formation and thickness can be controlled by adjusting the concentration of KNO3 solution to obtain the microstructure of the composites and then adjust the magnetic performance of SMCs. The formation of Fe3O4 shell on Fe-Si particles can effectively reduce the core loss of the composites. The samples in-situ reacted in 0.1 mol/L KNO3 solution exhibit excellent comprehensive properties with high saturation magnetization, relatively high permeability (34), great frequency stability of permeability, and very low core loss of 13.6 w/kg (measured at 20 mT and 150 kHz).