Microstructure and Magnetic Properties of Grain Boundary Insulated Fe/Mn0.5Zn0.5Fe2O4 Soft Magnetic Composites

Mn0.5Zn0.5Fe2O4 nano-powder was coated on Fe microparticles by mechanical ball milling combined with high-temperature annealing. The effects of milling time on the particle size, phase structure and magnetic properties of core-shell powder were studied. Scanning electron microscopy (SEM), energy-dispersive spectroscopy and X-ray diffraction showed that the surface of the milled composite powder was composed of thin layers of uniform Mn0.5Zn0.5Fe2O4 insulating powder. SEM also revealed a cell structure of Fe particles, indicating that the Fe particles were well separated and isolated by the thin Mn0.5Zn0.5Fe2O4 layers. Then, Fe/Mn0.5Zn0.5Fe2O4 soft magnetic composites were prepared by spark plasma sintering. The amplitude permeability of Fe/Mn0.5Zn0.5Fe2O4 SMCs in the Fe/Mn0.5Zn0.5Fe2O4 soft magnetic composites was stable. The resistivity decreased with the increase in sintering temperature. The loss of the composite core was obviously less than that of the iron powder core. Hence, the preparation method of Mn0.5Zn0.5Fe2O4 insulating iron powder is promising for reducing core loss and improving the magnetic properties of soft magnetic composites.

Automated summary

Mn0.5Zn0.5Fe2O4 nano-powder was successfully coated on Fe microparticles using mechanical ball milling combined with high-temperature annealing, resulting in the preparation of Fe/Mn0.5Zn0.5Fe2O4 soft magnetic composites. The study found that the thin Mn0.5Zn0.5Fe2O4 layers effectively isolated the Fe particles, reducing loss and improving magnetic properties.