Ultra-Low Core Loss in Fesi Soft Magnetic Composites by Fe2o3 Nanoparticles Air Gap Filling

Abstract

Soft magnetic materials are crucial in motors, generators, transformers, and many electronic devices. We synthesized the FeSi soft magnetic composites (SMCs) with different doping contents of Fe2O3 nanopowders as fillers via the hot-press sintering technique. The soft magnetic properties and microstructure of Fe2O3 nanopowder-filled composites (0-5 wt%) in Fe-6.5 wt% Si SMCs reveal that Fe2O3 nanopowders effectively fill the air gaps between FeSi powders, increasing SMC density. Moreover, all samples exhibit excellent effective permeability stability across the 15 to 100 kHz frequency range. Notably, the effective permeability µe improves from 22.32 to 30.45, a 36.42% increase, when the Fe2O3 doping concentration increases from 0 to 2 wt.%. Adding Fe2O3 nanopowders enhances electrical resistivity, leading to a 37.21% reduction in eddy current loss in samples for 5 wt.% Fe2O3 addition, compared to undoped samples. Furthermore, as Fe2O3 content increases from 0 to 5 wt.%, the power loss Pcv of the Fe2O3-doped Fe-6.5Si SMCs decreases from 25.63 kW/m3 to 16.13 kW/m3, a 37% reduction. These results suggest that Fe2O3-doped FeSi SMCs, with their superior soft magnetic properties, hold significant potential for use in high-power and high-frequency electronic applications.

Keywords: soft magnetic composites (SMCs), Core loss, FeSi, Fe2O3 nanopowders, Permeability.