Magnetic properties of iron-based soft magnetic composite improved by flexible ceramic powder at high frequency of MHz

FeSiAl/amorphous FeSiBCr soft magnetic composites (SMCs) and their low-pressure molded annular magnetic samples were prepared using the epoxy resin as binder and the flexible talcum powder as additive. The mechanism that talcum powder improved soft magnetic properties was systematically investigated by observing the microstructure and measuring the density, magnetic permeability, resistivity and magnetic loss. The results indicate that all the samples exhibit high insulation resistivity (in the range of 10 6 –10 7 Ω·m) and effective permeability (22.3-22.8, 1000 kHz). At the same frequency range (100-2000 kHz), the core losses firstly decrease and then increase with increasing talcum contents. Adding 1 wt.% talcum powder benefits achieving the lowest losses with the values of 873.5 kW/m 3 (1000 kHz, 20 mT) and 2395 kW/m 3 (2000 kHz, 20 mT) respectively, decreasing by 11.2 % and 12.2 % compared with the talc-free sample. The mechanism that the talcum powder addition reduces the loss is discussed according to the loss separation results.