High resistivity and low core loss of intergranular insulated Fe–6.5 wt.%Si/SiO2 composite compacts

Abstract

Intergranular insulated Fe–6.5wt.%Si/SiO2 composite compacts were prepared by in-situ chemical deposition combined with a subsequent spark plasma sintering process. Most of the conductive Fe–6.5wt.%Si alloy particles were coated with SiO2 insulating layer in Fe–6.5wt.%Si/SiO2 composite compacts. The presence of SiO2 insulating layer increased the resistivity by two orders of magnitude for intergranular insulated Fe–6.5wt.%Si/SiO2 composite compacts (4.8×10−5Ω·m) compared with that of Fe–6.5wt.%Si compacts without SiO2 insulating layer (9.7×10−7Ω·m). In addition, most of the eddy currents could be confined in the SiO2-coated Fe–6.5wt.%Si particles, which equated to reducing the effective radius of eddy current in Fe–6.5wt.%Si alloy. So, the intergranular insulated Fe–6.5wt.%Si/SiO2 composite compacts presented a lower core loss compared with that of Fe–6.5wt.%Si compacts without SiO2 insulating layer or traditional Fe–6.5wt.%Si electrical steels at medium and high frequencies. Good soft magnetic properties were also obtained for the intergranular insulated Fe–6.5wt.%Si/SiO2 composite compacts, with a saturation magnetization of 164.6emu/g, a coercive force of 12Oe, and a relative permeability of 3.2×103 at 50Hz. The intergranular insulated Fe–6.5wt.%Si/SiO2 composite compacts provide valuable inspiration for developing new high silicon electrical steel cores with low core loss and excellent magnetic and electric properties.