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

Intergranular insulated Fe–6.5   wt.%Si/SiO 2 composite compacts were prepared by in-situ chemical deposition combined with a subsequent spark plasma sintering process. Most of the conductive Fe–6.5   wt.%Si alloy particles were coated with SiO 2 insulating layer in Fe–6.5   wt.%Si/SiO 2 composite compacts. The presence of SiO 2 insulating layer increased the resistivity by two orders of magnitude for intergranular insulated Fe–6.5   wt.%Si/SiO 2 composite compacts (4.8   ×   10 −   5   Ω·m) compared with that of Fe–6.5   wt.%Si compacts without SiO 2 insulating layer (9.7   ×   10 −   7   Ω·m). In addition, most of the eddy currents could be confined in the SiO 2 -coated Fe–6.5   wt.%Si particles, which equated to reducing the effective radius of eddy current in Fe–6.5   wt.%Si alloy. So, the intergranular insulated Fe–6.5   wt.%Si/SiO 2 composite compacts presented a lower core loss compared with that of Fe–6.5   wt.%Si compacts without SiO 2 insulating layer or traditional Fe–6.5   wt.%Si electrical steels at medium and high frequencies. Good soft magnetic properties were also obtained for the intergranular insulated Fe–6.5   wt.%Si/SiO 2 composite compacts, with a saturation magnetization of 164.6   emu/g, a coercive force of 12   Oe, and a relative permeability of 3.2   ×   10 3 at 50   Hz. The intergranular insulated Fe–6.5   wt.%Si/SiO 2 composite compacts provide valuable inspiration for developing new high silicon electrical steel cores with low core loss and excellent magnetic and electric properties.