High-permeability Fe-based soft magnetic composite comprising anisotropic Fe-Si chip fillers

Here, we demonstrate a novel hybrid soft magnetic composite (SMC) comprising highly-ductile pure-Fe powders and anisotropic Fe-6.5wt%Si chips to capture both high density and soft magnetic properties including high permeability and low core loss. Thin Fe-6.5wt%Si chips with dimensions of 2 mm x 0.5 mm x 0.04 mm were continuously fabricated through melt spinning using grooved copper wheels, and uniform and dense SiO2 surface insulation coatings on the Fe powders and Fe-Si chips were achieved through solution-based sol-gel process. Then, the hybrid SMCs were fabricated through compaction molding of pure Fe powder and Fe-Si mixtures with various mixing ratios. Degree of alignment of Fe-Si chips and packing density of the hybrid SMCs depending on powder-to-chip mixing ratio were systematically investigated, and their effects on the soft magnetic properties were thoroughly evaluated. Finally, the hybrid SMC with optimum powder-to-chip mixing ratio of 6:4 showed highest permeability of 472 and core loss of 157.34 W/kg (at 1 T and 1 kHz), which are 22.25% higher, and 51.05% lower values than those of pure-Fe SMC, confirming the effectiveness of Fe-Si chip fillers in the enhancement of soft magnetic properties of SMCs.