The effects of Fe nano-powders on compaction behaviors and magnetic properties of SMCs

Abstract

Currently, metallic soft magnetic composites, due to their high saturation magnetization, have attracted much attention for application in high frequency mobile devices. These composites must approach a full densification to achieve the high permeability and magnetic flux density necessary for mobile device applications. This study was carried out to investigate the effects of Fe nano-powders on the compaction behaviors and magnetic properties of Fe-Si alloy composites. Fe-Si micro-powders were fabricated using a gas-atomizer; then, SiO2 was coated on them to suppress eddy current loss. Fe-nano-powders were obtained using spray-dried Fe2O3 powders. These nano-powders were homogeneously mixed with Fe-Si micro-powders to increase the density of the compacts. As a result, the composite with 80 wt% micro-powders showed excellent high frequency properties due to high compaction density. Microstructural analysis shows that changes in the magnetic properties of the composites are dependent on the fill factor and electrical path-ways of non-insulated nano-powders in pores between insulated micro-powders.