Fe–6.5% Si/SiO2 powder cores prepared by spark plasma sintering: Magnetic properties and sintering mechanism

Abstract

The Fe–6.5% Si/SiO2 powder cores were prepared by dry-type stirring ball milling and subsequent spark plasma sintering (SPS). Microstructure, magnetic properties and sintering mechanism of Fe–6.5% Si/SiO2 powder core were investigated. The experimental result indicated that Fe–6.5% Si particles were perfectly surrounded by SiO2 insulating layer with cristobalite structure. Compared with Fe–6.5% Si powder core, Fe–6.5% Si/SiO2 powder core has 20 times higher electrical resistivity ([Formula: see text]) and maintained excellent soft magnetic properties ([Formula: see text] emu/g, [Formula: see text] Oe). Core losses decreased to nearly 1/10 of those of Fe–6.5% Si powder core due to the insulation effect of SiO2 particles. Sintering mechanisms of Fe–6.5% Si/SiO2 core-shell powders during spark plasma sintering are proposed on the basis of high electrical resistivity (easy to heat) and pin effects (easy to discharge) of SiO2 particles.