Effects of nano-SiO₂ on microstructure and magnetic properties of FeSi soft magnetic composites

FeSi soft magnetic composites (SMCs) were fabricated using nano-SiO₂/epoxy silicone resin (ESR) as insulating layers, and the influence of SiO₂ content on microstructure and magnetic properties of soft magnetic composites were investigated. The introduction of suitable nano-SiO₂ into epoxy silicone resin increase the density, permeability and resistivity which then reduce of magnetic loss of SMCs. SiO₂ nanoparticles distribute in the ESR and coat on the magnetic metal particle surface, and the formation of insulating coating caused by the addition of SiO₂ nano-particles reduce the magnetic loss and which can be attributed to the reduction of eddy-current loss. Excess SiO₂ addition result in the aggregation of SiO₂ particle between magnetic particles, which then destroy magnetic performance. The SMCs with 0.50 wt% SiO₂ has the optimized performance with high effective permeability (94) and reduced magnetic loss (152.03 mW/cm³, at 100 kHz and 40 mT). And the influence of introduce of SiO₂ particles on the microstructure and magnetic properties was discussed.