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/cm(3), at 100 kHz and 40 mT). And the influence of introduce of SiO2 particles on the microstructure and magnetic properties was discussed.