Enhanced soft magnetic properties and high-frequency stability of FeNiMo powder cores by coating SiO(2) insulation layer

FeNiMo/SiO(2) powder cores were prepared using the sol–gel method. Tetraethyl orthosilicate (TEOS) was added to produce an amorphous SiO(2) coating outside the FeNiMo particles to form a core–shell structure. The thickness of the SiO(2) layer was designed by varying the concentration of TEOS, and the optimized permeability and magnetic loss of the powder core could achieve 78.15 and 633.44 kW m(−3) at 100 kHz and 100 mT, respectively. Compared with other soft magnetic composites, these FeNiMo/SiO(2) powder cores have a significantly higher effective permeability and a lower core loss. Surprisingly, the high-frequency stability of permeability could be substantially enhanced through the insulation coating process in which μ(f)/μ(100 kHz) could reach 98.7% at 1 MHz. In comparison with 60μ commercial products, the comprehensive soft magnetic properties of the FeNiMo/SiO(2) cores were superior to most manufacturers, which would be potentially applied to high-performance inductance devices in high-frequency ranges.