Performance improvement of Fe−6.5Si soft magnetic composites with hybrid phosphate-silica insulation coatings

Fe−6.5Si soft magnetic composites (SMCs) with hybrid phosphate-silica insulation coatings have been designed to improve their comprehensive property via chemical coating combining sol-gel method in this work. The microstructure and magnetic performance of the Fe−6.5Si SMCs with hybrid phosphate-silica insulation coatings were investigated. The hybrid phosphate-silica coatings with high heat resistance and high withstand pressure, formed on the surface of the Fe−6.5Si ferromagnetic powders, were found stable in the composites. Compared with Fe−6.5Si SMCs coated by single phosphate or single silica, Fe−6.5Si SMCs with hybrid phosphate-silica show much higher permeability and lower core loss. The work provides a new way to optimize the magnetic performance of soft magnetic composites.