Enhanced magnetic properties and reduced core loss of intergranular insulating Fe-Si soft magnetic composites with three-shell SiO2-Fe2SiO4-SiO2 insulating layer

摘要

The intergranular insulating Fe-Si soft magnetic composites (SMCs) with uniform three-shell SiO2-Fe2SiO4-SiO2 insulating layer were prepared successfully via simple water oxidation combined with the spark plasma sintering process (SPS). The formation mechanism of the insulating layer and the magnetic properties of the Fe-Si SMCs have been studied systematically. Note that the simple water oxidation process could well ensure the uniformity of the oxide layer consisting of Si and Fe3O4. And then, the high temperature solid-state reactions during the SPS process would result in the conversion of the oxide layer (Si-Fe3O4) to the insulating layer with special three-shell structure (SiO2-Fe2SiO4-SiO2). As a consequent, the Fe-Si SMCs exhibit excellent performance suah as high saturation magnetization (181.9 emu/g), stable effective permeability (60.5) and very low core loss (7.8 W/kg at 50 kHz). The results indicate that the preparation method in this study is simple and effective to produce high performance Fe-Si SMCs used in the field of electromagnetic conversion equipment.