Effect of sintering temperature on microstructure and magnetic properties for Fe-Si soft magnetic composites prepared by water oxidation combined with spark plasma sintering

Fe-Si SMCs with different insulating layer (Fe2SiO4/SiO2) have been prepared successfully via sintering the oxidized Fe-Si powders at different temperature. We have investigated the effect of sintering temperature on microstructure and magnetic properties for the Fe-Si SMCs in detail. The insulating layer is mainly Fe2SiO4 when the sintering temperature is 800 degrees C and 900 degrees C. Noting that a three-shell insulating layer composed of Fe2SiO4 and SiO2 is formed when the sintering temperature reaches 1000 degrees C. However, excessive sintering temperature including 1100 degrees C and 1200 degrees C, will result in the generation of SiO2 and many Fe atoms. Thus, the core loss and quality factor increase with increasing the sintering temperature from 800 degrees C to 1200 degrees C except for 1000 degrees C due to the unique three-shell insulating layer, while the saturation magnetization increases gradually. And optimized magnetic properties including very low core loss of 169.7 mW/cm(3), Ms of 183.6 emu/g,mu(e). of 59 and Q of 6.9 have been obtained for the Fe-Si SMCs sintered at 1000 degrees C.