High performance of Fe-based soft magnetic composites coated with novel nano-CaCO3/epoxy nanocomposites insulating layer

In this paper, a novel type of nano-CaCO3/epoxy nanocomposites insulating layer for the FeSiCr/carbonyl-iron soft magnetic composites (SMCs) has been successfully developed. The novel inorganic/resin nanocomposites can greatly reduce the core loss of the SMCs while maintain other excellent magnetic properties. By optimizing the content of insulating layer, the FeSiCr/carbonyl-iron SMCs exhibits the lowest core loss of 466.5 ​mW/cm3 at a maximum magnetic induction of 50 ​mT and frequency of 100 ​kHz, which is greatly reduced by 24.2%, compared with the sample only coated by epoxy resin. Meanwhile, the effective permeability and quality factor remains high. In addition, the production process of the novel nano-CaCO3/epoxy nanocomposites insulating layer exhibits the advantages of simplicity, convenience and low cost compared with other ceramic coatings (Al2O3, MgO, SiO2, etc.) and surface nitride coatings, which is more suitable for the industrialization of molded inductors, and therefore has a variety of industrial application prospects. A novel nano-CaCO3/epoxy nanocomposites insulating layer was successfully formed on the surface of FeSiCr/carbonyl-iron magnetic powders by surface modification method, which improved the resistivity of the insulation layer, reduced the core loss of soft magnetic composites, and improved the DC-bias performance. [Display omitted] •EDS mapping confirmed that the composite powders were coated with nano-CaCO3/epoxy nanocomposites insulating coating layer.•The high-resistivity of nanocomposites insulating layer are beneficial for the reduction of Pcv.•T1.0 possessed optimum Pcv ​= ​466.5 ​mW/cm3 (at 50 ​mT, 100 ​kHz, and 25 ​°C).