Study on novel Fe-based core-shell structured soft magnetic composites with remarkable magnetic enhancement by in-situ coating nano-ZnFe2O4 layer

Soft magnetic composites based on spherical supersendust (Fe85Si8Al4Ni3) powder were made by gas atomization. The nano-ZnFe2O4 layer was coated on the surface of Fe85Si8Al4Ni3 powder particles by in-situ oxidation. Core-shell structured microspheres were achieved and then mixed with epoxy-modified silicone resin. Lorentztransmission electron microscopy confirmed the core-shell structure of the Fe85Si8Al4Ni3-ZnFe2O4 microspheres. The uniform surface layer consisted of nano-ZnFe2O4 layer was clarified by scanning electron microscopy and energy dispersive spectroscopy X-ray analysis. The ferromagnetic nano-ZnFe(2)O(4 )layer effectively reduces magnetic dilution, while high electrical resistivity of both ZnFe2O4 and ESP provides satisfactory insulation of the SMCs, giving rise to simultaneous high permeability and extraordinary low core loss. Magnetic properties were determined using a vibrating sample magnetometer and an auto testing system for magnetic materials (SY8258B-H/m). The results show that the samples prepared at 1200 MPa and 550 degrees C exhibited distinguished magnetic properties, with core loss of 89 W/kg (100 kHz, 50 mT) and amplitude permeability of 50 whose frequency stability is up to 170 kHz. The Fe85Si8Al4Ni3SMCs with excellent soft magnetic properties provide great potential for application of various fields such as transformers, sensors and electromagnetic actuation devices. Our approach can be expanded to other Fe-based SMCs.