Highly improved middle to higher frequency magnetic performance of Fe-based soft magnetic composites with insulating Co2Z hexaferrites

Abstract Single-phase Co2Z hexaferrite with excellent middle to higher frequency performance was synthesized via the sol–gel method, and then were mechanically mixed with Fe powders and compacted to form toroidal Co2Z hexaferrites/Fe soft magnetic composites (Co2Z/Fe SMCs). After characterization with XRD, SEM, EDS, VSM and B-H Analyzer, the influence of Co2Z hexaferrites on the microstructures, AC and DC magnetic performance were investigated in detail. Air gaps between Fe powders are filled with Co2Z hexaferrites at the optimized content and the density of Co2Z/Fe SMCs increases. Co2Z hexaferrites effectively improve the soft magnetic performance of Co2Z/Fe SMCs at middle to higher frequency. The permeability and DC bias performance of Co2Z/Fe SMCs increased with the Co2Z hexaferrites content up to the maximum for 1 wt% Co2Z/Fe SMCs, and then decreased. While the changing trend of the core loss is opposite to the permeability and reaches the minimum for 1 wt% Co2Z/Fe SMCs. Co2Z hexaferrites not only increase the resistance of Co2Z/Fe SMCs and reduce the eddy-current loss, but also improve the interface microstructures and optimize the magnetic circuit of Co2Z/Fe SMCs.