An excellent soft magnetic Fe/Fe₃O₄-FeSiAl composite with high permeability and low core loss

It is well know that the high temperature annealing can improve the permeability and reduce the hysteresis loss of soft magnetic composites (SMCs), but the eddy current loss would be accordingly increased. Thus, developing SMCs with high permeability and low core loss remains a challenge. Herein, we prepared a kind of Fe/Fe₃O₄-FeSiAl soft magnetic composites by replacing some Fe powders with FeSiAl, possessing high permeability and low core loss. In the fabricating process, reduced iron powders were coated with a Fe_xO_y insulating layer by surface oxidation method and the Fe/Fe_xO_y and FeSiAl alloy powders were used as raw materials to fabricate Fe/Fe_xO_y and Fe/Fe_xO_y-FeSiAl SMCs. Moreover, the optimum content of FeSiAl powders and the effects of high temperature annealing on the structure and performance of Fe/Fe_xO_y and Fe/Fe_xO_y-FeSiAl SMCs was investigated. These results of XRD, XPS and FTIR showed the Fe₂O₃ and Fe-OH existing in the Fe_xO_y insulating coating is gradually transformed to Fe₃O₄ under annealed at 550 ℃, and the permeability and eddy current loss were greatly increased for Fe/Fe_xO_y SMCs. However, the permeability was highly increased but the eddy current loss stay unchangeable for Fe/Fe_xO_y-FeSiAl SMCs. These results strongly demonstrated the Fe/Fe₃O₄-FeSiAl SMCs have high permeability and low core loss.