Preparation and characterization of iron-based soft magnetic composites with resin bonded nano-ferrite insulation

Soft magnetic composites consisting of Fe powder insulated by Ni-Zn/Cu-Zn ferrite nanoparticles bonded by boron modified phenolic resin with different resin-to-ferrite ratios and iron volume contents were prepared. The structure of composites was documented and the magnetic, electrical and mechanical properties were analysed and compared with the reference iron-resin samples. The significantly improved magnetic properties were found, indicating the involvement of the ferrite in magnetization process, maintaining the continuity of magnetic flux through composite material by interaction with iron particles and reduction of inner demagnetizing fields. The increased total, differential and irreversible permeability, the slightly decreased coercivity and total power losses and the sufficiently high electrical resistivity reflected by relatively high DC bias stability and high frequency stability of real part of complex permeability, together with its relatively high initial value give evidence that the resin-ferrite mixture (1/2:1/2) serve as optimal magnetically active insulation coating of iron particles. (C) 2020 Elsevier B.V. All rights reserved.