Eco-friendly soft magnetic composites of iron coated by sintered ferrite via mechanofusion

The paper presents novel soft magnetic composite materials composed of iron coated by Ni-Zn/Cu-Zn soft ferrite powder using dry particle coating route, without any other non-magnetic insulation. High-pressure compaction was applied to achieve relatively low porosity and sufficiently high density of composites. Structure documentation indicated optimal insulation of iron particles by the ferrite, which was confirmed by magnetic, electrical and thermal properties evaluation. Relatively high frequency and DC bias stability of the permeability was found together with its relatively high values, as the ferrite was involved in magnetization process improving magnetic flux continuity. Sufficiently high specific electrical resistivity ensured also relatively low power losses at elevated frequencies. Proportions of reversible and irreversible magnetization processes were analysed by means of high and low induction loss separation and differential, reversible and irreversible permeability measurement. The investigation of thermal diffusivity revealed the heat transfer rate capability of composites and also confirmed good insulation of iron by ferrite powder. The properties were reached better compared to the ones of iron-based composites with non-magnetic matrix and competitive with those found in current literature, indicating the successful preparation of pure iron-ferrite composites by means of the use of progressive eco-friendly and costeffective production techniques.