NiZnCu-ferrite coated iron powder for soft magnetic composite applications

Soft magnetic composites (SMCs) comprised of ferrimagnetic and electrically insulating coating materials for iron powder are capable of increasing frequency ranges and efficiency of electromagnetic devices, nominally electric motors. Soft ferrites can withstand stress relieving temperatures and allow for reduction in eddy current contributions while minimally effecting magnetic performance. This work demonstrates the effectiveness of a NiZnCu-ferrite coating material of 5 wt%, 10 wt%, and 15 wt% on iron powder using traditional press and cure (700 °C) powder metallurgy techniques. Powder properties such as apparent density and Hall flow rate are used to determine effect of acoustic mixing procedure on coating uniformity. An increase in resistance and porosity are found for increasing coating amount, with subsequent decreases in density, permeability, and magnetic saturation. We find lower core loss values for increasing coating amount, related to eddy current loss, however, lower induction levels are also seen. Our work highlights the importance of soft ferrites, more specifically Ni0.5Zn0.3Cu0.2Fe2O4, and their ability to vastly improve SMC developments using more traditional powder metallurgy (PM) techniques.