Novel NiZn-Ferrite Powders and Coatings for Electromagnetic Applications

This paper reports on the development of NiZn-ferrite powders and their deposition by air plasma and high-velocity oxyfuel spraying. The microstructure and phase composition of the powders and coatings are analyzed and the influence of process parameters on coating development is assessed for sprayed layers up to 500 μm thick. Particular attention is paid to the degradation of the spinel crystal structure, the formation of iron oxide phases, and elemental loss during spraying. The results show that a degree of ferrite decomposition occurs with the loss of zinc and formation of wüstite and that zinc loss is very dependent on the surface-to-volume ratio of the powder.