Quantitative analysis of factors increasing coercive field of iron powder cores – Influence of inclusions

Abstract

The quantitative contribution of inclusions to coercive field in iron powder cores with different amounts of Si oxide inclusions was separated from that of other microstructural factors and analyzed. Coercive field decreased by 2.8 A m−1 with a 0.01 mass% decrease in the amount of Si in oxide. Si oxide inclusions also affected the recovery and recrystallization of the α-Fe phase, and the contribution of crystal grain boundaries and the contribution of dislocations decreased with a decrease in the amount of Si in oxide. The contribution of inclusions was compared with Kersten's calculation model based on changes of the domain wall area and Neel's calculation model based on changes of the number of magnetic poles, and the observed value was closer to the results of Kersten's calculation model. This suggests that the contribution of magnetic poles generated around an inclusion is small and the change of the domain wall area around the inclusion makes a larger contribution to coercive field.