Influence of the Resin Content on the Dynamic Energy Losses in Iron–Phenolphormaldehyde Resin Composites

Frequency dependence of energy losses of iron-phenolphormaldehyde resin composite materials in relation to the movability of domain walls during the magnetization process has been studied. The usual three-component concept of separation of total losses has been proposed for the case of magnetic composites by introducing simplifications in the classical losses calculation and pointing out the different frequency dependence of excess losses (also called anomalous) in comparison with homogeneous materials, which was explained by the different frequency dependences of a number of movable domain walls. Experimental results on samples with different resin contents confirmed the explanation and revealed the influence of inner demagnetizing fields on the activation of domain walls, which led to the fact that increasing the amount of resin does not minimize the dynamic losses.