The effect of forsterite coatings on magnetic properties and domain structure of grain oriented 3% Si–Fe

Abstract

Magnetic properties and domain structures were obtained on commercial grain oriented 3% Si–Fe before, during, and after removal of the forsterite base coating. A 200 kV Scanning Electron Microscope (SEM) was used for static and dynamic domain observations. Magnetic properties were correlated to the observed domain structure. Forsterite coatings significantly reduce both 180° domain wall spacings and the density of supplementary flux closure domains. However, lower losses were not realized from such alterations of the domain structures. The increased core losses can be rationalized in terms of the behavior of the domain structure during cyclic magnetization. The formation of the forsterite base coating leads to nonuniform, irreproducible 180° domain wall movement and pinning of the domain walls at subsurface forsterite particles.