The effect of coatings on the stress dependent magnetic properties of oriented silicon steel

The effect of laboratory applied mill-glass and high stress secondary coatings on the magnetic properties of oriented 3% Si Fe was determined by examining the dependence of the core losses and exciting characteristics on uniaxial stress. The results indicate that bare specimens required the least compressive stress to cause an increase in losses. Mill-glass and secondary coated specimens could withstand larger compressive stress before the losses are degraded. For quantitative analysis, a loss-degradation stress parameter (σ.1) was defined. Typical values of (σ.1) for bare, mill-glass, and secondary coated specimens were 0.66, 2.58 and up to 4.94 MPa respectively. It is shown that the (σ.1) values increase linearly with applied secondary coating weight. The (σ.1) values are apparently related to the residual or coating induced stress in the specimen. It was noted that the minimum in the exciting characteristics occurred at a compressive stress close to the (σ.1) value.