Magnetic properties of surface-treated Fe-Si-B amorphous alloy

Magnetic properties of Fe-B-Si amorphous alloy with four kinds of coating were studied in straight ribbons and toroidal core. The results have shown that 1) Coating increases hysteresis loss with its thickness and reduces frequency dependent loss. 2) Coating introduces fine magnetic domains perpendicular to main domains induced by field-annealing in N2. These fine domains about 0.01 ∼0.03mm wide, appear when stress by casting is relieved, and they are very stable in magnetization. 3) Interlaminar insulation by coating has effect on eddy current loss in cores when surface pressure is increased. 4) Among inorganic coatings, Al2O3coating by anodic deposition process, shows low deterioration of loss in high insulation resistivity.