| 摘要 |
PURPOSE:To form the insulating films having high adhesion and the high tension to be imparted on a grain oriented electrical steel sheet by forming the films having the good adhesion to the steel sheet on the steel sheet, then applying insulation coatings of a colloidal silica-phosphate system thereon. CONSTITUTION:The insulating films having the high adhesion to the grain oriented electrical steel sheet are formed at <=4g/m<2> per one surface on the steel sheet. The insulation coatings consisting essentially of colloidal silica and phosphate are then applied thereon. Substrate films are formed by coating the steel sheet with an aq. primary phosphate soln. of >=1 kinds of Al, Mg, Sr, Ba and Fe or an aq. phosphoric acid soln. and baking the coatings at about >=350 deg.C. An aq. alkaline metal silicate soln. is also usable for forming the substrate films. The insulation coating liquid consists of (1) the colloidal silica, (2) >=1 kinds of the primary phosphate selected from Al, Mg, Sr, Ba and Fe and (3) >=1 kinds of chromic anhydride and chromates as basic components. |
