| 摘要 |
PURPOSE:To form insulating film excellent in heat resistance on the surface of an electrical sheet, by forming iron oxide film on the surface of the electrical sheet during continuous annealing, then by painting rust preventive oil suspended with inorg. material on the film so as to form inorg. coating. CONSTITUTION:On the surface of an electrical sheet which is used for iron core, such as silicon steel plate, pure iron base low carbon steel plate, is formed electrical insulating film in order to prevent the occurrence of eddy current during use. For that purpose, in continuous annealing of the electrical sheet at a temp. 700-850 deg.C for 0.2-3min, 0.03-0.1% oxygen or a suitable amount of water is added to the annealing atmosphere or to the atmosphere of cooling after annealing to form iron oxide film 0.05-0.2mum in thickness on the surface of the iron plate. The electrical sheet is painted with rust preventive oil suspended with inorg. compound such as talc, bentonite, thereby forming inorg. film together with the oxide film 0.15- 0.2mum in thickness. Hereby an electric sheet having insulating film excellent in heat resistance is manufactured. |
