PURPOSE: To uniformly form a satisfactory insulating coating film by coating and baking without deteriorating iron loss characteristics by forming a coating film of a metal oxide, etc., on the surface of a grain-oriented silicon steel sheet after finish annealing and by brushing the formed film.
CONSTITUTION: The surface of a grain-oriented silicon steel sheet after finish annealing is smoothened by polishing and a coating film of the oxide, nitride, carbide, carbonitride, etc., of a metal is formed by CVD or PVD to reduce the iron loss of the steel sheet. The formed film is brushed and then an insulating coating film is formed by coating and baking. The brushing is preferably carried out in an aq. slurry of a salt of an alkali metal or alkaline earth metal.
SUZUKI KAZUHIRO
IGUCHI MASAO
