PRODUCTION OF SEPARATING AGENT FOR ANNEALING FOR GRAIN ORIENTED SILICON STEEL SHEET

摘要

PURPOSE:To uniformly for a forsterite insulating film having excellent adhesiveness by annealing on the surface of a grain oriented silicon steel sheet subjected to decarburization annealing by coating MgO powder obtd. by calcining Mg(OH)2 at a specific temp. as a separating agent for annealing on the surface thereof. CONSTITUTION:The Mg(OH)2 obtd. by bringing the bittern and milk of lime as a by-product of salt manufacture into reaction is calcined in a rotary kiln, etc., to obtain the primary MgO having 70-200sec final reactivity 40% value of citric acid activity. The hexagonal planar Mg(OH)2 obtd. by the hydration reaction of such MgO is filtered and dried. The dried Mg(OH)2 is calcined in a 700-1,100 deg.C range to manufacture the MgO as the separating agent for annealing. Such separating agent is coated on the surface of the silicon steel sheet contg. a slight amt. of SiO2 after decarburization annealing and is annealed. The forsterite insulating film having the excellent adhesiveness is uniformly formed on the surface of the grain oriented silicon steel sheet.