INSULATING FILM TREATMENT AGENT, GRAIN-ORIENTED ELECTRICAL STEEL SHEET COATED WITH THE FILM TREATMENT AGENT AND INSULATING FILM TREATMENT METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To improve the magnetic properties of a grain-oriented electrical steel sheet free from chromic acid by increasing tensile strength of an electrical insulating film of the grain-oriented electrical steel sheet higher than before.;SOLUTION: An insulating film treatment agent contains a phosphate and colloidal silica as principal elements, wherein the ratio of the colloidal silica to 100 pts.wt. of the phosphate is 30 to 70 pts.wt. and in metal components in the phosphate, the content of bivalent metallic elements is 20 to 80 wt.%, the content of trivalent metals is 10 to 70 wt.% and the content of metallic elements having 4 or more valences is 3 to 20 wt.%. The grain-oriented electrical steel sheet has a high tensile strength insulating film with a composition obtained by applying the above treatment liquid onto the surface of the steel sheet and baking the liquid.;COPYRIGHT: (C)2010,JPO&INPIT