METHOD FOR FORMING FILM CONTAINING ZIRCONIA ON SURFACE OF SILICON STEEL SHEET

摘要

PURPOSE:To form an insulating film having an excellent magnetic characteristic on the surface of a silicon steel sheet by performing electrolysis with the silicon steel sheet as a cathode in an aq. soln. contg. a Zr complex compd. to deposit a Zr compd. and further coating MgO thereon and drying the same then annealing the steel sheet. CONSTITUTION:A silicon steel material contg. about 2-4% Si is made into an about 0.2-0.35mm. thick sheet by hot rolling-annealing of the hot rolled sheet- pickling-cold rolling and the sheet is subjected to decarburization annealing at about 200-300 deg.C then to drying. Such silicon steel sheet as a cathode is electrolyzed in an aq. soln. contg. a Zr complex compd. (for example, hexafluorozirconium ammonium) to deposit a Zr-contg. compd. on the surface of the silicon steel sheet. MgO is further coated thereon and is dried and thereafter the steel sheet is annealed to form an insulating film having an excellent magnetic characteristic thereon. Such silicon steel sheet is subjected to secondary recrystallization by high temp. annealing to about 1,200 deg.C in a gaseous mixture composed of H2 and H2 then the atmosphere is exchanged with 100% H2 atmosphere to remove impurities. The grain-oriented silicon steel sheet is thus obtd.