Patent ID: 6713187
Filing Date: 2004-03-30
Classification: C21D,C23C,H01F,Y10T

Abstract:
A grain-oriented silicon steel sheet excellent in adhesiveness to tension-creating insulating coating films formed on the grain-oriented silicon steel sheet produced by removing inorganic mineral coating films composed of forsterite and so on with pickling or the like or by deliberately preventing the formation thereof, characterized by: having, at the interface between each of the tension-creating insulating coating films and the steel sheet, an external oxidation type membranous oxide film of 2 to 500 nm in average thickness mainly composed of amorphous silica and/or a mixed oxide film consisting of external oxidation type membranous oxide film of 2 to 500 nm in average thickness mainly composed of amorphous silica and particulate oxides mainly composed of amorphous silica: and satisfying any one or more of the following requirements A to E;A. that the percentage of said particulate oxides to said membranous oxide film is 2% or more in terms of area percentage at a cross-section; B. that the percentage of oxides composed of one or more elements selected from among Fe, Al, Ti, Mn and Cr in said membranous oxide film is 50% or less in terms of area percentage at a cross-section; C. that the percentage of voids in said membranous oxide film is 30% or less in terms of area percentage at a cross-section; D. that the percentage of metallic iron in said membranous oxide film is 30% or less in terms of area percentage at a section; and E. that the average thickness of low-density layers is 30% or less of the total thickness of said membranous oxide film when they are evaluated in terms of the ratio between elastic scattering strength and inelastic scattering strength measured by electron energy loss spectroscopy.