This grain-oriented electrical steel sheet has a base steel sheet in which a final-annealed film is substantially not present on a surface, an intermediate layer that is disposed on a surface of the base steel sheet and mainly contains silicon oxide, and an insulation coating disposed on a surface of the intermediate layer. In the intermediate layer, a value obtained by dividing a standard deviation σ of a thickness of the intermediate layer by an average value T of the thickness of the intermediate layer is 0.500 or less.

[Problem] To propose a stainless steel structure excellent in hydrogen embrittlement resistance and corrosion resistance, being high in mass productivity, simple in device structure, low in equipment cost, and having a high cost advantage, and a method for manufacturing the same.

[Solving means] It is stainless steel having hydrogen embrittlement resistance and corrosion resistance, a surface of electrolytically polished stainless steel being coated with a film obtained by passivating a metal oxide formed by a wet process, wherein the film thickness of the film obtained by passivating the metal oxide formed by a wet process is greater than 100 nm. A hydrogen permeability ratio (film-formed product/film-unformed product) is equal to or less than 2.0×10.sup.−2, and a relative reduction of area (under a hydrogen atmosphere of 110 MPa/under a nitrogen atmosphere of 10 MPa) in an SSRT test is equal to or greater than 0.8. It includes a polishing treatment step, a film-forming step, a curing treatment step, and a passivation treatment step, and the passivation treatment step consists of at least two or more independent passivation treatment steps.

In a base sheet for a grain-oriented electrical steel sheet of the present invention, an amount of surface oxygen x per one surface of the base sheet and a value y of a peak (ΔR/R.sub.0 @1250 cm.sup.−1) of SiO.sub.2 on the surface of the base sheet obtained by infrared reflection spectroscopy satisfy y≥1500x.sup.2.5 and y≥0.24. A method of manufacturing the base sheet for a grain-oriented electrical steel sheet of the present invention includes: adjusting the amount of surface oxygen per one surface of a final-annealed grain-oriented silicon steel sheet to more than 0.01 g/m.sup.2 and 0.05 g/m.sup.2 or less, or more than 0.05 g/m.sup.2 and 0.10 g/m.sup.2 or less; and performing thermal oxidation annealing in an atmosphere in which an oxidation potential represented by a ratio P.sub.H2O/P.sub.H2 of water vapor pressure to hydrogen pressure is 0.0081 or less in a case where the amount of surface oxygen is more than 0.01 g/m.sup.2 and 0.05 g/m.sup.2 or less, or in an atmosphere in which the oxidation potential is 0.005 or less in a case where the amount of surface oxygen is more than 0.05 g/m.sup.2 and 0.10 g/m.sup.2 or less, at a soaking temperature of 1000° C. or lower to form an externally oxidized layer on a surface of the grain-oriented silicon steel sheet.

The present invention provides an aqueous passivation composition for the treatment of zinc or zinc alloy coatings, comprising: i) phosphoric acid; ii) at least one water-soluble polyphosphonic acid or a water-soluble salt thereof, iii) at least one divalent metal cation (M.sup.2+); and, iv) at least one water-soluble or water-dispersible fluoroacid or a salt thereof, wherein said fluoroacid is defined by the following general empirical formula (II):

H.sub.pT.sub.qF.sub.rO.sub.s   (II)

wherein: each of q and r represents an integer from 1 to 10; each of p and s represents an integer from 0 to 10; and, T represents an element selected from the group consisting of Ti, Zr, Hf, Si, Sn, Al, Ge, and B.

Provided are an insulation-coated oriented magnetic steel sheet having an insulating coat with excellent heat resistance; and a method for manufacturing the same. This insulation-coated oriented magnetic steel sheet has an oriented magnetic steel sheet, and an insulating coat arranged on the surface of the oriented magnetic steel sheet, the insulating coat containing Si, P, O, and Cr, and at least one element selected from the group consisting of Mg, Ca, Ba, Sr, Zn, Al, and Mn. The XPS spectrum of the outermost surface of the insulating coat has peaks observed at Cr2p.sub.1/2 and Cr2p.sub.3/2.

Provided are an insulation-coated oriented magnetic steel sheet having an insulating coat with excellent heat resistance; and a method for manufacturing the same. This insulation-coated oriented magnetic steel sheet has an oriented magnetic steel sheet, and an insulating coat arranged on the surface of the oriented magnetic steel sheet, the insulating coat containing Si, P, O, and Cr, and at least one element selected from the group consisting of Mg, Ca, Ba, Sr, Zn, Al, and Mn. The XPS spectrum of the outermost surface of the insulating coat has peaks observed at Cr2p.sub.1/2 and Cr2p.sub.3/2.

Provided are an insulating-coated oriented magnetic steel sheet having an insulating coating of excellent heat resistance, and a method for manufacturing the same. This insulating-coated oriented magnetic steel sheet has an oriented magnetic steel sheet, and an insulating coating arranged on the surface of the oriented magnetic steel sheet. The insulating coating contains Si, P, and O, and at least one element selected from the group consisting of Mg, Ca, Ba, Sr, Zn, Al, and Mn, the K-absorption edge of the P in the insulating coating having an XAFS spectrum that exhibits three absorption peaks from 2156 eV to 2180 eV.

Provided are an insulating-coated oriented magnetic steel sheet having an insulating coating of excellent heat resistance, and a method for manufacturing the same. This insulating-coated oriented magnetic steel sheet has an oriented magnetic steel sheet, and an insulating coating arranged on the surface of the oriented magnetic steel sheet. The insulating coating contains Si, P, and O, and at least one element selected from the group consisting of Mg, Ca, Ba, Sr, Zn, Al, and Mn, the K-absorption edge of the P in the insulating coating having an XAFS spectrum that exhibits three absorption peaks from 2156 eV to 2180 eV.

An insulating coating-attached electrical steel sheet has, on at least one surface, an insulating coating including an insulating tensile coating layer A. A tension applied to the steel sheet by an insulating tensile coating layer having a coating weight of M/2 from a surface of the insulating tensile coating layer A is 0.80.sub.A or more, where M is a weight of the insulating tensile coating layer A, and .sub.A is the tension applied to the steel sheet by the insulating tensile coating layer A. The insulating coating-attached electrical steel sheet has excellent adhesion of the insulating coating. A method for manufacturing the insulating coating-attached electrical steel sheet is also provided.

In the present invention, there is provided a coating liquid for forming an insulation coating for a grain-oriented electrical steel sheet, including: a solvent; and one or two more layered clay mineral powders having a specific surface area of 20 m.sup.2/g or more. In addition, in the present invention, there is provided a grain-oriented electrical steel sheet including: a base metal; and an insulation coating provided on a surface of the base metal, in which the insulation coating contains SiO.sub.2, and one or two of Al.sub.2O.sub.3 and MgO, and has a porosity of 10% or less.