A treatment agent for chromium-free insulating coating formation suitable for forming an insulating coating on a surface of a grain-oriented electrical steel sheet. The treatment agent includes components (A), (B), (C), and (D). The component (B) is contained in an amount of 50 to 150 parts by mass on a SiO.sub.2 solid basis, and the component (C) is contained in an amount of 5.0 parts by mass or more on an elemental metal basis, the amounts being based on 100 parts by mass, on a solid basis, of the component (A). The component (D) is contained in an amount that a molar ratio of M.sup.2+ and M.sup.3+, each being a metal element in the treatment agent for chromium-free insulating coating formation, to a phosphorus element P satisfies a specified relationship, and the treatment agent for chromium-free insulating coating formation has a pH of less than 4.5.

Provided are a treatment liquid for a black trivalent chromium conversion coating, and a trivalent chromium-containing water-soluble liquid for finishing treatment, achieving excellent corrosion resistance and scratch resistance without containing a cobalt compound, with high stability and adequate consideration for environmental issues; and a method for treating a metal substrate using the same. The treatment liquid for a black trivalent chromium conversion coating on the surface of a metal substrate contains a trivalent chromium compound, two or more organic acids or organic acid salts, or one or more organic sulfur compounds, and nitrate ions, and contains no cobalt compound.

Provided are a treatment liquid for a black trivalent chromium conversion coating, and a trivalent chromium-containing water-soluble liquid for finishing treatment, achieving excellent corrosion resistance and scratch resistance without containing a cobalt compound, with high stability and adequate consideration for environmental issues; and a method for treating a metal substrate using the same. The treatment liquid for a black trivalent chromium conversion coating on the surface of a metal substrate contains a trivalent chromium compound, two or more organic acids or organic acid salts, or one or more organic sulfur compounds, and nitrate ions, and contains no cobalt compound.

A method includes providing a workpiece with at least one surface having an anodized aluminum coating and a trivalent chromium sealant. The at least one surface of the workpiece is submerged in a post-treatment sealant solution for 0.5 to 20 minutes. The sealant composition consists essentially of a corrosion inhibitor formulation, a water soluble polymer, an organic complexing agent, and an oxidant. The corrosion inhibitor formulation is formulated from at least one anodic corrosion inhibitor compound, at least one cathodic corrosion inhibitor compound, or a combination thereof. A concentration of each of the corrosion inhibitor formulation, the water soluble polymer, the organic complexing agent, and the oxidant is each in a range of 1-50 mM.

A method includes providing a workpiece with at least one surface having an anodized aluminum coating and a trivalent chromium sealant. The at least one surface of the workpiece is submerged in a post-treatment sealant solution for 0.5 to 20 minutes. The sealant composition consists essentially of a corrosion inhibitor formulation, a water soluble polymer, an organic complexing agent, and an oxidant. The corrosion inhibitor formulation is formulated from at least one anodic corrosion inhibitor compound, at least one cathodic corrosion inhibitor compound, or a combination thereof. A concentration of each of the corrosion inhibitor formulation, the water soluble polymer, the organic complexing agent, and the oxidant is each in a range of 1-50 mM.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2), the insulating film (3) containing a polyvalent metal phosphate and Fe. A maximum value of a parameter Q expressed by Q=C.sub.FeO/C.sub.P is equal to or less than 1.3 times and equal to or more than 1.09 times an average value of the parameter Q in a region from a first depth from a surface of the insulating film to a second depth, C.sub.FeO denoting a proportion (atom %) of Fe bonded to O relative to all elements, and C.sub.P denoting a proportion (atom %) of P relative to all elements. The first depth is 20 nm from the surface, and the second depth is a depth where the proportion of P is equal to a proportion of metal Fe.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2), the insulating film (3) containing a polyvalent metal phosphate and Fe. A maximum value of a parameter Q expressed by Q=C.sub.FeO/C.sub.P is equal to or less than 1.3 times and equal to or more than 1.09 times an average value of the parameter Q in a region from a first depth from a surface of the insulating film to a second depth, C.sub.FeO denoting a proportion (atom %) of Fe bonded to O relative to all elements, and C.sub.P denoting a proportion (atom %) of P relative to all elements. The first depth is 20 nm from the surface, and the second depth is a depth where the proportion of P is equal to a proportion of metal Fe.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). The insulating film (3) contains a phosphates of one or more selected from the group consisting of Al, Zn, Mg and Ca. The phosphate exhibits a specific peak having a top within a range of 26 ppm to 16 ppm in a solid .sup.31P-NMR spectrum, and a proportion of an integrated intensity of the specific peak relative to an integrated intensity of all peaks in the solid .sup.31P-NMR spectrum is 30% or more.

An electrical steel sheet (1) includes a base material (2) of electrical steel, and an insulating film (3) formed on a surface of the base material (2). The insulating film (3) contains a phosphates of one or more selected from the group consisting of Al, Zn, Mg and Ca. The phosphate exhibits a specific peak having a top within a range of 26 ppm to 16 ppm in a solid .sup.31P-NMR spectrum, and a proportion of an integrated intensity of the specific peak relative to an integrated intensity of all peaks in the solid .sup.31P-NMR spectrum is 30% or more.

The present invention provides a method of tin-plating a copper alloy for electric or electronic parts and automobile parts which has excellent insertion force, heat-resistant peeling, and solderability, and a tin-plating material of a copper alloy manufactured therefrom.