The present invention addresses the problem of providing, a metal surface treatment agent capable of exhibiting excellent corrosion resistance and excellent coating adhesion in painted metal materials; and a metal surface treatment method using the metal surface treatment agent. The problem is solved by a pretreatment agent that is used in a pretreatment of a chemical conversion treatment performed for forming a chemical conversion coating on/over a surface of a metal material, the pretreatment agent containing: a metal alkoxide (A) containing at least one metal element selected from zirconium, titanium, vanadium, and aluminum; and at least one sulfonic acid (B) selected from methanesulfonic acid, ethanesulfonic acid, hydroxymethanesulfonic acid, and hydroxyethanesulfonic acid. The problem is also solved by a chemical conversion treatment agent that contains a zirconium alkoxide (a) and a zirconium-containing ion supply source (b), and has a pH of 1.5 to 6.5.

The present invention addresses the problem of providing, a metal surface treatment agent capable of exhibiting excellent corrosion resistance and excellent coating adhesion in painted metal materials; and a metal surface treatment method using the metal surface treatment agent. The problem is solved by a pretreatment agent that is used in a pretreatment of a chemical conversion treatment performed for forming a chemical conversion coating on/over a surface of a metal material, the pretreatment agent containing: a metal alkoxide (A) containing at least one metal element selected from zirconium, titanium, vanadium, and aluminum; and at least one sulfonic acid (B) selected from methanesulfonic acid, ethanesulfonic acid, hydroxymethanesulfonic acid, and hydroxyethanesulfonic acid. The problem is also solved by a chemical conversion treatment agent that contains a zirconium alkoxide (a) and a zirconium-containing ion supply source (b), and has a pH of 1.5 to 6.5.

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.

The present invention relates to a method for adjusting a passivation composition by determining the redox potential of a passivation composition as well as to a method for passivating metallic substrates by treatment with a passivation composition.

The present invention relates to a method for adjusting a passivation composition by determining the redox potential of a passivation composition as well as to a method for passivating metallic substrates by treatment with a passivation composition.

A grain-oriented electrical steel sheet according to an aspect of the present invention includes: a steel sheet 1; an intermediate layer 4 containing Si and O, arranged on the steel sheet; and an insulation coating 3 arranged on the intermediate layer 4, in which the intermediate layer 4 contains a metal phosphide 5, a thickness of the intermediate layer 4 is 4 nm or more, and an abundance of the metal phosphide 5 present is 1% to 30% by cross-sectional area fraction in a cross section of the intermediate layer 4.

A method of processing a metal member having a passivation film on its surface is provided. The method includes a step of heating the metal member for a predetermined period at a temperature of 300 C. or higher.

A method of processing a metal member having a passivation film on its surface is provided. The method includes a step of heating the metal member for a predetermined period at a temperature of 300 C. or higher.

The coating film-forming composition includes an aromatic compound having an amino group and an aromatic ring in one molecule, and thio compound (sulfur oxoacids having a pKa of 1.9 or less and salts thereof are excluded). pH of the coating film-forming composition is 4 to 10. The thio compound is preferably one that ionized to form anions in a solution, and thiosulfate and thiocyanate are especially preferable. By bringing the coating film-forming composition into contact with the surface of a metal member, a coating film is formed on the surface of the metal member, so that a surface-treated metal member can be obtained.