This invention provides a threaded connection for oil country tubular goods that exhibits excellent corrosion resistance and galling resistance, and a method for producing the threaded connection for oil country tubular goods. The method includes a Zn—Ni alloy plating layer formation step of forming a Zn—Ni alloy plating layer, and a chromate coating formation step of forming a chromate coating after the Zn—Ni alloy plating layer formation step. The chromate coating formation step includes a chromate treatment step and a drying step. The chromate coating formation step satisfy one or more conditions selected from the following conditions 1 to 3. Condition 1: stirring speed of the chromating solution in the chromate treatment step: a linear speed of 0.5 m/s or more; Condition 2: chromate treatment time in the chromate treatment step: less than 50 seconds; and Condition 3: drying temperature in the drying step: 60° C. or less.

An electrical steel sheet with an insulating film having excellent chromium elution resistance, even in the case where the insulating film is baked by utilizing rapid heating, which improves productivity, and a method for manufacturing the steel sheet. The insulating film contains Fe, Cr, an organic resin, and an organic reducing agent on at least one surface of an electrical steel sheet. A ratio of the Fe content to the Cr content (Fe/Cr) is 0.010 to 0.6 in terms of molar ratio in the insulating film.

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 sliding member includes, on a surface of a metal substrate, a surface-treated layer including a zinc-electroplated layer, a chemical conversion-treated layer, and a topcoat layer sequentially stacked on the metal substrate. The chemical conversion-treated layer includes chromium and oxygen. The topcoat layer includes at least one material selected from the group consisting of a silica compound, acrylic resin, polyurethane resin, epoxy resin, phenol resin, and melamine resin. A method of manufacturing the sliding member includes a step of forming, on a surface of the chemical conversion-treated layer, the topcoat layer including at least one material selected from the group consisting of a silica compound, acrylic resin, polyurethane resin, epoxy resin, phenol resin, and melamine resin.

A sliding member includes, on a surface of a metal substrate, a surface-treated layer including a zinc-electroplated layer, a chemical conversion-treated layer, and a topcoat layer sequentially stacked on the metal substrate. The chemical conversion-treated layer includes chromium and oxygen. The topcoat layer includes at least one material selected from the group consisting of a silica compound, acrylic resin, polyurethane resin, epoxy resin, phenol resin, and melamine resin. A method of manufacturing the sliding member includes a step of forming, on a surface of the chemical conversion-treated layer, the topcoat layer including at least one material selected from the group consisting of a silica compound, acrylic resin, polyurethane resin, epoxy resin, phenol resin, and melamine resin.

A surface treatment agent capable of forming a hexavalent chromium-free chemical conversion coating that can provide an excellent corrosion-resistant coating on various metallic materials; a metallic material having a surface treatment coating obtained therefrom; and a method of producing the same. A free fluorine ion-containing surface treatment agent for surface-treating a metallic material, which is obtained by mixing at least one supply source (A) of trivalent chromium-containing ions A; a supply source (B) of ions B that are at least one selected from titanium-containing ions and zirconium-containing ions; a water-soluble or water-dispersible compound (C) containing an alkoxysilyl group, an aromatic ring, a hydroxy group directly bonded to the aromatic ring, and at least one of primary, secondary, tertiary and quaternary amino groups, wherein the alkoxysilyl group is bonded to the nitrogen atom of the amino group directly or via an alkylene group; and a fluorine-containing compound (D) providing fluorine-containing ions.

A surface treatment agent capable of forming a hexavalent chromium-free chemical conversion coating that can provide an excellent corrosion-resistant coating on various metallic materials; a metallic material having a surface treatment coating obtained therefrom; and a method of producing the same. A free fluorine ion-containing surface treatment agent for surface-treating a metallic material, which is obtained by mixing at least one supply source (A) of trivalent chromium-containing ions A; a supply source (B) of ions B that are at least one selected from titanium-containing ions and zirconium-containing ions; a water-soluble or water-dispersible compound (C) containing an alkoxysilyl group, an aromatic ring, a hydroxy group directly bonded to the aromatic ring, and at least one of primary, secondary, tertiary and quaternary amino groups, wherein the alkoxysilyl group is bonded to the nitrogen atom of the amino group directly or via an alkylene group; and a fluorine-containing compound (D) providing fluorine-containing ions.

This invention provides a threaded connection for oil country tubular goods that exhibits excellent corrosion resistance and galling resistance, and a method for producing the threaded connection for oil country tubular goods. The method includes a ZnNi alloy plating layer formation step of forming a ZnNi alloy plating layer, and a chromate coating formation step of forming a chromate coating after the ZnNi alloy plating layer formation step. The chromate coating formation step includes a chromate treatment step and a drying step. The chromate coating formation step satisfy one or more conditions selected from the following conditions 1 to 3. Condition 1: stirring speed of the chromating solution in the chromate treatment step: a linear speed of 0.5 m/s or more; Condition 2: chromate treatment time in the chromate treatment step: less than 50 seconds; and Condition 3: drying temperature in the drying step: 60 C. or less.

This invention provides a threaded connection for oil country tubular goods that exhibits excellent corrosion resistance and galling resistance, and a method for producing the threaded connection for oil country tubular goods. The method includes a ZnNi alloy plating layer formation step of forming a ZnNi alloy plating layer, and a chromate coating formation step of forming a chromate coating after the ZnNi alloy plating layer formation step. The chromate coating formation step includes a chromate treatment step and a drying step. The chromate coating formation step satisfy one or more conditions selected from the following conditions 1 to 3. Condition 1: stirring speed of the chromating solution in the chromate treatment step: a linear speed of 0.5 m/s or more; Condition 2: chromate treatment time in the chromate treatment step: less than 50 seconds; and Condition 3: drying temperature in the drying step: 60 C. or less.

This invention relates to an aqueous solution and a method for preparing an organic protective coating on a Cr(lll) conversion layer which is localized on (anodized) aluminium (alloy) to enhance corrosion protection. The composition is an aqueous solution which contains water, an organic film forming agent and a corrosion inhibitor, wherein the corrosion inhibitor comprises or consists of at least one 2-arylriazole. According to the method of the present invention, the composition is used for post-treating of a Cr(lll) conversion layer on (anodized) aluminium (alloy). The invention further provides a modified Cr(III) conversion coating on (anodized) aluminium (alloy), which is producible or produced with the inventive method. The modified Cr(III) conversion coating according to the invention shows excellent corrosion protection, paint adhesion and electrical resistivity.