Nkk Corporation

Jfe Steel Corporation

Nkk Cororation

Toru Imokawa

Takayuki Urakawa

Michitaka Sakurai

Masaaki Yamashita

Masayasu Nagoshi

Toyofumi Watanabe

Junichi Inagaki

Takahiro Kubota

Etsuo Hamada

Satoshi Hashimoto

Shuji Nomura

Hideharu Koga

Kaoru Sato

Yoshiharu Sugimoto

Masaru Sagiyama

Shoichiro Taira

Nobue Fujibayashi

Akira Gamou

Yoichi Miyakawa

Akira Hiraya

Masahiro Iwabuchi

Shunsaku Node

Jun-ichi Inagaki

The present invention provides a chromium-free surface treatment agent, comprising: a resin compound having a specific bisphenol skeleton; cationic urethane resin emulsion; silane coupling agent; an organic titanium chelate compound; a quadrivalent vanadyl compound; a molybdic acid compound; and water, wherein these components are blended at predetermined ratios such that pH value of the surface treatment agent is in the range of 4 to 5. The one-pack type chromium-free surface treatment agent of the present invention exhibits good stability during storage and is capable of forming on a metal material surface a coating film excellent in corrosion resistance at a bending-processed portion of a steel sheet, solvent resistance and paintability after alkali degreasing.

Surface treatment agent for zinc or zinc alloy coated steel sheet, zinc or zinc alloy coated steel sheet, and method of producing the steel sheet

The present invention provides a chromium-free surface treatment liquid which enables forming, on a metal material surface, a film excellent in corrosion resistance at bent portions of a steel sheet, solvent resistance, coating properties after alkaline degreasing, and sweat resistance. The surface treatment liquid contains a resin compound having a specific bisphenol skeleton, a cationic urethane resin emulsion, a silane coupling agent, an organic titanium chelate compound, a quadrivalent vanadyl compound, a molybdate compound, a fluorine compound, and water at predetermined proportions. The pH of the surface treatment liquid is in the range of 4 to 5.

Surface treatment liquid for zinc or zinc alloy coated steel sheet, zinc or zinc alloy-coated steel sheet, and method for manufacturing the same

The invention provides a galvannealed steel sheet which has an oxide layer having 10 nm or larger thickness on the plateau of the coating layer flattened by temper rolling. With the use of the galvannealed steel sheet, no powdering occurs during press-forming, and stable and excellent sliding performance is attained. By selecting the area percentage of the plateau of the flattened coating layer to a range from 20 to 80%, making the coating layer single layer of &dgr; phase, and letting &zgr; phase exist in the &dgr; phase, further improved sliding performance and anti-powdering property are obtained.

Galvannealed steel sheet and method for manufacturing the same

A zinciferous coated steel sheet comprises a steel sheet, a zinciferous coating layer formed on the steel sheet, a Fe--Ni--Zn--O film formed on the zinciferous coating layer, and an oxide layer formed on a surface portion of the Fe--Ni--Zn--O film. The method comprises providing an electrolyte of an acidic sulfate aqueous solution, carrying out an electrolysis treatment in the electrolyte under a current density ranging from 1 to 150 A/dm.sup.2, and carrying out an oxidation treatment to a surface of the zinciferous coated steel sheet.

Zinciferous coated steel sheet and method for producing the same

Zinciferous plated steel sheet and method for manufacturing same

A method for manufacturing a zinciferous plated steel sheet, comprises: forming a zinciferous plating layer on a steel sheet; and forming an Fe--Ni--O film on the zinciferous plating layer. The Fe--Ni--O film is formed by carrying out electrolysis with the steel sheet as a cathode in an aqueous solution, dipping the steel sheet in an aqueous solution, or spraying a mist on a surface of the zinciferous plating layer.

A method for producing a zinc-electroplated steel sheet comprising the steps of: pickling a steel sheet with a pickling solution so as to deposit a tin of an amount of 0.5 mg/m.sup.2 to less than 10 mg/m.sup.2 on the steel sheet; and zinc-electroplating the pickled steel sheet.

Zinc-electroplated steel sheet and method thereof

A zinc-electroplated steel sheet comprises a steel sheet; a tin layer which is formed on the steel sheet, the tin layer having a deposition amount of 0.5 mg/m.sup.2 to less than 10 mg/m.sup.2 ; and a zinc-electroplating layer which is formed on the tin layer. A method for producing a zinc-electroplated steel sheet comprising the steps of: pickling a steel sheet with a pickling solution so as to deposit a tin of an amount of 0.5 mg/m.sup.2 to less than 10 mg/m.sup.2 on the steel sheet; and zinc-electroplating the pickled steel sheet.

Zinc-electroplated steel sheet

Growing community of inventors

Tokyo, Japan

Toru Imokawa