Nkk Corporation

Nkk Cororation

Takayuki Urakawa

Toyofumi Watanabe

Toru Imokawa

Michitaka Sakurai

Masaaki Yamashita

Satoru Ando

Junichi Inagaki

Satoshi Hashimoto

Hideharu Koga

Yoshiharu Sugimoto

Masaki Abe

Masaru Sagiyama

Akira Hiraya

Shuji Nomura

Jun-ichi Inagaki

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

There is disclosed a method of manufacturing a plated steel sheet with a Zn--Cr alloy plating, including the steps of preparing a plating bath having a pH of 1 to 3 by adding 50 to 250 g/l of ammonium sulfate to a sulfuric acid plating bath and forming a Zn--Cr alloy plating film on a steel sheet using the resultant plating bath.

Method of manufacturing plated steel sheet with zn-cr alloy plating

There is disclosed a method of manufacturing a plated steel sheet with a Zn--Cr composite plating, wherein a total of 0.01 to 300 g/l of at least one type of salt having a pH buffering action in a pH range of 2 to 6 in a bath containing only zinc are added to an acidic Zn--Cr composite plating bath containing zinc ions and trivalent chromium ions to prepare a plating bath, and plating film is formed on a steel sheet using the resultant plating bath.

Method of manufacturing plated steel sheet with Zn-Cr composite plating

A method for continuously manganese-electroplating or manganese-alloy-electroplating a steel sheet, which comprises the steps of: using a manganese electroplating solution or a manganese alloy electroplating solution, using an insoluble anode, and causing a DC electric current to flow between the insoluble anode and a steel sheet during travelling through the electroplating solution while replenishing the manganese electroplating solution or the manganese alloy electroplating solution with manganese ions or manganese alloy ions, thereby forming a manganese plating layer or a manganese alloy plating layer on at least one surface of the steel sheet. As the insoluble anode, a hydrogen gas diffusing insoluble anode is used. By continuously supplying a hydrogen gas to the hydrogen gas diffusing insoluble anode, an oxidation reaction of the hydrogen gas is caused to take place at the hydrogen gas diffusing insoluble anode, thereby preventing the production of multivalent manganese in the solid state or the ionic state and having at least trivalence in the manganese electroplating solution or the manganese alloy electroplating solution.

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Fukuyama, Japan

Takayuki Urakawa