Kawasaki Steel Corporation

Takahisa Yoshihara

Akira Matsuda

Hajime Kimura

Kazuaki Kyono

Akira Komoda

Toshio Irie

Kuniaki Sato

Shunichi Harada

Hisao Yasunaga

Shigeo Kurokawa

Minari Goto

Hideo Komura

Kazuaki Miyachi

Yoshinori Fujita

Yasuhiro Hirooka

Syoji Shijima

Kazuaki Kyohno

Steel strips are electrogalvanized with a Zn-Ni alloy deposit having the desired nickel content in a consistent manner for a long time by placing separate Zn and Ni soluble anodes in a chloride plating bath comprising major proportions of ZnCl.sub.2 and NiCl.sub.2 in an Ni/(Zn+Ni) ratio between 0.08 and 0.20 and a total molar amount of Zn+Ni of from 1 to 4 moles per liter, and b mole per liter of KCl and a mole per liter of NH.sub.4 Cl as shown in FIG. 8; passing a steel strip through the bath; and introducing currents to the soluble Zn and Ni anodes in a specific ratio given by equation (2).

Production of Zn-Ni alloy plated steel strips

Steel strips are electroplated with a Zn-Fe base alloy containing 10 to 30% by weight of iron in a chloride bath which contains zinc and ferrous chlorides to give a total concentration of zinc and ferrous ions of from 1.0 mol/l to the solubility limit with a weight ratio of Fe.sup.2+ /Zn.sup.2+ between 0.10 and 0.35, and chloride ions in a total concentration of at least 6.0 mol/l under electrolytic conditions: pH 1.0-6.0, current density 80-200 A/dm.sup.2, and relative flow velocity 30-200 m/min. The bath may further contain a polycarboxylic acid such as citric acid and a Zn-Fe-P alloy plating may be deposited when the bath further contains hypophosphorous acid.

Process for preparing Zn-Fe base alloy electroplated steel strips

A counter flow device for a plating apparatus including a rotary drum with its substantially half part immersed in a plating solution in a plating bath, about which a metallic strip to be plated passes in synchronism with rotation of said rotary drum and anodes spaced apart by radial gaps from the strip for causing electric current to flow between the strip and the anodes. According to the invention the counter flow device comprises a bottom nozzle arranged at a bottom of the bath and directing in a direction substantially opposite to an entering direction of the strip thereat and a top nozzle having a nozzle opening whose tip end is immersed in the proximity of a surface of the plating solution at a location where the strip leaves the plating solution, thereby ensuring uniform counter flows over entire gaps between the metallic strip and anodes to remarkably increase critical current density in plating and advantageously realize uniform plating.

Counter flow device for electroplating apparatus

One-side zinc hot dipped steel sheets are produced by coating one surface of a steel sheet with an aqueous slurry of an anti-plating agent based on MgO, alkali metal silicates, boric acid, MOH (M is an alkali metal) and the like and containing such additives as TiO.sub.2 and Al.sub.2 O.sub.3, heating the coated sheet for drying and baking, immersing the steel sheet with an anti-plating film in a molten zinc bath to zinc plate the other surface of the sheet, wetting the anti-plating film, and bending the steel sheet to cause the anti-plating film to peel off, thereby removing the anti-plating film from the steel sheet. This invention carries out the coating and baking of the anti-plating agent such that it is baked to a film having a thickness of 20 to 60 microns at a temperature of 750.degree. C. to about 930.degree. C.

One-side zinc hot dipping process using an anti-plating agent

Disclosed is an anti-plating agent for use in hot-dip plating process, having the following two kinds of composition. The composition of the first kind includes an alkali silicate; boric acid, and alkali hydroxide, magnesia and/or magnesium hydroxide, titania and/or titanium hydroxide, and at least one compound selected from a group consisting of alumina, aluminium hydroxide and alumina zol. The composition of the second kind includes an alkali silicate, boric acid, alkali hydroxide, magnesia and/or magnesium hydroxide, alumina and/or aluminium hydroxide, and at least one kind of titanium oxide and titanium complex oxide and/or at least one kind of zirconium oxide and zirconium complex oxide. These anti-plating agents have a good anti-plating effect and permit an easy separation of the coating film and, hence, can suitably be used in one-side hot-dip plating of steel sheets.

Anti-plating agent for one-side hot-dip plating process

A composite zinc-aluminum dispersion plated steel sheet and a method of producing same are disclosed. The plated steel sheet comprises an electrolytical zinc plated layer containing 1.5 to 70% by weight of aluminum dispersed therein. The method comprises adding aluminum powder to an electrolytical zinc plating bath composition, dispersing the aluminum powder into the plating bath to provide a composite zinc-aluminum dispersion plating bath, and electrolytical treating a steel sheet in the composite zinc-aluminum dispersion plating bath while agitating it. The plated steel sheet enhances corrosion resistances and does not show any spangles which impair the appearances after subsequent painting of the plated steel sheet.

Steel substrate electroplated with Al powder dispersed in Zn

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Chiba, Japan

Takahisa Yoshihara