Henkel Corporation

Nihon Parkerizing Co., Ltd.

Mitsubishi Kasei Corporation

Noriaki Yoshitake

Kenshi Saeki

Takao Ogino

Takumi Honda

Kensuke Mizuno

Hitoshi Ishii

Takayuki Aoki

Hiroshi Okita

Yukio Tsuge

Akira Nishihara

Haruo Iizuka

Shotaro Tsuda

Yoshiyuki Murasawa

The protection against black and white rust on zinciferous surfaces by a conventional chromating treatment is improved by drying into place on the zinciferous surface before chromating a pre-treatment composition that contains hexavalent chromium ion plus one or more salts of nickel and cobalt, in an amount to produce an add-on of 0.5 to 100 mg/m.sup.2 of metal.

Pre-treating zinciferous surfaces before conventional chromating to

Composition and process for substitutionally plating zinciferous surfaces

Pretreatment for zinc and zinc alloy prior to chromating

Zinciferous surfaces, particularly those of galvanized steel, may be effectively protected against corrosion, either as treated or after painting, while remaining easy to weld, by contact with an aqueous solution containing chromium in both +6 and +3 valence states, phosphate, a tertiary alcohol or similar oxidation stable, water soluble organic compound as a wetting agent, and a silane coupling agent, followed by drying with a film from the solution still in place on the surface. A thin coating containing 10-200 mg/m.sup.2 of chromium is formed on the surface to provide a protective layer that is also an excellent base for paint.

Surface treatment for zinciferous surfaces

The resistance of chromated zinc surfaced steel objects, particularly plates and sheets, to extraction of hexavalent chromium by alkaline degreasing solutions used on the chromated objects, can be substantially increased by utilizing an aqueous acidic liquid chromating composition containing (A) about 9.6 to about 96 g/L, expressed as its stoichiometric equivalent as chromic acid, of total chromium; (B) about 2 to about 35 g/L of trivalent chromium ions; (C) about 1 to about 128 g/L of phosphate ions; and (D) about 0.3 to about 4 g/L of fluorozirconate ions, with the chromium ratio in the aqueous acidic liquid composition being about 0.41 to about 0.70, the chromic acid/fluorozirconate weight ratio being about 10 to about 40, and the PO.sub.4 /Cr.sup.+3 ratio being greater than about 0.03, greater than or equal to about {(9.2) (the chromium ratio)-4.0}, and less than or equal to about {(9.2) (the chromium ratio)-1.2}. . . The corrosion resistance of the coatings formed can be further improved if the chromating composition also contains about 0.1 to about 200 g/L of dispersed silica.

Composition and process for chromating galvanized steel and like

The present invention relates to a process for surface treatment for cathodic electrodeposit coating of a zinc-plated or zinc alloy-plated steel sheet comprising coating and drying a protective coating material on said steel sheet chromate-treated beforehand, to form a protective film before subjecting the sheet to the cathodic electrodeposit coating, which comprises coating a protective coating material having as a principal constituent of film-forming organic component a block isocyanate-containing prepolymer containing in one and the same molecule respectively at least one blocked isocyanate group, hydroxyl group, and tertiary amono group and containing 10-100 parts by weight of silica sol relative to 100 parts by weight of said prepolymer, in an amount of 0.3 g-4 g/m.sup.2, and then heat-drying the same.

Process for treating plated steel sheet

An aqueous solution of a reducing agent is applied to a chromate coated metal surface to reduce the extent to which the chromate coating undergoes dissolution during a subsequent cleaning process.

Treatment of chromate coating

Growing community of inventors

Kanagawa, Japan

Noriaki Yoshitake