Nihon Parkerizing Co., Ltd.

Nissan Motor Company Limited

Henkel Corporation

Akihiko Hasebe

Norifumi Hatano

Katsuya Yamamoto

Hiroshi Okita

Akira Nishihara

Ryohsuke Sako

Kazuyuki Oyama

Oyama Kazuyuki

Composition and process for chromating metal surfaces

A colorless chromate coating film is formed on a bright aluminum wheel by subjecting the surface of an aluminum wheel to a cathodic electrolytic treatment in an acidic aqueous solution containing not less than 2 g/l of hexavalent chromium ions, 20 to 2,000 ppm of sulfate ions, 10 to 400 ppm of fluorine (F) as fluoride and not less than 20 ppm of zirconium ions at a pH of 0.6 to 1.7 at a current density of 0.5 to 15 A/dm.sup.2 for at least 30 seconds, thereby forming a coating film with a chromium coating amount of 50 to 250 mg/m.sup.2.

Process for forming colorless chromate coating film on bright aluminum

A durable hydrophilic surface can be formed on metals by coating them with a composition containing a first water soluble polymer based on polyacrylamide, a second water soluble polymer with at least 60 mole percent of ionizable groups such as acids and quaternary ammonium salts, and a cross linking agent. Water soluble chromium and zirconium salts that can form complexes with the first water soluble polymer are preferred crosslinking agents. The invention is particularly useful for aluminum to be used in heat exchangers.

Metal surface hydrophilicizing process and composition

Growing community of inventors

Kanagawa, Japan

Akihiko Hasebe