WHITE CHROMATE TREATMENT EXCELLENT IN CHROMIUM ELUTING RESISTANCE, CORROSION RESISTANCE AND COATING SUITABILITY

Japanese Patent JP3069027

B2

PROBLEM TO BE SOLVED: To provide a chromate treating method improving the corrosion resistance and coating suitability of a nonferrous metal plated steel sheet or a nonferrous metallic material and imparting beautiful appearance after treatment and excellent chromium eluting resistance thereto.
SOLUTION: The surface of a nonferrous metal plated steel sheet or a nonferrous metallic material is coated with a chromate treating soln. contg. reduced chromic acid in which the compositional ratio of Cr3+/Cr6+ is regulated to 3/7 to 7/3 by 7.5 to 100g/L expressed in terms of anhydrous chromic acid, phosphoric acid compounds by 0.5 to 3.0 weight ratio to the one expressed in terms of anhydrous chromic acid in reduced chromic acid, silica and/or the colloidal silica of silicate by 0.5 to 5.0 weight ratio to the one expressed in terms of anhydrous chromic acid in reduced chromic acid, at least one kind selected from phosphonic acid and the salts thereof by 1.0 to 20g/L and water soluble or water dispersible organic high polymer compounds by >30g/L, and is dried under heating. Thus, a white chromate film having beautiful appearance after the treatment and excellent in chromium eluting resistance, corrosion resistance and coating suitability can be obtd.

Teruaki Izaki
Masahiro Fuda
Hidekazu Takei
Haruhiko Eguchi

JP17081295A

July 24, 2000

July 06, 1995

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Nippon Steel Corporation

C23C22/27; C23C22/30; C23C22/33; (IPC1-7): C23C22/30; C23C22/27; C23C22/33

JP7180065A
JP63310975A
JP6306630A
JP63270480A
JP324278A

Yu Shiina (1 person outside)

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