Black chromate-treatment solution for Zn-Ni alloy plated film
AssigneeDipsol Chemicals Co., Ltd.
InventorsSeiji Kishikawa, Takashi Yamamoto
Life of this patent
Estimating the term…
Abstract
A black chromate-treatment solution for Zn-Ni alloy plated film comprises 1 to 100 g/l of hexavalent chromium, 1 to 100 g/l of hydrochloric acid residues and/or sulfuric acid residues, 1 to 100 g/l of nitric acid residues and 1 to 100 g/l of at least one metal selected from the group consisting of iron, nickel, cobalt and copper. The chromate-treatment solution permits the formation of a uniform black chromate conversion film on a Zn-Ni alloy plated film having an Ni content ranging from 8 to 20% by weight without using any silver ions in a substantial amount and the resulting black film is excellent in corrosion resistance.
Claims6
A method for forming a black chromate film on a Zn-Ni alloy plated film, comprising bringing a Zn-Ni alloy plated film having a Ni content ranging from 8 to 20% by weight into contact with a black chromate-treatment solution which comprises 1 to 100 g/l of hexavalent chromium, 1 to 100 g/l of hydrochloric acid residues, 1 to 100 g/l of nitric acid residues 1 to 100 g/l of at least one metal selected from the group consisting of iron, nickel, cobalt and copper, and a balance of water, and which solution is substantially free of silver ions.
A method for forming a black chromate film on a Zn-Ni alloy plated film, comprising bringing a Zn-Ni alloy plated film having a Ni content ranging from 8 to 20% by weight into contact with a black chromate treatment solution at a temperature ranging from 15.degree. to 50.degree. C. for 30 to 300 seconds, the black chromate-treatment comprising 10 to 50 g/l of hexavalent chromium, 10 to 100 g/l of hydrochloric acid residues, 5 to 50 g/l of nitric acid residues, 5 to 50 g/l of at least one metal selected from the group consisting of iron, nickel, cobalt and copper, and a balance of water, and having a pH ranging from 0.5 to 2.5, and which solution is substantially free of silver ions.
Dependencies are inferred from the claim text.