Claims
- 1. A trivalent aqueous chromium plating solution comprising trivalent chromium ions in a concentration of at least 0.2 M, sulphate ions in a concentration of at least 0.3 M, a weak complexing agent for said trivalent chromium ions in a concentration of at least 0.1 M and selected from the group consisting of hypophosphite ions and glycine, fluoride ions in a concentration of at least 0.025 M, and chloride ions in a concentration of at least 0.1 M.
- 2. A trivalent chromium plating solution according to claim 1 wherein the weak complexing agent is in a concentration of from 0.25 to 3 M.
- 3. A trivalent chromium plating solution according to claim 2 containing ammonium ions in a concentration of from 1 to 7 M.
- 4. A trivalent chromium plating solution according to claim 3 containing ammonium ions in a concentration of at least 5 M.
- 5. A trivalent chromium plating solution according to claim 1 which contains additionally boric acid.
- 6. A trivalent chromium plating solution according to claim 1 which contains chloride ions in a concentration of from 0.1 to 5.0 M.
- 7. A trivalent chromium plating solution according to claim 6 containing chloride ions in a concentration of from 0.5 to 5.0 M, the molar ratio of chloride to sulphate being from 1:60 to 5:1.
- 8. A trivalent chromium plating solution according to claim 6 wherein said solution is substantially bromide-free.
- 9. A method for electrodepositing chromium on a substrate which comprises immersing said substrate as the cathode in an aqueous electrolyte solution comprising water, trivalent chromium ions in a concentration of at least 0.2 M, sulphate ions in a concentration of from 1 to 6 M, a weak complexing agent for said trivalent chromium ions in a concentration of at least 0.1 M and selected from the group consisting of hypophosphite ions and glycine, fluoride ions in a concentration of at least 0.025 and chloride ions in a concentration of at least 0.1 M, and passing an electric current through said solution thereby to deposit said trivalent chromium ions on said substrate.
Priority Claims (1)
Number |
Date |
Country |
Kind |
12776/75 |
Mar 1975 |
GBX |
|
Parent Case Info
This application is a continuation-in-part of application Ser. No. 668,443, filed Mar. 19, 1976 and now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
3917517 |
Jordan et al. |
Nov 1975 |
|
3954574 |
Gyllenspetz et al. |
May 1976 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
219,356 |
Aug 1968 |
SUX |
Non-Patent Literature Citations (1)
Entry |
Larissa Domnikov, Metal Finishing, pp. 107-109, Jun. 1966. |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
668443 |
Mar 1976 |
|