Patent ID: 11905613
Assignee: COVENTYA S.P.A.
Field: Surface technology, coating (Chemistry)
Classification: CPC C | IPC C

Claim 18:
19. An electroplating bath for depositing chromium metal coating on a substrate or chromium metal alloy coating on a substrate consisting essentially of:
(a) 50 to 400 g/L (0.164 M to 1.314 M) of at least one trivalent chromium salt,
(b) 100 to 400 g/L (2.17 M to 8.68 M) of at least one complexing agent, wherein the at least one complexing agent is selected from the group consisting of carboxylic acids and carboxylate salts and wherein the at least one carboxylic acid or carboxylate salt is present as the sole at least one complexing agent in the electroplating bath,
(c) 5 to 50 g/L (0.0425 M to 0.425 M) of at least one halogen salt,
(d) 70 to 110 g/L of ammonia;
(e) 0.5 to 10 g/L of additives, wherein the additives comprise a quaternary ammonium compound, and
(f) optionally an alloy former,
wherein the electroplating bath has a pH from 4 to 7 and is substantially free of divalent sulphur compounds and boric acid, its salts and/or derivatives and wherein the molar ratio of the complexing agent to the trivalent chromium salt is from 10:1 to 15:1,
wherein the electroplating bath is substantially free of aluminium ions and is substantially free of chloride ions;
whereby, when the substrate is immersed in the electroplating bath and an electrical current is applied, the substrate is deposited with a chromium metal coating or a chromium metal alloy coating.