Electrodeposition of Zinc-Cobalt Alloy from an Alkaline Sulfate Bath Containing Triethanolamine and Gelatin

The results reported here pertain to the development of a noncyanide and ammonia-free alkaline sulfate bath containing TEA as a complexer and gelatin as a brightener for producing bright Zn-Co alloy containing 0.6-1.0% Co. Zinc-cobalt alloy deposits containing 0.6-1.0% cobalt electrodeposited from a...

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Bibliographic Details
Published in:Metal finishing 1998-04, Vol.96 (4), p.24,26-24,27
Main Authors: Narasimhamurthy, V., Sheshadri, B.S.
Format: Article
Language:English
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Summary:The results reported here pertain to the development of a noncyanide and ammonia-free alkaline sulfate bath containing TEA as a complexer and gelatin as a brightener for producing bright Zn-Co alloy containing 0.6-1.0% Co. Zinc-cobalt alloy deposits containing 0.6-1.0% cobalt electrodeposited from an alkaline sulfate bath containing TEA and gelatin were smooth, uniform, and bright. The deposition potential for alloy deposition was more negative to zinc. The cathodic current-potential curve during alloy deposition lies to the right of zinc deposition potential curve. Electrodeposition of zinc-cobalt alloy is of the anomalous type. The Co content in the alloy was always less than that of Co content in the bath solution. Increase in current density decreases percent Co in the alloy. Increase in temperature of the bath and stirring increase the percent Co in the alloy. Increase in the concentrations of TEA and gelatin decreases percent Co in the alloy. Maximum deposition rate was obtained at a concentration of 40 g/L TEA and 4 g/L of gelain. Increase in the thickness of the alloy leads to a constant alloy composition. The CCE increases with temperature and stirring and decreases with Cd. The application in view is to the development of high corrosion resistant steel for automotive applications.
ISSN:0026-0576
1873-4057
DOI:10.1016/S0026-0576(97)86638-X