ELECTRODEPOSITION OF BRIGHT ZINC-COBALT ALLOY, ELECTROPLATES, ELECTROPLATING, ELECTRODEPOSITION

Zinc-cobalt alloys provide corrosion resistance for the ferrous based metals. An acidic electrolyte for zinc-cobalt electrodeposition is examined in the present work. The effects of variations in electrolyte composition, in electrolyte temperatura, pH and agitation on electrodeposit composition have been studied, as well as the current density influence. It was found that the following electrolyte gave the optimum results: 79 g.l-1 ZnCl2, 15.3 g.l-1 CoCl2.6H2O, 160 g.l-1 KCl, 25 g.l-1 H3BO3 and 5-10 cm3.l-1 of an organic additive (caffeine, coumarin and sodium lauryl-sulphonate). The operating conditions were: pH = 5,6, temperature: 30-degrees-C, current density: 0,025-0,035 A.CM-2, anode: pure zinc, agitation: slowly with air and filtration: continous. The throwing power and cathode current efficiency of the electrolyte were also studied. This electrolyte yielded zinc-cobalt alloys white and lustrous and had a cobalt content of 0,5-0,8 %.