Electrideposition of Co-Ni Alloy from Citrate-Acetate Bath on Steel Substrate -Part I :Deposition circuits

Cobalt-Nickel electrodeposition on a steel substrate was carried out from solutions containing nickel sulfate, cobalt sulfate, sodium sulfate and sodium citrate and sodium acetate with 1:2 and 2:1 ratio respectively. The study deals with the influence of bath composition, current density, pH, time of deposition, temperature and additives such as saccharin and thiourea on cathodic current efficiency. Throwing power and throwing index were calculated for the best bath. The efficiency for deposition from citrate-acetate mixed bath is higher than that reported for the separated citrate and acetate baths. The codeposition of this alloy from these solutions can be classified as anomalous plating system where Co is preferentially deposited.