Effect of bath constituents and some plating variables on the electrodeposition of cadmium from acidic chloride baths

Abstract

The electrodeposition of cadmium from acidic chloride electrolytes containing 0.3 M CdCl 2·(5/2)H 2O, 0.1 M HC1, 0.4 M H 3BO 3 and 2.0 M NH 4Cl (bath I) was investigated. Electrodeposition in the presence of 0.5 M sodium potassium tartrate and 5 g gelatin 1 −1 as organic additives (bath II) was also studied. The effects of the bath constituents, the plating current density i, the duration t and the pH on the cathodic polarization, the efficiency and the throwing power of cadmium electroplating from each bath, as well as on the morphology and the microhardness of the as-plated cadmium electrodeposits, are discussed. It was found that the additive-containing bath II yields more compact finer-grained brighter and harder plates than the additive-free bath I. The optimum conditions for cadmium electroplating from bath II at 25 °C are as follows: i, 1.0–1.6 A dm −2 5–15 min; pH 3.8–4.5.