Electrodeposition of Cd-Ni alloys from acetate baths using a superimposed alternating current

Abstract

The electrodeposition of Cd−Ni alloys from some selected acetate baths has been investigated. The influences of the proportions of Ni2+ and Cd2+ ions in the bath, the operating current density and superimposed alternating current on the electrodeposited alloys have been examined. The study includes the effect of these variables on the cathodic polarization curves, current efficiency, chemical composition and surface morphology of the alloys. Under all conditions the electrodeposition process is of the anomalous type. An explanation of this phenomenon with the help of a comparison between the experimental and the calculated polarization curves is given. X-ray diffraction studies show that the nickel-rich alloys consist of Ni and β(Cd−Ni) phases, while the cadmium-rich alloys contain Cd, β(Cd−Ni) and Ni phases. The optimum bath composition and operating conditions for the electrodeposition of sound, smooth and bright Cd−Ni alloys have been identified.