Electrodeposition of Silver-Cadmium Alloys from Cyanide Electrolytes

Abstract

SUMMARYElectrodeposited layers of silver-cadmium alloys are reported to have increased hardness, electrical conductivity and tarnish resistance compared to silver. The standard electrode potentials of silver and cadmium are too far apart to permit codeposition from simple salt solutions, suitable complexing is necessary to bring the deposition potentials closer and facilitate codeposition. Results of the investigations with cyanide complexed solutions are presented in this paper. Electroplating experiments with varying concentrations of metal ions and operating conditions have shown the possibility of depositing alloys with a range of compositions. Characterisation of the deposits has been by X-ray diffraction, scanning electron microscopy and microhardness measurements. Voltammetric studies show the deposition of alloys of solid solution type at low concentrations of cadmium and a mixture of phases at higher concentrations.