Electrochemical and Surface Analytical Studies of Silver Deposits for Industrial Electroplating

摘要

For silver plating, mainly silver cyanide solutions are used and this is extensively treated in the literature. Yet, in view of the growing concern for environmental problems, they will have to be replaced because of their toxic properties. In the present work, the appropriateness of thio-sulphate (S_2O_3~(2-)), a complexing agent for silver of common use in photographic applications, as an alternative for cyanide in electroplating baths is investigated. The kinetic characteristics of the reduction are determined, since they fix at which rate the plating can proceed. Prior to the kinetic study, requiring measurements in solutions of varying composition, the thermodynamic data on complex formation between Ag~+ and S_2O_3~(2-) ions are analysed. And finally, the composition and the morphology of the silver deposits are examined as a function of the plating conditions. Electrochemical and analytical physical techniques are used.