Electrodeposition of Silver Alloy Powders on Rotating and Vibrating Cathodes

SummaryA detailed study of the manufacture of Ag-Sn and Ag-Sn-Cu powder deposits at rotating cylinder and vibrating cathodes is reported. The electrolyte used was a cyanide-stannate bath. The effects of cathode potential, mass transport (rotation rate of cylinder) and temperature were examined, as well as use of K+ in place of Na+ cations. It is shown that the silver deposition process is mass transport controlled, the tin activation controlled. There is no evidence to suggest that the various components of the bath interact with one another. The full range of Ag-Sn compositions can be formed as powders, and it appears that Cu in any proportion can be included in these powders. Powders having the composition of commercially available dental amalgam alloys (Ag-28% Sn, O-30% Cu) were prepared.