Electrodeposition of Au-Sn alloys from alkaline baths

A bath for the electrodeposition of white gold alloys of interest for the electroforming of hollow jewellery is proposed. The investigated system is an alkaline KAu(CN)(2) bath for the electrodeposition of Au-Sn alloys. The electrochemical investigations are based on cyclic voltammetry and electrodeposition experiments. Electrodeposited foils were studied from the crystallographic, compositional and morphological points of view. Co-deposition of Au and Sn gives rise to the formation of a series of intermetallic phases, which can be detected by X-ray diffraction and anodic stripping. Deposits are typically polyphasic; the phase composition generally does not correspond to the equilibrium one. Chemical compositions ranging from high-Au to high-Sn can be obtained by galvanostatic deposition at suitable current densities.