抄録
The co-deposition of a small amount of zinc impurity in the silver cyanide bath has been studied. A lavelled compound 65Zn(CN)2 was added to the bath in the concentration range of 0.05-1.0g/l. The amount of zinc co-deposited with silver increased with increasing zinc concentration, current density, and bath temperature. It was found that the amount of co-deposited zinc did not increase further after 1 min of plating time. This indicates that zinc deposited only in the initial stage of electrodeposition and the further co-deposition was prevented by the subsequent deposition of silver. The X-ray diffraction patterns of the silver deposits did not show any appreciable changes in orientation. Observations by electromicroscopy revealed coarse crystal grain growth and distinct nucleations. The autoradiography of the deposit showed that the co-deposition occurred obviously in polishing flaws on the surface at low zinc concentrations, but occurred around several spots at high zinc concentrations.
