Effect of tartrate salt concentration on the morphological characteristics and composition of Cu-Zn electroless plating on zamak 5 zinc alloy

This work reports the characterization of brass coatings deposited by an electroless process on zamak-5 alloy substrate. The results show that an increase in the tartrate salt concentration in the brass electroless bath promotes an increase in the copper deposition rate. It was observed that, in coatings with less concentrations of the tartrate salt, the Cu/Zn atomic ratio is always less than one, with a slight increase across the coating thickness. In coatings prepared from solutions with greater tartrate salt concentration, Zn deposits at higher rates at the beginning of the deposition, however after certain thickness, the Cu/Zn atomic ratio was greater than one. This change in composition affects the bulk and surface morphology of the deposited coatings, which were analyzed using a Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) and showed strong metallic Zn and weak CuZn5 (ε-phase) diffraction lines.