Microstructural characterization of Cu-Sn-Zn electrodeposits produced potentiostatically from acid baths based on trisodium nitrilotriacetic

Abstract This study characterizes the Cu-Sn-Zn electrodeposits produced potentiostatically from baths containing different concentrations of Cu 2+ , Sn 2+ and Zn 2+ ions and 0.60 M trisodium nitrilotriacetic (NTA) at pH 4.99 (higher stability). Ternary electrodeposits were produced onto AISI 1010 steel substrate at electrodeposition potential of −1.60 V with electrodeposition charge density of 3.0 Ccm −2 . Chemical composition of electrodeposits varied significantly, presenting higher Cu content (at.%) than that of other elements. Furthermore, it was verified that the high concentration of Sn 2+ ions in the baths hindered the reduction of Zn 2+ ions, leading to Zn-poor electrodeposits. Microstructure was generally composed of irregular crystallites and clusters of crystallites or dendrites dispersed on the surface, depending on chemical composition. X-ray diffraction showed formation of the ternary alloy by mixture of the Cu 5 Zn 8 , η-Cu 6 Sn 5 and Sn pure phases. In addition, electrodeposits with lower Cu content (at.%) also showed the SnO phase. Surface topography of the electrodeposits presented a rough aspect, with arithmetic roughness varying from 1.83 to 3.90 μm for electrodeposits with lower and higher Sn content (at.%), respectively. Adhesion tests indicated that the highest and lowest adherence percentages to the steel substrate were observed for the electrodeposits with the largest Zn and Sn contents (at.%), respectively.