ELECTROPLATING OF Cu-Sn ALLOYS AND COMPOSITIONALLY MODULATED MULTILAYERS OF Cu-Sn-Zn-Ni ALLOYS ON MILD STEEL SUBSTRATE by HARIYANTI

Two series of electroplating experiments have been carried out onto mild steel substrate at 65 °C in several electroplating baths under different constant applied current densities. The objectives of the first series of experiments are to understand the behavior of electrodeposition of Cu and Sn in the several alkaline cyanide baths and to explore the electroplating conditions which are appropriate for fabricating binary Yellow and White Miralloys coatings. The second series of experiments deals with an experimental study on electroplating of Compositionally Modulated Multilayer (CMM) consisting of multiple alternate nano-layers of quaternary Yellow and White Miralloys using dual bath technique (DBT). The kinetics and electrodeposition behavior of Cu-Sn alloys have been assessed by measuring their cathodic polarization behavior in selected electroplating baths. The influence of bath composition combined with current density to the compositions and properties of binary Cu-Sn and quarternary Cu-Sn-ZnNi alloys coatings deposited onto mild steel substrate have been studied in several electroplating baths. The uniformity of the coatings developed in this experiment is examined under FE-SEM, while the compositional uniformity of coating and phases present in the coating are assessed by EDX and XRD respectively. Dense, adherent, smooth and uniform binary Cu-Sn and quaternary Cu-Sn-Zn-Ni alloys coatings especially Yellow and White Miralloys, can be deposited with relatively high deposition rate. Introducing zinc and nickel into the coating does not significantly alter their chemical and mechanical properties. Formation CMM coatings has significantly increased the micro-hardness of the coatings. However, fabrication of multilayer coatings with individual layer thickness < 300 nm are essential. The relationship between the bilayers thickness (d,(μm)) and coating micro hardness (HV) has been