Comparative study of Cu-Zn coatings electrodeposited from sulphate and chloride baths.

ABSTRACT

In this work, the effect of the nature of the salt anion (chloride and sulphate) in the Cu-Zn citrate bath was investigated, using cyclic voltammetry (CV) and chronoamperometry (CA). Experimental electrodeposition parameters (switching potential and imposed potential) were varied in order to examine their influence on the deposits. The coating microstructures were observed by scanning electron microscope (SEM-EDS), the coating phases were characterized by X-ray diffraction (XRD) analysis and the surface composition was assessed by XPS. Higher current efficiency was obtained in chloride baths compared to sulphate baths and best deposits were obtained at - 1.4 V v s . ( A g / A g C l / K C l ) compared to - 1.2 and - 1.5 V v s . ( A g / A g C l / K C l ) . Corrosion test results in 0.5 M NaCl solution show that Cu-Zn deposit produced from chloride bath exhibited the highest corrosion resistance.