In the present work, well ordered nanoporous anodic aluminum oxides (AAO) have been prepared on aluminum by a two step anodization process in 0.5 M oxalic acid at various potentials. We report the properties and semiconducting characteristics of the porous alumina barrier layers by electrochemical impedance spectroscopy analysis (EIS). EIS is considered to be a highly sensitive and non-destructive technique that allows determining barrier oxide layer characteristics. Aluminum oxide barrier is considered as a semiconductor which acts as a p-n heterojunction at anodizing voltages up to 20 V. The alumina barrier layer structure consists of a hole transport inner layer and an electron transport outer layer. Doping densities, flatband potential as well as space charge layer thickness are discussed in correlation with anodizing potential. Barrier layer thicknesses measurements obtained by EIS were compared with those obtained after EIS measurements by direct scanning electron microscopy observations.

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 compared to and . Corrosion test results in 0.5 M NaCl solution show that Cu–Zn deposit produced from chloride bath exhibited the highest corrosion resistance.

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