Influence of Anodizing Parameters on Pore Diameter of Anodic Aluminium Oxide (AAO) Films Using Taguchi Design

Nanoporous anodic aluminium oxide (AAO) films were fabricated by using a two-step anodizing process of aluminium foils in oxalic acid electrolyte. The effect of synthesis conditions including applied voltage, electrolyte concentration and temperature on the pore diameter of AAO films was investigated. To reduce the number of experiments, the Taguchi L9 orthogonal array was adopted and the results were analyzed using minitab15 software. It was found that the pore size increased in direct proportion with the applied voltage. The proportion of the pore size with increasing electrolyte concentration was at first direct and then inverse and the maximum pore diameter was obtained in the case of 0.3 M. The pore size relation with increasing electrolyte temperature was at first inverse and then direct and the minimum pore diameter was seen at 10 ◦C. The diameter of the nanopores were predicted with the software in the range of 35–71 nm in different conditions of selected experimental parameters. Also, as a practical application of obtained AAO films, template-synthesis fabrication of polypyrrole nanowire arrays by electrochemical polymerization of pyrrole within the pores of the obtained AAO was successfully demonstrated.