Effect of Anodization Times on Preparation of Porous Anodic Aluminium Oxide

Porous anodic aluminum oxide(AAO) film was prepared on highly pure aluminum foil in an oxalic acid electrolyte of 0.3 mol/L concentration at 8 ℃ by applying a DC voltage of 40 V and two-step anodization.The surface patterns of the porous AAO films prepared by single and double anodizations were characterized by means of FESEM.The phase structures of both raw aluminum foil and the AAO film were characterized by using XRD and the permeability of pore-expanded AAO film was observed under TEM.The results show that the AAO film prepared by double anodization offers more regular and ordered structure and thicker relative to that prepared by single anodization,substantially being an amorphous Al2O3. KEY WRODS:single anodization;double anodization;porous anodic aluminium oxide film