Morphology of anodic alumina films obtained by hard anodization: Influence of the rate of anodization voltage increase

Abstract

The influence of the anodization voltage ramp on the morphology and thickness homogeneity of porous anodic alumina films was studied. The samples were prepared in the oxalic acid at 120 V during the hard anodization process. As a nondestructive characterization method, the smallangle Xray scattering technique was used. The analysis of diffraction patterns allows determining the mean value and dispersion of interpore distance and the channel tortuosity with high accuracy. The increase of voltage ramp at the initial stage of hard anodization process was shown to lead to reduction of mechanical deformation (tortuosity) of anodic alumina film during crystallization.