Effect of water content on ionic current, electronic current, and nanotube morphology in Ti anodizing process

摘要

The relationships between porous morphology and anodizing parameters, including anodizing voltage and current and water content, cannot be successfully explained. A decomposition approach of the anodizing current is proposed to overcome this challenge. The anodizing processes of Ti foils in NH4F/ethylene glycol solutions with different water contents (0, 2, 5, and 10 vol%) were investigated by analyzing the anodizing current-time curves. The measured current-time curves were fitted with a theoretical formula to obtain the corresponding fitting equations by mathematical software. The fitted curves drawn according to the fitting equations essentially coincided with the measured ones. The fitted curves were separated into two parts: ionic current-time and electronic current-time curves. The complicated surface porosities and the different lengths of nanotubes could be successfully explained by the electronic current and the ionic current.