Effect of anodization time on morphology and electrochemical impedance of andic oxide films on titanium alloy in tartrate solution

The present study investigated the effect of anodization time on the anodic oxide films formed on titanium alloy Ti-6Al-2Zr-1Mo-1V. The morphology, surface roughness, crystal structure, and electrochemical impedance of the anodic oxide films were studied by using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), respectively. At the beginning of the anodization, a compact inner layer was form on the substrate. With elongated anodization time, the inner layer ruptured locally and secondary oxide particles grew up. Finally, the secondary oxide particles aggregated in masses forming outer layer of anodic oxide films. The surface roughness of the oxide films increased firstly and then decreased. These results showed good correlation to the analysis of EIS. The results of Raman spectroscopy showed that the relative intensity of anatase and rutile had a tendency to increase with anodization time.