Effect of duty cycle on the crystallinity, pore size, surface roughness and corrosion resistance of the anodized surface on titanium

• Novel anodization method that can form a crystalline titanium dioxide while maintaining a homogenous macroscopic color.
• Nanosized surface roughness and porosity were shown for anodized samples.
• Lower duty cycle anodized samples were found to have greater amount of anatase and rutile.
• Lower duty cycle anodized samples showed higher corrosion resistance in Ringer's solution at 37 °C.

Titanium is one of the most commonly utilized metals for the manufacture of orthopedic and dental implants. The purpose of the present research was to investigate the effect of anodization duty cycle (2%–100%) using a pulsed potentiostatic waveform on the formation of crystalline titanium dioxide (anatase and rutile), surface features, and corrosion resistance while maintaining a homogenous oxide color. Based on the results of a previous study, specimens with gold and dark green colors were chosen as evaluation points in the present study. While both the gold and dark green anodized surfaces produced with the pulsed potentiostatic waveform contained anatase, significantly greater anatase levels were shown to be present on the dark green colored oxide specimens. Furthermore, rutile formation was shown only for the dark green specimens. Both the gold and dark green specimens were found to have nano-rough surfaces. The results of this study suggest that the dark green specimens produced with a lower duty cycle exhibited a thicker oxide, a higher degree of crystallinity, a homogenous nano-pore size and distribution, and a more corrosion resistant passive oxide layer.