Chiang Mai Journal of Science

 The objective of this study was to investigate the corrosion behavior of titanium alloy after anodization. Ti-6Al-4V alloy specimens were anodized in a 0.5 M phosphoric acid solution for 30 minutes using constant voltages of 100, 150, 200 and 300 volt. After anodization, the surface morphology, surface roughness, and crystal structure were observed under scanning electron microscopy (SEM), scanning probe microscopy (SPM), and x-ray diffraction (XRD), respectively. To determine the corrosion behavior of as-received or anodized Ti-6Al-4V alloy, all specimens were investigated using a potentiodynamic polarization technique in a 0.9% saline solution at 37^oC. The results indicated that the E_corr of the as-received material was statistically lower than that of the anodized groups. The E_corr of anodized Ti-6Al-4V alloy increased as the voltage of anodization increased. There was no significant difference in corrosion rates between the as-received material and Ti-6Al-4V alloy specimens anodized using 100 or 150 V. Titanium alloy anodized using 300 V had the highest mean corrosion rate. It can be concluded that anodization can improve the corrosion potential of Ti-6Al-4V alloy, but increased voltage in the anodization of Ti-6Al-4V alloy led to an increased corrosion rate implying that higher voltage does not provide good corrosion resistance with Ti-6Al-4V alloy. The appropriate applied anodization voltage is necessary to generate the optimum titanium surface.