EFFECT OF ANODIZING CONDITIONS AND ULTRAVIOLET IRRADIATION ON HYDROPHILICITY OF ANODIZED FILMS ON Ti-6Al-4V

Abstract

The anodized films on Ti-6Al-4V alloy are normally formed by anodization process at high current densities or voltages. This film formation technique has been widely used to improve the hydrophilicity of the film for dental implant applications. Our attempt is exploring whether anodized films with proper hydrophilicity can be performed by anodization at low current densities or voltages. The anodized films on Ti-6Al-4V were prepared by both of galvanostatic and potentiostatic method in either 1M H3PO4 or 1M MCPM (Ca(H2PO4)2•H2O) with current densities 0.25-2 mA/cm2 or applied voltage 2-10 V for 30 min. The hydrophilicity was improved on the anodized films formed at low current density of 2 mA/cm2 in 1M H3PO4 and 1 mA/cm2 in 1M MCPM and low voltage of 6 V in both electrolytes, consequently subjected to UV irradiation for various times up to 24 h. After UV irradiation the contact angles of films significantly decreased however the surface morphology did not change. FTIR spectra confirmed that -OH groups around 3,000-3,600 cm-1 disappeared. It is indicated that –OH group was not stable under UV irradiation. XPS spectra investigated that the peak intensities of Ti 2p and O 1s increased, while C 1s peak decreased. However, the binding energy shown in XPS spectra did not change. It is indicated that these anodized films were not TiO2 but it might be hydroxylated TiOx.