Enhancing surface characteristics of Ti–6Al–4V for bio-implants using integrated anodization and thermal oxidation

Abstract

Modifications of Ti–6Al–4V surface roughness, wettability and composition are increasingly studied to improve cellular viability on biomedical implants involving Ti–6Al–4V. In this study, it is shown that modification of Ti–6Al–4V samples using anodization (for the formation of titania nanotubes) combined with thermal oxidation (TO) results in superior surface characteristics to those of a smooth, rough, anodized-smooth or anodized-rough surface alone. Surface characterization is performed using water contact angle (WCA) measurements, white-light interferometry, Fourier transform infrared spectroscopy (FTIRS), field emission scanning electron microscopy and grazing incidence X-ray diffraction (GIXRD). WCA measurements before TO indicate that anodized-smooth and anodized-rough samples are super-hydrophilic (WCA less than 5°); WCA of non-anodized smooth and rough surfaces are 57 ± 6° and 86 ± 7°, respectively. After TO at 450 °C for 3 hours, all samples become super-hydrophilic; however, three weeks after TO, smooth and rough surfaces become hydrophobic, while anodized-smooth and anodized-rough surfaces remain hydrophilic. FTIRS and GIXRD data show that the TO of anodized and non-anodized smooth samples results in anatase and rutile TiO₂, of which anatase is favorable for cellular attachment. Micro-/nano-scale roughness and TO are discussed in the context of enhanced Ti–6Al–4V surface characteristics for improved cellular response.