Mechanism of Bone-like Apatite Formation on Anodised Titanium under UV Irradiation

Abstract

— Anodic oxidation is an electrochemical method for the production of ceramic films on a metallic substrate. It had been widely used to deposit the ceramic coatings on the metals surface. UV light was used to accelerate the bone-like apatite formation on the anodised titanium in this study. The processing was composed of two steps which were UV light treatment after anodic oxidation, and UV light illumination during simulated body fluid (SBF). This study aims to study the mechanism of bone-like apatite formation on the surface of anodised titanium under UV irradiation. High purity titanium foils were anodised at 350 V, 70 mA.cm -2 in electrolytic solution containing glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA) for 10 minutes. UV light treatment was conducted in pH-adjusted distilled water (pH 1) for 12 hours. Next, SBF was carried out by illuminating with UV lamp for 1 week. Anodised titanium foils were characterised by using field emission scanning electron microscopy (FESEM) and fourier transform infrared spectroscopy (FTIR). The results showed that bone-like apatite started to form at concave surface due to the presence of nucleation site. The surface of anodised titanium was fully covered by bone-like apatite after soaking in SBF for 4 days. Denser bone-like apatite was formed after 7 days immersion in SBF. The mechanism of the growth of bone-like apatite was illustrated. The FTIR results showed that carbonated bone-like apatite was formed on the surface on anodised titanium. The result indicated that the anodised titanium in mixture of β-GP + CA possess excellent apatite-forming ability under UV irradiation.