Formation and characterization of anodized layers on CP Ti and Ti-6Al-4V biomaterials

The biocompatibility of titanium and Ti-6Al-4V alloy materials has been attributed to the presence of a passive surface oxide layer. In this investigation, the feasibility of creating a thick, porous oxide layer by anodizing commercially pure Ti and the titanium alloy in sulfuric acid under potentiostatic conditions was examined. Characterization of the anodic oxide layers was carried out to determine their thickness, morphology and composition. The thickness of the oxide layers, as determined by Rutherford backscattering spectrometry, was found to be a function of applied potential, anodizing time and electrolyte temperature. Scanning electron microscopy investigations revealed that under suitably controlled experimental conditions, a very porous (10 μm diameter pores) surface layer could be formed. Incorporation of sulfate ions into the oxide layer was evident from depth profile analysis by Auger electron spectroscopy. The isoelectric point of the oxide layer formed on the alloy surface was measured to be 5.8.