Study On The Self-organized TiO₂ Nanotubes On Ti And Ti-Ta Alloy

The TiO₂ nanotubes f abricated by self-organized a nodization pos sess greater internal surface area and absorption capacity. Its unique porous structure can not only allow the growth in of bone tissue, showing special advantages in biomedical field, but a lso greatly impr ove t he opt ical and catalytic pr operties of TiO₂ nanotubes. Particular TiO₂ nanotubes s tructure w as formed on T i a nd Ti-Ta a lloys b y electrochemical self-organized anodization i n t his paper. The i nfluence o n nanotube growth and microstrcture of different parameters, such as anodization potential, time, temperature of electrolyte, was investigated. The growth mechanisms of uniform and two-size s cale na notubes w ere al so discussed. X-ray P hotoelectron S pectroscopy (XPS), Transmission E lectron M icroscopy ( TEM), Scanning E lectron Microscopy (SEM), X-ray di ffraction (XRD) w ere i ntroduced to characterize and analysis the nanotubes. The results showed that:The Ti O₂ nanotubes c an be f ormed i n Ti and Ti-Ta al loy b y self-organized anodization, its morphology becomes finer as the increased Ta content and reaches the optimum uniform and orderly at 50% Ta. The nanotube length will increase with the increased a nodization p otential a nd t ime,temperature, While the diameter of nanotubes will increase with the increased anodization potential and water content in the electrolyte. The diameter is essentially determined by the biggest current density during the anodization, while the length is determined by the whole current density.The key factor leading the formation of two size-scale nanotubes on Ti-50Ta is water content in the electrolyte, also it would be influenced by anodization potential and t ime. The na notubes s plit r esulted b y une ven di stribution of e lements i n t he oxidation process leads to the formation of two size-scale nanotubes The as-formed nanotube l ayer i s a morphous i n na ture a nd c an be c rystallized unde r di fferent annealing process andβ-Ta₂O₅ phases showed up after annealing at 750℃for Ti-Ta alloy.