Titania Nanotubes On Tianium Surfaces And The Ti-TiO₂-HA Coatings

Titanium was used extensively in orthopedic implants as its excellent biocompatibility and mechanical property.The surface modifications of titanium have attracted a lot of researcher's attention in order to improve the biological property of the titanium.In this study,the nanostructured titanium surface has been acquired through the anodic oxidation methods in HF-H2O solution with the active agent H3PO4. The thin films with various micromorphology and crystal structures have been fabricated by adjusting the voltage,anodic times and heat treatment.The properties of these films(surface hardness,Young's modulus,surface energy,corrosion resistance) have been evaluated through the experimental methods.Then the Ca-P salts have been deposited on the nanostructured titanium surface by electrochemical deposition method to acquire the Ti- TiO2-HA composite.Continuous and dense TiO2 nanotubes perpendicular to the Ti surface can be fabricated through electrochemical anodization methods.The diameters of the TiO2 nanotubes could varied from 50-120nm through changing the voltage,it could be expanded to 250 nm through the two-time anodic oxidation.The oxide film thickness distributed from 500nm to 2000nm through changing the anodic oxidation time. X-rays diffraction test indicated that the anodic oxidation film was amorphous TiO2,and transformed to anatase after 450 C heat treatment or rutile after 700 C heat treatment.SEM test indicated that the structure of TiO2 nanotubes had not been destroyed by heat treatment.Contact angle test indicated that the contact angles decreased as increase of the nanotube diameter;while the surface energy increased.Surface energy of TiO2 nanotubes increased after 450 C heat treatment compared to the pure titanium.The Young's modules and the hardness of the samples decreased obviously after the anodic oxidation.The corrosion resistance could be improved by anodic oxidation and heat treatment.It increased while the nanotube's diameter enlarged.Ca-P coatings with thickness of about 15 m could be obtained by electrochemical deposition at constant voltage and alkali heat treatment.The coating was mainly composed of HA indicated by EDS and XRD test.The binding strength between the coating and substrate is about 15MPa which meets the requirement of the practical application.Compare to pure titanium.Ti-TiO2-HA mutilayer coating owns corrosion resistance,low surface hardness and low Young's modulus. It also owns the good biocompatibility due to the existence of HA. Thus,it would be a kind of orthopedic implant material in application prospect.