Mechanical and structural characterization of titanium nanotubes produced by anodic oxidation

Full text: Titanium is a biomaterial with high biocompatibility and low elastic modulus in comparison with other metals. For these reasons it is widely used on endosseous and orthopedic implant manufacturing. However, there is still a remarkable difference between the elastic modulus of titanium and the bone tissue, such contrast leads to a stress-shielding effect that could cause a loss of the metallic implant. In order to enhance the transition between the mechanical characteristics of the metallic implant and bone tissue it is possible to generate a layer which will make this change more gradual, in order to minimize the stress shielding effect. Thus, a self organized layer of titania nanotubes produced by anodization could help solve this issue. Then it is necessary to characterize the mechanical properties of the nanotubes and compare with same properties of the titanium substrate.To achieve these purposes nanotubes layers were produced using anodic oxidation under potentiostatic mode with different voltages. The morphology of the anodic film was investigated by Scanning Electron Microscopy (SEM), the atomic composition of the layer was characterized using the energy dispersive x-ray detector (EDS), the crystalline and molecular structures were characterized with X-ray diffraction (XRD) and Raman Spectroscopy respectively. The measurement of the elastic modulus was realized with the Nanoindentation technique. Preliminary results indicate that the nanotubes formed perpendicularly to Ti surfaces are self organized and its diameter depends on the applied voltage. Nanoindentation tests showed a reduction of the elastic modulus when compared with Ti substrate. References: [1] Yinchang Li, Qun Ma, Jun Han, Lili Ji, Junxia Wang, Jieyu Chen, Yongqian Wang. Applied Surface Science, Volume 297, 1 April 2014, Pages 103-108 [2] Besim Ben-Nissan, Andy H. Choi, Avi Bendavid. Surface and Coatings Technology, Volume 233, 25 October 2013, Pages 39-48. (author)