Phase transformations and electrochemical stability of TiO2 nanotubes films grows in beta metastable titanium alloysThursday (29.09.2016) 10:00 - 10:15 Part of:
Nanostructured titania (TiO2) has attracted attention in biomedical field for coating titanium implants because its capability of increase the cellular bioactivity and to favor the osseointegration. The nanostructured TiO2 as-prepared are amorphous, but shows phase transitions to anatase or rutile depending of annealing temperature. Others factors as dopants, NTs architecture and thermo-mechanical history substrate could modify it phase transition temperature. The objective of this study is to investigate the effects of doping and architecture NTs grows on beta titanium alloys Ti-Nb, Ti-Nb-Sn and Ti-Nb-Zr on TiO2 phase transformations and its electrochemical stability. Electrochemical anodization was performed using as electrolytes an aqueous solution 0.3% HF and an organic solution contained 0.3% NH4F/10%H2O in ethylene glycol for up to 2 h anodization time and 20 V electric potential. The amorphous nanostructured TiO2 samples were heat treatment at different temperatures (from 350 to 750 ºC) for 1 h and characterized by glancing angle x-ray diffraction (GAXRD) and field-emission scanning electron microscopy (FE-SEM). The electrochemical stability of TiO2 NTs samples were examined through impedance spectroscopy (EIS) in Ringer’s solution. Nanotube or nanowire features were observed on titanium alloys surface according electrolytes composition, aqueous or organic solutions, with subsequent heat treatment no shows great influence on architecture of TNs samples. Otherwise, the annealing promoted the formation of anatase and/or rutile phases in different proportion depending upon the annealing temperature and chemical composition substrate.