Effect of surface finish on TiO_2 films obtained thermally as corrosion protection

摘要

The present work is a study of the effect of surface finish (grade 1000, 1200 and fine polishing to 3 μ) and of the corrosion resistence in films obtained by heat treatment (HT) an annealing at two different temperatures (700 and 800°C) in Ti6Al4V alloy. Corrosion behavior through the use of electrochemical techniques such as polarization curves (CP) and electrochemical impedance spectroscopy (EIS) in a Hank's saline solution was evaluated. In addition, the samples were characterized by Scanning Electron Microscopy (SEM) and microanalysis by Energy Dispersion X-ray Spectroscopy (EDS), in their arrival conditions (untreated) and after heat treatments (HT). The micro structural characterization revealed the presence of a biphasic micro structure a phase matrix α (rich in Al) with β (rich in V) distributed in the grain boundaries. The results of the electrochemical evaluation indicate decrease in the corrosion rate of the samples with HT at (700 and 800°C) with respect to the untreated samples.