Ti-based alloys as porous materials with low elastic modulus has been recently developed due to the evident need to avoid the stress shielding problems related to stiffness mismatch related to human bone. In this work, Ti-30Nb-13Ta-2Mn alloy as porous material was obtained by powder metallurgy using (NH₄)₂(CO₃) as space-holder. Powders and space-holder were mixed together and compacted with 400 MPa stress. (NH₄)₂(CO₃) particles were removed from the compacts during sintering at 1250 °C for 3 h in Ar atmosphere. The porosity and active area of the porous electrode were estimated by using Archimedes methods and BET analysis. In addition, the surface analysis was carried out by SEM and XRD. Finally, electrochemical measurements such as open circuit potential curves, polarization curves and electrochemical impedance spectroscopy were carried out in a simulated blood plasma fluid called Ringer’s solution at 37 ºC. Results revealed foams with heterogeneous pore distribution in diameter as well as length. The electrochemical results showed that the corrosion potential was shifted to more negative values and the anodic and cathodic current were increased as a function of exposure time. On the other hand, impedance analysis displayed an impedance of the de Levie associated to the anodic response in parallel with an interfacial impedance attributed to cathodic response. Additionally, an evolution of the passive oxide layer as a function of exposure time was observed, which was mainly formed at the pore walls and, the cathodic reaction related to the oxygen reduction reaction took place mainly outside the pore.

Reference

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