Electrochemical corrosion behavior of Ti-24Nb-4Zr-8Sn alloy in a simulated physiological environment

Electrochemical corrosion behavior of a biomedical titanium alloy Ti-24Nb-4Zr-8Sn in weight percent was investigated in a phosphate buffered saline solution at 37 degrees C utilizing open-circuit potential, potentio-dynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Both commercially pure titanium and Ti-6Al-4V alloy were also investigated to make a comparison. The results show that all the samples were spontaneously passivated once immersion into the electrolyte. Ti-24Nb-4Zr-8Sn alloy exhibited a much wider passive region compared with pure titanium and Ti-6Al-4V and also relatively low corrosion current density which is comparable to that of pure titanium in the buffered saline solution, which was attributed to a stable passive film mainly consisted of titanium oxide and niobium oxide on its surface. The EIS results indicated the presence of a single passive layer with thickness similar to 2 nm for Ti-24Nb-4Zr-8Sn and pure titanium but a duplex film consisting an inner barrier layer and an outer porous layer on Ti-6Al-4V alloy with thickness of similar to 3 nm and similar to 2.5 nm, respectively. (C) 2011 Elsevier B.V. All rights reserved.