In Situ Impedance Spectroscopy Study Of The Electrochemical Corrosion Of Orthopedic Ti-6Al–7Nb In Simulated Body Fluid

The corrosion resistance of titanium alloy, Ti–6Al–7Nb, was investigated through electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) measurements and scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. The tests were done in Hank's solution at 37 o C for immersion periods expanded to 169 h. A high corrosion resistance was obtained for Ti–6Al–7Nb alloy in hank's solution due to the stable passive film formed on its surface. The EIS results indicated the presence of a single passive layer immediately after immersion. However, after 24 h of immersion in hank's solution, the EIS exhibited the presence of a bi-layered surface corresponding to an inner layer and an outer layer. Further, the film formed on the alloy after 169 h was confirmed by SEM and EDX analysis as calcium and phosphate may be due to apatite formation.