Electrochemical Behavior of Ti-6Al-7Nb in Simulated Physiological Body Fluid Environment

Abstract

The electrochemical behavior of Ti-6Al-7Nb was investigated, and compared with that of Ti–6Al–4V alloy, which is commonly used as implant material, particularly for dentistry, orthopaedic and osteosynthesis applications. The aim of present study was to evaluate their corrosion resistance in an artificial physiological conditions using Hank’s solution at 37◦C. This evaluation was carried out through the analysis of the potentiodynamic polarization (PD), and electrochemical impedance spectroscopy (EIS) tests. Very low current densities were obtained from the PD curves, indicating a typical passive behavior for two investigated alloys. The EIS results at open circuit potential and at different potential exhibited capacitive behavior (high corrosion resistance) with phase angles close to −90◦ and high impedance values at low and medium frequencies, which are indicative of the formation of a highly stable film on these alloys in the test solution. The resistance of TAN is slightly higher than that of TAV. This difference can be attributed to the alloying elements. For TAN, the formation of Nb2O5 oxide, which is chemically more stable and less soluble compared to V2O5 formed on the Ti–6Al–4V alloy, enhances resistance to dissolution of the surface film. Thus, it has been suggested that Ti–6Al–7Nb can be a better alternative to Ti–6Al–4V in simulated body fluid environment.