Electrochemical characteristics of Ti–6Al–4V alloy in 0.2 N NaCl solution

Tafel slopes of Ti–6Al–4V alloy in 0.2 N NaCl solution at the rate-determining (rd) interface in the quasi-passive potentiodynamic region have been determined by means of potentiostatic holds interrupted by short potentiodynamic tests every 10 min. The results show that the Tafel slopes increase with potential, and that the potential drop at the rd interface in the quasi-passive state increases with rising overpotential, and then decreases during a subsequent potentiostatic hold. The quasi-passive state is a dynamic equilibrium process between the film formation and the ion-transfer reaction at the rd interface. A model for the kinetics of the experimental potentiodynamic polarization is presented.