Electrochemical activation of passivated pure titanium in artificial seawater

As one of the most corrosion resistant metallic material, Ti or its alloy may find a variety of applications in the marine industry. It is important to understand the passivation mechanism of Ti in seawater. In this paper, the activation process of a passivated pure titanium TA2 in artificial seawater was investigated by means of potentiostat polarization, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The influence of seawater composition on the activation behavior was also studied. The result showed that the activation occurred around 1.6 V (SCE). Scanning electron microscope (SEM) and oxygen evolution monitoring indicated that obvious defects emerged on the surface of TA2 but no bubble was detected by applied potentials in the range of 1.4~1.6 V (SCE). According to Mott− Schottky analysis of the passivated and activated TA2 surface, the activation might be attributed to a transition of the semiconducting performance of the surface film on TA2.