The role of passive potential in ultrasonic cavitation erosion of titanium in 1 M HCl solution.

The influence of the applied passive potential on the ultrasonic cavitation erosion of Ti specimen in 1 M HCl solution was investigated by mass loss experiment, scanning electron microscopy (SEM), electrochemical impedance spectra (EIS) and Mott-Schottky plot. The results showed that Ti was in the passive state within the potential region from -0.3 VSCE to 1.5 VSCE under ultrasonic cavitation erosion. The applied passive potential can obviously decrease the mass loss of Ti caused by ultrasonic cavitation erosion in 1 M HCl solution. The resistance of the passive film increased, the flat band potential moved to positive direction, and the donor density of the passive film decreased with increasing the passive potential. Finally, a physical model was provided to explain the experimental results based on energy band and semi-conductive theories.