In Situ Observation of Friction-Induced Electrochemical Reactions and Impedance in Tantalum ECMP

The electrochemical and tribological performance of tantalum was studied using a specially assembled test system. This system is able to carry out electrochemical-mechanical polishing (ECMP). Through the measurement of potentiodynamic and electrochemical impedance spectroscopy, results showed that the corrosion current increased with the increase of mechanical parameters such as down force and the rotating speed. Further analysis found that the tantalum surface was passivated during ECMP. The polarization resistance R-p of the surface oxide film was influenced by the polishing parameters. The surface electrochemistry was apparently associated with friction. The present research demonstrated an effective methodology to observe friction and electrochemical properties of the tantalum simultaneously. Being able to pinpoint the reactions of mechanical vs electrochemical is beneficial to understanding ECMP and will lead to its process optimization.