Tribo-electrochemical impedance: A new technique for mechanistic study in tribocorrosion

• A new approach using a sine-wave modulation of the velocity of rotation of a pin-on-disc tribometer is presented.
• The general mathematical background of this new modulation technique is derived.
• The kinetics of film healing can be extracted from the complex transfer function current/rotation speed.
• Experiments on the repassivation of 316L stainless steel were performed and discussed.

On the basis of a classical model of triboelectrochemistry, a new approach is proposed based on an impedance ratio of a mechanical perturbation and an electrochemical response. Theoretical derivation, experimental setup and application to a passive stainless steel in a borate solution are presented. Transient characteristics yielded by the technique, associated to a permanent tribological regime, are found to obey a two-time-constant law. They are discussed and compared to the global repassivation transients of the material after switching off the abrasive friction.

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