The relevance of cathode kinetics to the interpretation of triboelectrochemical corrosion

Cathode properties were shown to indirectly impact the magnitude of the anodic current density, ia, of the wear track under reciprocating wear. The direct measurement of ia for CoCrMo, Zircaloy and Ti tribocorrosion was conducted on surface insulated samples by using novel techniques such as hetero-cathode tribocorrosion (HCT) and insulated electrode triboelectrochemistry (IET) under applied potential. The ia measured for the above systems exhibited a strong correlation with potential, which was different in each system. The variation of ia with time during sliding experiments at OCP, understood to affect the wear rates (i.e. Wear Accelerated Corrosion) observed under tribocorrosion, was experimentally quantified and proven to be linked to the cathode properties. Marked deviations in OCP behavior were recorded by changing the cathodes utilized and the subsequent cathode effect on the wear mechanism was demonstrated via HCT experiments by substituting different size hetero-cathodes. Data derived from IET and HCT also resulted in the predictive numerical modeling of several tribocorrosion experiments performed on CoCrMo and Zircaloy, by accurately accounting for the interdependencies between cathode kinetics, ia and the OCP.