Modelling the evolution of electrochemical current in potentiostatic condition using an asperity-scale model of tribocorrosion

In this paper, an asperity-scale electrochemical model is combined with a computational contact mechanics solution to simulate a tribocorrosion system. The proposed approach is unique, considering the real-time evolution of surface topography, wear and corrosion. The proposed framework facilitates the prediction of wear, corrosion and its synergies by de-coupling wear and corrosion processes; better representing the physical and chemical system. The model is able to determine the current on the micro scale and the summation of the asperity currents is assumed to define the macro-scale quantity of the current. The evolution of current from this model has been validated with experiments using a ball-on-plate tribometer. The findings are in very good agreement with the experiments. The numerical model directly calculates the real area of contact in a tribo-corrosive condition and highlights its importance in the electrochemical and mechanical wear. Investigating the effect of load also confirms that if the topography is evolved at different loading conditions, the electrochemical response of the system also evolves accordingly. After the model validation, the effect of mechanical wear on the corrosive wear has been computed and it suggests that the corrosive wear changes linearly with the mechanical wear.