An improved electrochemical model for strain dependent electrochemical polarization and corrosion kinetics

Abstract

To systematically reveal the correspondence between surface properties and corrosion behaviors under mechanical conditions, an improved Butler-Volmer (IBV) electrochemical model is proposed by introducing the strain effects on electrochemical polarization through the scaled strain energy. Under mechanical straining, the three critical physical parameters i.e., surface energy, work function and strain energy, may be changed synergistically, which would consequently modify the exchange current density and equilibrium potential for the anode polarization curves. Taking two representative metals of Mg and Zn as a demonstration, it reveals that both tensile and compressive strain would contribute to the corrosion rate by lowering the activation energy barrier, in agreement with previous experimental observations. The improved model opens an alternative way to quantify the relationship between surface properties and corrosion behavior via intrinsic materials properties, which is beyond the normal design rules empirically based on either surface energy or work function alone.