Corrosion of a Zinc Rotating Disk in One Molar Hydrochloric Acid

摘要

The corrosion of a zinc rotating disk in one molar hydrochloric acid has been studied using a potentiodynamic polarization method. Experimental rotating-disk data at a rotation speed of 1600 rpm are presented. The polarization curves are analyzed to determine the transfer coefficients and rate constants for the anodic zinc dissolution and cathodic hydrogen evolution reactions. A modified Butler-Volmer equation is used to describe the kinetics of the zinc and hydrogen charge-transfer reactions accounting for the forward and back terms of each reaction. Mass transfer of the electroactive and complexed zinc species is accounted for assuming that the homogeneous reactions are in equilibrium. The experimental polarization curve shows good agreement with that predicted theoretically provided the back reactions are neglected. However, when the modified Butler-Volmer equation is used, the cathodic polarization sweep away from the open-circuit potential is significantly different from what was expected owing to the effect of the cathodic zinc reaction. Results of the model are compared to conventional polarization techniques which underestimate the corrosion-current density. (ERA citation 09:040534)