The mechanism of Zn corrosion in both aerated and deaerated aqueous KNO₃ solutions

Abstract

The corrosion of Zn in both aerated by air (O₂ + N₂), and deaerated by N₂, solutions of KNO₃ at concentrations largely varying, 10^‐5‐1 M, is studied. The corrosion process is followed in time by potentiometry and the potential of Zn electrode (vs. calomel) vs. time plots is derived. In both cases, a transition period is observed until a steady state is achieved where the rate of Zn²⁺ and OH^‐ production becomes equal to the rate of Zn(OH)₂ precipitate formation. In the aerated solutions the potential and corrosion rate decrease with time while in the deaerated solutions they pass successively through a minimum and a maximum before a steady state is achieved. By a suitable potentiometric analysis the results are explained. The most important factors found to be affecting the mechanism of corrosion process are presented. From the discovery of the mechanism and the factors affecting the Zn corrosion, predictions for promoting or slowing down the corrosion process may be derived.

Citation

Roubani‐Kalantzopoulou, F., Patermarakis, G. and Karayianni, H. (1998), "The mechanism of Zn corrosion in both aerated and deaerated aqueous KNO₃ solutions", Anti-Corrosion Methods and Materials, Vol. 45 No. 2, pp. 84-94. https://doi.org/10.1108/00035599810368517