Effect of Soil Moisture on Corrosion Behavior of Zinc in Simulated Soil Environment

Abstract

Corrosion of zinc in simulated soil at various degrees of saturation S_r was investigated by performing surface observations, corrosion depth analyses, electrochemical impedance spectroscopy, and potentiodynamic polarization tests. The aim was to evaluate the effects of soil moisture on the corrosion morphology and corrosion rate of zinc. At a high soil moisture content (S_r > 80%), the mean zinc corrosion rate was low and varied little as S_r varied. However, at a low moisture content (S_r < 80%), the mean corrosion rate increased markedly as the moisture content decreased and reached a maximum at S_r ~ 50%. The zinc corrosion morphology became more heterogeneous, indicating that the corrosion depth increased, as S_r decreased. The effects of soil moisture on the zinc corrosion morphology and rate were assessed from changes in oxygen reduction (cathodic reaction) and zinc dissolution (anodic reaction) in simulated soil.