A Laboratory Study of the Effect of Ozone, Nitrogen Dioxide, and Sulfur Dioxide on the Atmospheric Corrosion of Zinc

We report on a laboratory study of the role of O 3 , NO 2 , and SO 2 in the sub‐parts per‐million range on the atmospheric corrosion of zinc. Each sample was exposed individually to synthetic atmospheres with careful control of pollutant concentrations, relative humidity, and flow conditions. In addition, we studied the interaction of the pollutants with zinc using time‐resolved trace‐gas analysis. NO 2 and O 3 accelerate the corrosion of zinc in humid air containing SO 2 . O 3 oxidizes loosely bound four‐valent sulfur on the zinc surface to sulfate while NO 2 catalyzes the oxidation of SO 2 on zinc. The increased formation of sulfate and hydrogen ions on the surface leads to the dissolution of solid corrosion products and to an increased rate of metal dissolution. The acceleration of SO 2 oxidation and deposition on zinc by O 3 becomes increasingly important as the concentration of SO 2 and O 3 decreases. The results suggest that O 3 and NO 2 may be important factors in the atmospheric corrosion of zinc.