The Role of Carbon Dioxide in the Atmospheric Corrosion of Zinc: A Laboratory Study

We report on a laboratory study of the atmospheric corrosion of zinc in air containing different concentrations of carbon dioxide (<1, 350, 1000, and 40,000 ppm ). The samples were exposed to synthetic atmospheres with careful control of concentration, sulfur dioxide concentration, relative humidity, and flow conditions. The relative humidity was 95%. Mass gain and metal loss results are reported. The corrosion products were analyzed quantitatively and qualitatively by a combination of grazing‐angle x‐ray diffraction, scanning electron microscopy, gravimetry, and quantitative analysis for carbonate. The corrosion rate of zinc increased with increasing concentration. In the presence of carbon dioxide formed. Hydrozincite, was only identified after exposure to high concentration. Zinc hydroxycarbonate was converted into hydroxysulfate exposed to air containing 225 ppb . was produced in all exposures including . The zinc hydroxycarbonate surface film formed in the presence of was not protective in humid polluted air.