The Atmospheric Corrosion of Zinc in the Presence of NaCl The Influence of Carbon Dioxide and Temperature

The atmospheric corrosion of zinc has been studied at 4, 22, and 38°C. The samples were exposed to synthetic air with careful control of concentration, relative humidity, and flow conditions. The relative humidity was 95%, and the concentrations of were <1 and 350 ppm, respectively. Sodium chloride was added before the exposures (0, 14, and ). Mass gain and metal loss results are reported. As expected, NaCl is corrosive toward zinc, giving rise to heavy pitting. In the absence of , the rate of the NaCl‐induced corrosion was found to increase strongly with temperature. However, in the presence of , the corrosion rate of zinc is independent of temperature. In the absence of , zincite, ZnO, is the dominant corrosion product, while zinc hydroxy carbonates and simonkolleite, , dominate in the presence of . A mechanism is presented that explains the observations. © 2000 The Electrochemical Society. All rights reserved.