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 CO 2 concentration, relative humidity, and flow conditions. The relative humidity was 95%, and the concentrations of CO 2 were <1 and 350 ppm, respectively. Sodium chloride was added before the exposures (0, 14, and 70 μ g / cm 2 ). Mass gain and metal loss results are reported. As expected, NaCl is corrosive toward zinc, giving rise to heavy pitting. In the absence of CO 2 , the rate of the NaCl‐induced corrosion was found to increase strongly with temperature. However, in the presence of CO 2 , the corrosion rate of zinc is independent of temperature. In the absence of CO 2 , zincite, ZnO, is the dominant corrosion product, while zinc hydroxy carbonates and simonkolleite, Zn 5 ( OH ) 8 Cl 2 · H 2 O , dominate in the presence of CO 2 . A mechanism is presented that explains the observations.
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Lindström et al. (2000) studied this question.