||Laboratory Investigations of the Impact of Dry Deposition of SO2 and Wet Deposition of Acidic Species on the Atmospheric Corrosion of Galvanized Steel.
Edney, E. O. ;
Stiles, D. C. ;
Spence, J. W. ;
Haynie, F. H. ;
Wilson, W. E. ;
||Northrop Services, Inc., Research Triangle Park, NC.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Sciences Research Lab.
Galvanized materials ;
Atmospheric corrosion ;
Sulphur dioxide ;
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A series of short-term laboratory experiments were conducted in which galvanized steel samples were exposed to sub-ppm levels of SOsub 2. Dew was produced periodically on the test panels, and, at the end of some experiments, panels were sprayed with solutions of various pH levels. Both dew and rain rinse samples were analyzed for SO3(=), SO4(=), and Zn. The laboratory results suggest that the damage to galvanized steel induced by the dry deposition of SO2 can be calculated by equating the dry SO2 flux to the Zn corrosion flux. SO2 will deposit onto a dry surface until an amount similar to that of a monolayer has formed. Under wet conditions, the dry deposition flux is controlled by the gas-phase resistance of the atmosphere. Wet deposition of acidic species induces corrosion which depends not only on the pH of the incident rain, but also on the exposure history of the samples.