||Theoretical Damage Function for the Effects of Acid Deposition on Galvanized Steel Structures.
Spence, J. W. ;
Haynie, F. H. ;
||Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Sciences Research Lab.
Atmospheric corrosion ;
Galvanized materials ;
Mathematical models ;
Research projects ;
Zinc coatings ;
Acid resistance tests ;
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A theoretical damage function for predicting the corrosion of galvanized steel structures by wet and dry deposition has been developed from thermodynamics and kinetics of atmospheric corrosion chemistry. The function mathematically expresses the competing reactions for the build up and dissolution of the basic zinc carbonate corrosion film with exposure time. Major scientific findings are as follows: During periods of surface wetness SO2 reaching the surface reacts stoichiometrically with the zinc. Rain acidity reacts stoichiometrically with the zinc. The corrosion film of basic zinc carbonate is soluble in clean rain. The dissolution depends on the residence time of rain on the galvanized steel surface. Deposition velocity controls the rate of corrosion of galvanized steel structures by gaseous SO2 during periods of wetness.