Umwelteinflüsse auf Werkstoffe

Environmental Influences on Material

Abstract

Environmental effects on metallic materials are investigated by the combination of a field exposure programme and laboratory exposures. The exposure sites were chosen at locations of the Swiss National Air Pollution Monitoring Network (NABEL) in different regions of Switzerland. Using material loss and the type of corrosion products formed after four years in conjunction with the local climate data, the relevant parameters for the corrosion of the materials investigated can be deduced. Further insights into the mechanism are gained by laboratory exposures carried out in humid air containing single air pollutants (SO₂, NO, NO₂, O₃, laboratory air). Sulfur dioxide and the time of wetness are playing the most important factors for the corrosion of unalloyed carbon steel, zinc, and hot-dip galvanized steel. In the case of copper, ozone has to be considered in addition. The analysis of the mass of corrosion products retained on the surface of zinc samples showed that in the case of unsheltered specimens ca. 60% of the corroded zinc was lost while for the sheltered samples 90% of the corroded zinc remained on the surface of the specimen. The results of the study can be used for the evalutation of the air protection measures.