Preliminary Exposure Study to Determine the Effects of Acid Deposition on Coated Steel Substrates

摘要

The project involves the evaluation of the effects of acidic pollutants on painted metal substrates. The project examined a commercially available alkyd paint/primer system applied to a low carbon steel substrate exposed under a variety of simulated acidic conditions to determine the micro/macro effects of such exposure. The techniques that were identified as those most sensitive and applicable during the study include tensile adhesion testing, electrochemical impedance spectroscopy, and x-ray photoelectron spectroscopy. A novel electrochemical monitor was developed during this program that allowed the continual monitoring of coating degradation during chamber exposure. It was further found that a good correlation existed between tensile adhesion strength measurements and electrochemical impedance parameters. The program determined that the rate of degradation of the alkyd painted steel coupons was accelerated in the presence of SO2. This effect was most pronounced on samples that contained defects (scribes), that were allowed to form condensed (dew) during the exposure period and that had a horizontal orientation during exposure.