Abstract
The effects of several commercial corrosion inhibited highway deicers on carbon steel were examined by DC polarization measurements, Energy Dispersive Spectroscopy, and Scanning Electron Microscopy. Polarization measurements indicate that ortho or polyphosphates mixed with magnesium salts and added to deicing salt interfere with the anodic reaction, cause a shift in the corrosion potential toward more passive potentials, and result in corrosion rates that are lower than that observed in pure water with no added salt. A liquid magnesium chloride deicer containing an organic inhibitor exhibits similar characteristics in comparison with salt. Corrosion rate measurements made with the deicer solutions independently by weight loss measurement and by electrochemical Tafel extrapolation were in good agreement. Surface analysis shows that the inhibitors appear to function by becoming incorporated into the surface layer on the steel, transforming the normal porous, unprotective oxide film that forms in the presence of plain deicing salt to a compact, uniform film which can protect the metal from the corrosive environment.
