Attachment efficiencies of salt aerosols onto infrastructure and implications for atmospheric corrosion

To support a holistic approach to the modeling of atmospheric corrosion, an experimental program was undertaken to delineate the effects of relative humidity, wind speed, and infrastructure surface chemistry on the efficiency of salt aerosol retention. The fundamental adhesion between a salt crystal and a metal oxide surface was studied using colloid probe atomic force microscopy. The magnitude of adhesion was dependant upon the probe dimensions, surface chemistry, and relative humidity. Parallel experiments investigated the removal of salt particles/aerosols from both clean hydrophilic and hydrophobized glass slide surfaces in a wind tunnel. The efficiency of the removal of particulates from glass surfaces was found to be a function of relative humidity, and the influence of humidity and wind velocity appeared to be magnified by increasing the glass hydrophobicity. Furthermore, alterations in the glass surface chemistry led to notable differences in the size and, distribution of adsorbed salts. The experimentally determined salt retention efficiencies enable current holistic lifetime prediction models to be updated and expanded, and provides insight into the ability of surface chemistry to control aerosol retention processes and thus atmospheric corrosion. (c) 2005 The Electrochemical Society. All rights reserved.