Quantitative Analysis Methods of Chloride Deposition on Silver for Atmospheric Corrosion Monitoring in South Korea

The chloride deposition rate is one of critical factors affecting the atmospheric corrosion of metals, which can be monitored by exposing Ag specimens and analyzing their surfaces using various ways. Although a coulometric reduction method can provide an absolute chloride deposition rate, new and alternative methods can be pursued, i.e., methods using typical surface analysis tools (scanning electron microscopy-energy dispersive x-ray spectroscopy [SEM-EDS], x-ray diffraction [XRD], and x-ray photoelectron spectroscopy [XPS]). As the surface analysis tools can only provide relative values, a correlation between the coulometric reduction and surface analyses should be developed. To develop the correlation between them, Ag specimens were prepared by exposing them to the atmosphere at 12 locations in South Korea for one year. Surface analysis of retrieved Ag specimens yielded correlations for the chloride deposition rates between the coulometric reduction method and typical surface analysis tools. Each correlation showed a fairly linear relationship, especially ones obtained from SEM-EDS and XPS. The developed correlations can be used when estimating the chloride deposition rate by using surface analysis tools as an alternative to the coulometric reduction method.