Surface Characterization of Mild Steel During Atmospheric Corrosion After Being Treated by Sodium Dihydrogen Orthophosphate

Resumo

The objective of this study was to characterize the surfaces of the steel products produced locally during their exposure to the industrial and marine atmosphere of the Arabian Gulf region after being treated by sodium dihydrogen orthophosphate. Corrosion rates were determined by weight loss measurements. Sodium dihydrogen orthophosphate performed well throughout the test period. At the end of the exposure duration of 180 days, the corrosion rates of 10 mM sodium dihydrogen orthophosphate treated specimens were 71% of the corrosion rates of the untreated specimens. At certain periods of atmospheric exposure, the (disc shape) specimens were retrieved and studied by SEM and EDS surface analysis techniques. Analysis of the specimens by SEM and EDS at different exposure periods showed that sodium dihydrogen orthophosphate treated surfaces had much lower number of corrosion blisters than those on untreated surfaces at the same period of exposure. They were also smaller in size.