Synchrotron far-infrared spectroscopy of corroded steel surfaces using a variable angle of incidence

Abstract

Far-infrared spectroscopy, using a synchrotron source, has been used to study carbon steel corroded in CO2-saturated brine in the presence and absence of the corrosion inhibitor 2-mercaptopyrimidine (MPY), which allowed the steel surface roughness to be modified. The effect of the angle of incidence (θi, 30-80°) on the band intensity and observed bands of the spectra from these surfaces has been determined. For the MPY-treated steel (low surface roughness) the highest band intensity is observed at high θi (80°) and different bands were observed at different θi. In contrast, for the MPY-free steel (high surface roughness) the highest band intensity is observed at low θi (30°) and spectral content changes were not observed. The results are explained in terms of the roughness of the MPY-treated and MPY-free steels, and their effect on the level of diffusely reflected light of the incident infrared beam.

Carbon steel corrosion: a review of key surface properties and characterization methods

“…FTIR studies in the far-infrared region have not been widely applied in corrosion science despite the theoretical possibility of identication of the absorption bands characteristic for corrosion products or corrosion inhibitors. Lepkova et al 147 utilized synchrotron-sourced far-infrared spectroscopy to study carbon steel exposed to CO 2 -saturated brine in the presence and absence of a corrosion inhibitor, 2-mercaptopyrimidine (MPY). The study used variable grazing angle of incidence to optimize the experimental settings suitable for analysis of thin lms on corrosion-roughened carbon steels.…”