Corrosion inhibition and surface analysis of amines on mild steel in chloride medium

Abstract

In this study, the corrosion inhibition effectiveness of eight amines, i.e. 2-ethylhexyl amine, aniline, benzylamine, butylamine, ethylamine, isopropylamine, octylamine, and triethanolamine, on C15 grade mild steel in 3 wt% NaCl solution is reported. The corrosion inhibition performance of the amines was studied using immersion tests at 25 and 70 °C, with and without the addition of KI as a possible intensifier. Among the inhibitors tested at 0.1 wt% concentration, the lowest corrosion rates were obtained for specimens immersed in solutions containing 2-ethylhexyl amine at 25 °C and triethanolamine at 70 °C. The highest inhibition effectiveness at 25 °C among all amines tested was obtained for 1.0 wt% butylamine with the addition of 0.5 wt% KI, while at 70 °C the lowest corrosion rate was obtained for specimens inhibited with 1.0 wt% isopropylamine. Surface analysis was subsequently performed on specimens inhibited by the most effective inhibitors. Adsorption of the selected amines on the C15 grade mild steel surface was confirmed by ATR-FTIR. 3D-profilometry showed a reduction in the surface roughness (less corroded) for the specimens inhibited with these inhibitors compared to the non-inhibited specimens. Contact angle measurements showed that all of the tested specimens were hydrophilic.