Inhibition effect of azole derivate on corrosion activity of copper in rolling oil

Corrosion rates are influenced by the formation of inhibitor aggregates on the copper surface. Laser scanning confocal microscope was used to investigate the adsorbed structures of benzotriazole, N‐((6‐methyl‐1H‐benzo[d][1,2,3]triazol‐1‐yl)methyl)‐N‐octyloctan‐1‐amine (MBA) and 2,5‐bis (ethyldisulfanyl)‐1,3,4‐thiadiazole at copper surface in relation to their performance as a corrosion inhibitor. The increase of water contact angle in the presence of inhibitor indicates its strong adsorption to the copper, and laser scanning confocal microscope visualization confirms the formation of MBA aggregates. The aggregates change from hemispherical to cylindrical shape with MBA concentration increasing in rolling oil, resulting in a decrease in corrosion rates as determined by mass loss measurements. Compared with 2,5‐bis (ethyldisulfanyl)‐1,3,4‐thiadiazole, oil‐added MBA has a quicker adsorption and formation speed of cylindrical aggregates and a lower corrosion rate. The adsorption of inhibitors on copper surface obeys Langmuir isotherm and physisorption and chemisorption mechanism. Copyright © 2015 John Wiley & Sons, Ltd.