Search

Density functional theory was used to investigate the adsorption of imidazole (IMD), benzotriazole (BTAH) and 2-mercaptobenzoxazole (MBO) on the grain boundary (GB) of Cu (100) surface. Results show that molecules prefer to adsorb on the grain boundary with the larger distortion degree and more adsorption sites. The main interaction of molecules and grain boundary is chemisorption through C, N, S Cu bonds in both perpendicular and parallel modes. Hydrogen bonds and the lateral dipole-dipole interactions are also found. Based on the adsorption behaviour, the coverage effect and charge redistribution might be two possible inhibition mechanisms of inhibitor molecules.

Density functional theory calculation was conducted to investigate the adsorption behavior and mechanism of benzotriazole (BTA) on the copper surface with the defects of vacancy, impurity, and grain boundary (GB). On the Cu (111) surface with vacancies, BTA tends to obliquely, rather than vertically, adsorb on the copper surface. The surface doped with Zn and O has stronger adsorption activity for negatively charged particles compared with the surface doped with Ni and S. For impurity and GB surface, the adsorption energy and transferred charge show that the oblique and horizontal adsorption configurations are more stable than the vertical adsorption of BTA. Our findings provide profound explanation for corrosion inhibitor protection of defective metal surface.

Density functional theory was used to investigate the adsorption of three corrosion inhibitors on the Cu(1 1 1) surface in both neutral and dehydrogenated forms, including imidazole, benzimidazole and 2-mercaptobenzimidazole. Results show that three neutral molecules can weakly chemisorb perpendicularly on the surface through N Cu or S Cu bond as well as the X H⋯Metal hydrogen bond (X = C or S). Neutral benzimidazole and 2-mercaptobenzimidazole can physisorb almost parallel to the surface. The dehydrogenated molecules can strongly chemisorb on the surface with both perpendicular and tilt adsorption configurations, and their chemisorption strength order is consistent with the experimental results of inhibiting efficiency.

Exfoliation behavior of extruded 2024-T4 in four coastal environments was investigated by the field testing and laboratory-accelerated test. At the Wanning, Qionghai and Qingdao test sites, exfoliation appeared on 2024-T4 after 6, 10 and 20 years exposure, respectively. At the Guangzhou test site, 2024-T4 did not suffer exfoliation after 20 years exposure. In the laboratory-accelerated test, the effects of relative humidity, temperature and Cl − amount on exfoliation were studied. Exfoliation could not occur on extruded 2024-T4 when RH was below 75%. Above this RH, the higher the temperature or the Cl − amount was, the more serious exfoliation the specimen suffered.

Diffusion of corrosive particles inside inhibitor films consisting of 2-mercaptobenzimidazole (2-SH-BI), 2-aminobenzimidazole (2-NH2-BI), 2-methylbenzimidazole (2-CH3-BI), and benzimidazole (BI) was investigated by molecular dynamics simulation. Diffusion coefficients of various corrosive particles in the films were calculated, following the same order of 2-SH-BI 2-NH2-BI > 2-CH3-BI > BI, which is in good accordance with published experimental results.

Corrosion inhibition performance of four 1-R-2-undecyl-imidazoline compounds (R CH 2 COOH (A), CH 2 CH 2 OH (B), CH 2 CH 2 NH 2 (C) and H (D)) for carbon steel was evaluated by quantum chemistry and molecular mechanics methods. Results indicated that the hydrophilic groups (R) have remarkable influence on molecular reactivity, binding strength between self-assembled monolayer (SAM) and Fe surface, and compactness of the inhibitor SAM. The inhibition efficiency evaluated via theoretical methods was well accorded with reported experimental ones, following the same order as A > B > C > D. This research might provide a theoretical inhibition performance evaluation approach for homologous inhibitors.