The inhibition effect of 2-mercaptobenzothiazole (MBT) on the corrosion of steel (API 5L X52) in 1 M H2SO4 was investigated by electrochemical and theoretical methods. The results of the investigation show that this compound has excellent inhibiting properties for steel corrosion in sulphuric acid and the inhibition efficiency increases with the increase in inhibitor concentration. The adsorption of the inhibitor on the surface of steel was found to obey a Langmuir adsorption isotherm. The effect of temperature on the corrosion behavior of steel without and with the inhibitors was studied, and the activation and thermodynamic parameters were calculated. Ab initio quantum chemical calculations at the density functional theory (DFT) level were performed to correlate electronic structure parameters of MBT and its different tautomers and conformers with its inhibition performance. The quantitative structure activity relationship (QSAR) approach was also used to correlate the quantum chemical parameters with the experimentally determined inhibition efficiencies.

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Cerium-based conversion coating was deposited on aluminum 6063 and its corrosion behavior was studied. Corrosion resistance was investigated at different pH in 3.5 wt% NaCl solution by means of electrochemical impedance spectroscopy, potentiodynamic polarization, and surface techniques. The coated samples showed a significant decrease in corrosion rate. The coating obtained by 600 s immersion covers uniformly the alloy surface. Electrochemical impedance data shows that with increasing immersion time, the charge transfer resistance of aluminum increased. Surface morphology and its chemical composition were analyzed by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). SEM images in agreement with the electrochemical results indicated that aluminum surface was not completely covered after short immersion time. The EDS analysis confirmed the presence of cerium oxide on the aluminum surface and the cerium content was increased with increasing immersion time.