Abstract The inhibitory effect of Oxethazaine drug, 2,2'-(2-Hydroxyethylimino)bis[N-(alphaalpha-dimethylphenethyl)-N-methylacetamide] on corrosion of mild steel in 1M HCl solution was studied by weight loss measurements, electrochemical impedance spectroscopy and potentiodynamic polarization methods. The results of gravimetric and electrochemical methods demonstrated that the inhibition efficiency increased with an increase in inhibitor concentration in 1M HCl solution. The results from electrochemical impedance spectroscopy proved that the inhibition action of this drug was due to adsorption on the metal surface. Potentiodynamic polarization studies revealed that the molecule was a mixed type inhibitor. The adsorption of the molecule on the metal surface was found to obey Langmuir Adsorption isotherm. Potential of zero charge at the metal-solution interface was measured to provide the inhibition mechanism. The temperature dependence of the corrosion rate was also studied in the temperature range from 30 to 50 °C. Quantum chemical calculations were applied to correlate electronic structure parameters of the drug with its inhibition performance. The obtained theoretical results have been adapted with the experimental data.

In this study, cerium-based conversion coating was deposited on steel X52 by dip immersion method. Cerium oxide/hydroxide is an environmentally friendly conversion coating. The effects of immersion times and immersion temperatures on corrosion properties of cerium conversion coating on steel X52 were studied. Its corrosion resistance in 3.5 wt.% NaCl solution was investigated by means of electrochemical impedance spectroscopy, potentiodynamic polarization, and surface techniques. The coated samples showed a significant decrease in corrosion rate and corrosion current decreased with increasing immersion time up to 60 s. In addition, electrochemical impedance data showed that in the presence of cerium oxide conversion coatings, the charge transfer resistance of aluminum increased. The experimental results indicated that the corrosion resistance decreased with increasing the operating temperature. Surface morphology and its chemical composition were analyzed by means of scanning electron microscopy and energy dispersive spectroscopy.

The formation and corrosion performance of zinc phosphate coating on carbon steel at different temperatures and immersion times was studied. The corrosion performance of coatings was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. The characterization and composition of coatings were studied by SEM and EDS analysis. The corrosion resistance in 3.5%wt. NaCl solution was increased in the presence of zinc phospoate conversion coatings. The effect of immersion time and coating temperature were studied on anti-corrosion behavior of coatings. Coating temperature showed a significant effect in phosphate conversion coating and higher corrosion resistance was obtained with 45 ºC operating temperature. Also the experimental results indicated that the corrosion resistance increased with increasing the immersion time. This behavior can be related to the increase of the phosphate coating continuity which formed on the surface. Surface analysis results indicated that the coating obtained from 20 min immersion time was more uniform and continuous.