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The use of cerium oxide nanoparticles as a corrosion inhibitor for the CO2 corrosion of LDX 2101 duplex stainless steel has been evaluated using potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy tests. Polarization curves have shown that CeO2 nanoparticles behaved as an efficient mixed type of inhibitor, with an efficiency that increases with its concentration reaching a maximum value when 600 ppm of nanoparticles were added. CeO2 nanoparticles were chemically adsorbed onto the steel surface according to a Langmuir type of adsorption isotherm. A passive layer was formed by the addition of CeO2 nanoparticles with lower passive current density and higher pitting potential values than those obtained without these nanoparticles. Corrosion current density decreased whereas the polarization resistance increased by two orders of magnitude in both cases with the addition of the nanoparticles. Similarly, the double layer capacitance was decreased due to the adsorption of the nanoparticles. Steel was susceptible to pitting type of corrosion, but its number and diameter decreased with the nanoparticles.

The corrosion behavior of 1018 carbon steel in LiCl/H2O mixtures has been evaluated by using potentiodynamic polarization curves, electrochemical noise and electrochemical impedance spectroscopy techniques. Two different concentrations of LiCl were employed, namely 35 and 40 wt. %, and the testing temperatures included 25, 35 and 70 °C. It was found that the steel showed a passive zone; the corrosion current density value increased with an increase in the solution temperature and concentration. The pitting potential value decreased with an increase in the testing temperature and the solution concentration. The corrosion process was under charge transfer control. This mechanism was unaltered either by the solution temperature or concentration. The charge transfer resistance value decreased with an increase in both the solution temperature and concentration. A localized, pitting type of corrosion dominated the corrosion morphology at 25 and 35 °C, whereas at 70 °C, the main type of attack was a mixed type of corrosion.

The corrosion behavior of pure aluminum (Al) in 20 v/v% ethanol–gasoline blends has been studied using electrochemical techniques. Ethanol was obtained from different fruits including sugar cane, oranges, apples, or mangos, whereas other techniques included lineal polarization resistance, electrochemical noise, and electrochemical impedance spectroscopy for 90 days. Results have shown that corrosion rates for Al in all the blends were higher than that obtained in gasoline. In addition, the highest corrosion rate was obtained in the blend containing ethanol obtained from sugar cane. The corrosion process was under charge transfer control in all blends; however, for some exposure times, it was under the adsorption/desorption control of an intermediate compound. Al was susceptible to a localized, plotting type of corrosion in all blends, but they were bigger in size and in number in the blend containing ethanol obtained from sugar cane.