Effect of the pH of the electrolyte on the formation and on the corrosion properties of ceria based coating on carbon steel

International audienceThe effects of the modification of the pH in 0.1M cerium nitrate solutions in the elaboration and corrosion resistance of ceria based coatings on carbon steel are investigated. Increasing the concentration of acetic acid impedes an efficient electrodeposition. At low concentrations, acetic acid seems to prevent the precipitation of Ce(OH)3 and the formation of even films of cerium oxides is favoured. The increase of pH through the addition of NaOH to the cerium nitrate solutions with 0.008M of acetic acid is shown to provide superior corrosion resistance for exposures in air and immersed in 0.5M NaCl for 30 days

Effect of the temperature of cerium nitrate–NaCl solution on corrosion inhibition of mild steel

International audienceIn this work, the effect of temperature on corrosion inhibition was studied in the absence and presence an optimal concentration of cerium nitrate (600 mg.L-1) as an inhibitor of mild steel in sodium chloride. Corrosion tests were carried out through electrochemical techniques such as impedance spectroscopy and d.c polarization measurements. The surface morphology of the films was investigated by optical microscopy (MO), white light interferometry (WLI) and a scanning electronic microscopy (SEM) coupled to EDS analysis for chemical composition. The results obtained show that the activation energy for the corrosion inhibition process to occur increased in the presence of cerium nitrate inhibitor. However, the corrosion resistance of mild steel was somewhat lost with increasing the solution temperature up to 55 °C, which lead to more cracked films. The enthalpy and entropy values suggested a mixed mechanism of chemisorption and physisorption inihibition, with a major dominant of physisorption control