Evaluation of Corrosion Inhibition of Mild Steel in 3.5 wt% NaCl Solution by Cerium Nitrate

The effect of cerium nitrate on the corrosion properties of mild steel in 3.5 wt% NaCl solution was investigated via weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization methods. Attenuated total reflectance Fourier-transform infrared spectroscopy and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy were used to study the corroded surfaces of the specimens at the presence of different concentrations of cerium nitrate. Results demonstrated that the maximum inhibition efficiency of cerium nitrate reached 98.9% in the presence of 750 ppm. The potentiodynamic polarization tests indicated that cerium nitrate acted as a cathodic inhibitor. The results revealed a high corrosion inhibition performance of cerium nitrate which is attributed to the formation of a thick film composed of a porous outer layer and a more compact inner layer with a high level of corrosion resistance particularly after 24 h. Surface film analysis confirmed the presence of Ce3+ ions incorporated into the protective film. Graphic The inhibition action of cerium nitrate for mild steel happens by affecting the cathodic reactions. Cathodic reaction generates an alkaline environment that leads to localized precipitation of hydrated rare-earth oxide acting as a protective film. Protective thick layer is composed of a porous outer layer and a more compact inner layer.