Corrosion behaviour of steel in the presence of rare earth salts: synergistic effect

Abstract

In this work, the inhibition behaviour of rare earth (RE) salts (Y(NO₃)₃.6H₂O, CeCl₃.7H₂O) in conjunction with metasilicates (Na₂SiO₃.5H₂O) for carbon steel A37 and in aerated 3%NaCl solutions has been investigated. Corrosion inhibition power evaluation and surface layer characterisation have been carried out by electrochemical measurements (potentiodynamic polarisation and impedance) followed by X-ray photoelectron spectroscopy. It was demonstrated that the binary RE/ improved the protective role of oxide/hydroxide films formed on the steel. Electrochemical tests showed that the cathodic and anodic reactions were both inhibited to some extent, leading to a decreased rate of the global corrosion process. The maximum protective inhibition against corrosion attack was evident when an RE/ ion mixture was added. Surface analysis revealed the diverse nature of inhibitor coverage on the steel.

Keywords:

• Rare earth salts
• Inhibitors
• Corrosion
• Carbon steel
• Impedance