Effect of Fe ion concentration on corrosion of carbon steel in CO₂ environment

Abstract

In this work, the corrosion behaviour of steel wires in solutions containing different concentrations of Fe²⁺ was investigated by the linear polarisation resistance method, while the evolution of pH was monitored in situ and changes of the Fe²⁺ concentration were monitored ex situ. Characterisation of the corrosion scales was performed using microscopic and diffraction techniques. Scale analysis revealed that the passivation of samples, exposed to initially highly Fe²⁺ supersaturated solution, occurred when a formation of a double layer took place, resulting in 30 times lower corrosion rate compared to samples tested in solutions without initial Fe²⁺.

Keywords:

• Carbon steel
• Carbon dioxide
• Supersaturation
• Linear polarisation resistance
• Scanning electron microscopy
• X-ray diffraction
• Passivation

Acknowledgement

The authors would like to acknowledge InnovationsFonden in Denmark for providing financial support in the project.