Effect of a High Concentration of Chloride Ions on the Corrosion Behaviour of X80 Pipeline Steel in 0.5 mol L-1 NaHCO3 Solutions

Abstract

A dynamic potential polarization technique and electrochemical impedance spectroscopy (EIS) measurements were used to explore the effects of a high concentration of chloride ions on the electrochemical corrosion properties of X80 pipeline steel in 0.5 mol L -1 NaHCO 3 solutions. The surface corrosion morphology of X80 steel after polarization measurements was observed by scanning electron microscopy (SEM). The electrochemical results showed that the corrosion-product resistance and charge-transfer resistance decrease gradually with the increase of chloride ions, which resulted in the corrosion current density increasing monotonically. The surface corrosion morphology showed no pit formation in 0.5 mol L -1 NaHCO 3 solutions without chloride ions. However, the addition of chloride ions decreases the stability of the passive film, and the density, size and depth of the corrosion pits increased with the increasing concentrations of chloride ions. Therefore, high concentrations of chloride ions greatly affected the electrochemical characteristics and caused further development of pitting in 0.5 mol L -1 NaHCO 3 solutions.

Fabrication of Functionalized Graphene Coated OTFT Humidity and Chloride Ion Sensors for Detecting Corrosion Precursors in Metallic Structures

“…Studies have suggested that the presence of chloride ions and high levels of humidity offer the right conditions for corrosion onset, which have a significant impact on the integrity and durability of metallic structures. Chloride ion thresholds for corrosion initiantion has been identified to be within the range of 100 ppm and 3500 ppm depending on the type of metal alloy, temperature and pH [30,31].…”