The role of Ca2+ ions on Ca/Fe carbonate products on X65 carbon steel in CO2 corrosion environments at 80 and 150 °C. (1st August 2019)

• Record Type: Journal Article
• Authors: Shamsa, Amir; Barker, Richard; Hua, Yong; Barmatov, Evgeny; Hughes, Trevor L.; Neville, Anne
• Is Part Of: Corrosion science. Volume 156(2019)
• Page Start: 58
• Page End: 70
• Publication Date: 2019-08-01
• Subjects: CO2 corrosion -- High temperature -- Iron carbonate -- Calcium carbonate -- Mixed carbonate; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2019.05.006
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: The addition of 1.83 wt.% Ca 2+ at 80 °C led to the precipitation of thicker and less protective corrosion product layers consisting of Fex Cay CO3 . The addition of Ca 2+ ions at 80 °C accelerated pit growth. Greater uniform corrosion rates were also observed, owing to the establishment of a less protective corrosion product layer. The influence of Ca 2+ ions was less substantial at 150 °C which establishes that mixed carbonates such as Fex Cay CO3 can be as protective as FeCO3 if precipitated under the right conditions. The stoichiometry (x and y) of iron-calcium carbonate (Fex Cay CO3 ) corrosion products can exist with concentration gradients across their depths. Abstract: The role of Ca 2+ ions on the corrosion behaviour of carbon steel in CO2 -corrosion environments was evaluated at 80 °C and 150 °C. In the presence of Ca 2+ ions there was a more significant effect on the general corrosion rate at the lower temperature of 80 °C where the protection afforded by the corrosion product layer was reduced. The extent of localised/pitting corrosion increased through the addition of Ca 2+ ions indicating that Ca 2+ plays a role in promoting localised corrosion. XRD based calculations, along with focused ion beam EDX-line scans confirmed that the mixed Ca/Fe carbonates precipitated with concentration gradients across their thicknesses.