Cathodic reaction mechanisms in CO2 corrosion of low-Cr steels
The cathodic reaction mechanisms in CO2 corrosion of low-Cr steels were investigated by potentiodynamic polarization and galvanostatic measurements. Distinct but different dominant cathodic reactions were observed at different pH levels. At the higher pH level (pH > ~5), H2CO3 reduction was the dominant cathodic reaction. The reaction was under activation control. At the lower pH level (pH < ~3.5), H+ reduction became the dominant one and the reaction was under diffusion control. In the intermediate area, there was a transition region leading from one cathodic reaction to another. The measured electrochemical impedance spectrum corresponded to the proposed cathodic reaction mechanisms.
Keywordslow alloy steel carbon dioxide corrosion EIS cathodic reaction mechanisms
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This work was financially supported by the National Natural Science Foundation of China (No. 51371034) and Fundamental Research Funds for the Central Universities (No. 06500118).
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