This study is a continuation of the investigation initiated in the lab a couple of years ago to understand the value of using electrochemical techniques such as cyclic polarization (CP) and electrochemical impedance spectroscopy (EIS) to assess, rank, and predict the tendency of corrosion inhibitors (batch and continuous) to protect carbon steel surfaces from localized corrosion (pitting). The first part of this study proved out the good correlation between the results obtained with electrochemistry methods and the long-term immersion/autoclave testing. General corrosion rates from weight loss using rotating cage autoclave (RCA) tests and CP/EIS scans using rotating cylinder electrode (RCE) tests showed similar tendencies in most of the products tested (87% correlation was achieved). Based on the promising results obtained in Phase I of this investigation, Phase II focused on the 13% of the cases where there was no correlation and the changes needed to be made from the experimental standpoint to improve the correlation rate to 100%. For that purpose, in this study, one corrosion inhibitor formulation was tested at three different dose rates and the electrochemical methods were successfully used to identify at which dose rate no pitting was observed.

Subject
Electrochemical impedance spectroscopy, Steel surfaces, Inhibitor performance, Cyclic polarization, Corrosion rate, Autoclaves, Steel coupons, Dosages, General corrosion rate, Corrosion inhibitors, Pitting, Corrosion coupons, Anodic inhibitors
Keywords:
Electrochemical Impedance Spectroscopy (EIS), Cyclic Polarization (CP), Corrosion Inhibitor, Pitting, Corrosion rate
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2023
Association for Materials Protection and Performance (AMPP)
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