The mechanism of the cathodic reaction in acetic acid corrosion of iron and API X65 mild steel was investigated in mildly acidic sodium chloride electrolytes. The behavior of the charge transfer controlled currents in the steady state voltammograms showed that undissociated acetic acid is not significantly electroactive. This behavior was found to be in accordance with the so-called “buffering effect” mechanism, where acetic acid acts solely as an additional source of hydrogen ions. The increased limiting currents in the presence of acetic acid showed a linear correlation with undissociated acetic acid concentration in agreement with the Levich equation, suggesting that the limiting currents are under mass transfer control. Both pure iron and X65 steel exhibited a similar behavior regarding the cathodic currents, indicating that the mechanism of hydrogen ion reduction is not influenced by minor impurities present in the X65 steel.

Subject
Acid concentration, Weak acids, Cathodic current, Sodium chloride, Iron, Corrosion reactions, Acidity, Ion concentrations, Steel, Acetic acid, Risk reduction, Electrodes, Hydrogen
Keywords:
acetic acid, acidic corrosion, aqueous environments, cathodic polarization, mechanism, mild steel, uniform corrosion
© 2016, NACE International
2016
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