The effect of acetic acid and acetate on corrosion behavior of carbon steel (N80) in CO2 saturated 1%NaCl at different temperature and pressure was investigated by using weight-loss, electrochemical methods (polarization curve, impedance) and surface analysis techniques (SEM, XRD). The attention was focused on the effect of acetic acid and acetate on the anodic and cathodic reactions respectively. The results indicate that ①the determining step of cathodic reaction of CO2 corrosion is a inhomogeneous chemical reaction (CO2 hydrated reaction) at the electrode surface. Because acetic acid adsorbed on electrode surface can be reduced directly by electrochemical reaction, acetic acid and acetate promote the cathodic reduction reaction, and as a result, the corrosion rate was accelerated and independent of pH value of solutions. ②The intermediates produced in the anodic processes play an important role in the anodic dissolution. Acetic acid and acetate affect evidently on the formation and adsorption of the intermediates, and run to form more soluble corrosion products. ③The effect of acetic acid and acetate on CO2 corrosion depends on the CO2 fractional pressure, temperature and corroded surface state etc.

Subject
Steel surfaces, Corrosion rate, Cathodic potential, Anode surfaces, Acetates, Polarization curves, Corrosion products, Anodic reactions, Steel, Acetic acid, Carbon steel, Electrodes, Corrosion potential
Keywords:
acetic acid, acetate, effect, CO2 corrosion, carbon steel
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2005
Association for Materials Protection and Performance (AMPP)
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