Effect of acetic acid on CO2 corrosion of carbon steel in NaCl solution

Abstract

AbstractPotentiodynamic sweep and electrochemical impedance spectroscopy measurements were applied to investigate the effects of both temperature and acetic acid (HAc) on the anodic and cathodic reactions in CO2 corrosion of P110 steel in 3.5% NaCl solution. The temperatures were controlled at 30 and 60 °C. The concentrations of HAc were controlled at 0, 1000, 3000 and 5000 ppm. In this work, the corrosion parameters of polarization curves, such as corrosion potential (Ecorr), corrosion current density (icorr), and anodic and cathodic branch slopes (ba and bc), are presented and discussed in detail. In addition, the equivalent circuit models and ZsimpWin software were utilized to discuss the Nyquist plots. The plots showed that the Ecorr values shifted in the positive direction as the HAc concentration increased. The icorr values increased with the increase in HAc concentration, indicating that HAc could accelerate the corrosion. The impedance spectra measured at 30 and 60 °C have different time constants and characterization. The coverage fraction θ and the thickness L of corrosion film are two most important controlled variables that influence and control the CO2 corrosion mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.