부산대학교 도서관

The effect of HCO3(superscript -) concentration on CO2 corrosion were investigated by polarization measurement of potentiodynamic scans and weight loss method in this paper. Under high pressure and high temperature, the corrosion rate of steel X65 decreased with the increase of HCO3(superscript -) concentration while pH increased. SEM, EDS, XRD results of the corrosion scales indicated that a typical FeCO3 crystallite was found at low HCO3(superscript -) concentration but Ca(Fe,Mg)(CO3)2 at high HCO3(superscript -) concentration. Ca(superscript 2+), Mg(superscript 2+) precipitated prior to Fe(superscript 2+) at high pH value. Potentiodynamic polarization curves showed that the cathodic current density decreased with increase of HCO3(superscript -) concentration at low HCO3(superscript -) concentration. When HCO3(superscript -) concentration reached 0.126 M, increasing HCO3(superscript -) concentration promoted cathodic reactions. Anodic behavior was an active process at low HCO3(superscript -) concentration and the anodic current density decreased with the increase of HCO3(superscript -) concentration. An evident active-passive behavior exhibited in anodic process at 0.126 M HCO3(superscript -).