Abstract
The effect of carbon dioxide on corrosion rate, polarization curve and hydrogen content has been investigated for carbon steels in acetate solutions and sodium carbonate solution with a pH range of 2 to 9 at 313 K under carbon dioxide and nitrogen atmospheres. In acid solutions less than pH 6 both general corrosion and hydrogen absorption are accelerated by the existence of carbon dioxide, but not clear in the intermeadiate pHs 5 and 6. In the solutions more than pH 6 little corrosion rate is observed regardless of carbon dioxide, whereas hydrogen content is surely detected only at the existence of carbon dioxide. The anodic and cathodic polarization curves show that their reaction overpotentials are affected by carbon dioxide, whose effect changes depending upon pH. The results obtained are qualitatively explained in terms of the formation of iron carbonate and the adsorption of carbonate ions.
