Corrosion Behaviors of Carbon Steel and Stainless Steel in the Presence of Iron Oxidizing Bacteria Acidithiobacillus ferrooxidans

摘要

In this study, corrosion behaviors of carbon steel UNS G10100 and stainless steel UNS S30400 in the presence of an iron-oxidizing bacterial species: Acidithiobacillus ferrooxidans, were examined. Results showed that A. ferrooxidans cells, with or without attaching to coupons, could accelerate UNS G10100 corrosion at a rate of 3 - 6× that of controls without A. ferrooxidans, but showed no effect on UNS S30400 corrosion. The accelerated corrosion of UNS G10100 by A. ferrooxidans cells was due to the presence of Fe~(3+), produced by the metabolism of A. ferrooxidans cells when utilizing Fe~(2+) as the energy source to fix CO_2 into glucose. The fast reaction of Fe~(3+) with Fe~0 to form Fe~(2+) was prevented in the systems containing UNS S30400, probably by the chromium rich passivating layer formed on UNS S30400 surface to block the accessibility to Fe~0. Without Fe~(2+), A. ferrooxidans cells died off, eliminating their contribution in UNS S30400 corrosion.