Electrochemical studies of microbiologically influenced corrosion in natural freshwater system

An electrochemical field study of microbiologically influenced corrosion on carbon steel and stainless steel was conducted in a natural freshwater system. The specimens were exposed in filtered (0.2 μm) and unfiltered lake water respectively. The open-circuit potentials of corrosion specimens and platinum potentials were monitored during the exposures. The electrochemical impedance spectroscopy and polarization data were collected after exposures. The biofouling scraping after exposures was analyzed by microbiological approaches. The results show that the platinum potentials and corrosion potentials in the unfiltered lake water were significantly higher than in the filtered lake water. The ennoblement of the open-circuit potentials was thought to be due to an increase in the exchange current density for the oxygen reaction by the oxygen catalysis mechanism. The catalysis resulted from microbial effects, and was probably associated with the presence of algae.