Stainless Steel Electrochemical Corrosion Behaviors Induced by Sulphate Reducing Bacteria in Different Aerated Conditions
The emphasis of this study lies in the differences of 304 stainless steel electrochemical corrosion behavior induced by the metabolic activity of Sulphate reducing bacteria (SRB) in a growth cycle under aerobic (oxygen saturated and air saturated culture solutions) and anaerobic (nitrogen saturated culture solutions) conditions. The corrosion process, bio film formation and the composition of the passive film in different conditions are investigated with electrochemical measurements, scanning electron microscopy and X ray photoelectron spectroscopy. Both open circuit potential and electrochemical impedance spectra results indicate that the metabolic activity of SRB can accelerate the electrochemical corrosion process of stainless steel in both aerobic and anaerobic conditions, although the bio film formed can inhibit the erosion of corrosive medium to some extent. The oxygen saturated environment can reduce the corrosion process by inhibiting the metabolic activity of SRB and promoting the passivation of stainless steel, but the air saturated environment presents little effect to the electrochemical property for the low concentration of oxygen. Furthermore, glomerate phenomenon can be observed from the biofilm formed in oxygen saturated culture solutions, indicating that SRB are prone to build localized anaerobic environment for its survival.