Different effects of three soil microfloras on the corrosion of copper

Many studies have indicated that microorganisms provide less protection or even detrimental effects to metals and alloys. In this study, surface analytical (SEM and EDS) and electrochemical techniques (polarization curves and EIS) were used to analyze the behaviour of copper corrosion by actinomyces, fungi and bacteria, which were isolated from the soil. Many pits and craters were presented on the copper surfaces after incubation with these three microfloras, and clear differences in the corrosion products and morphologies of the copper samples were observed in the fungi and bacteria groups compared with the control. The biofilm layer and the cumulated corrosion products are associated with an oxygen concentration cell, which may influence the corrosion susceptibility of copper. Our results suggest that the corrosion rate of copper samples increases more rapidly in the bacteria groups than in the actinomyces, while in the fungi groups it displays a volatile change with a large amplitude.