The Influence On Corrosion Behavior Of Carbon Steel By Bacteria Isolated From Inner Rust Layer

As the economy and society developes, the shortage of energy sources becomes even severer, meanwhile the environment becomes more deteriorative. Being a promising place for human, the ocean is catching unprecedented attention of researchers. The property of seawater is special because of containing high salt, and in this case the material in it can be corroded easily. It cannot be neglected for not only serious waste but also unnecessary disasters occur easily in this environment. Microbes distribute widely in marine environment, and Microbiologically influenced corrosion(MIC) has been an significant part of corrosion that cannot be neglected.Sulfate-reducing bacteria(SRB), iron bacteria and manganese oxidation bacteria etc. are important species which influence corrosion process of materials. New pattern of the mechanism of MIC can offer necessary theoretical basis for MIC control.In this study, we try to isolate bacteria from rust layer of steel in natural marine environment, and analyze the diversity of microbes that can be cultivated in it. In addition, study the influence on the corrosion behavior of carbon steel of these isolated species(including aerobic bacteria, iron bacteria and sulfate-reducing bacteria). Conclusions are as follows:21 bacteria and 13 bacteria were isolated from inner rust layer of carbon steel by 2216 E culture medium and PGC medium separately. Phylogenetic analysis of 16 S r DNA were conducted and the results indicated that there was high diversity of bacteria in carbon rust layer, and Bacterium accounts the most part.Weight loss and electrochemical measurements and surfaces analysis were conducted to investigate the influence on the corrosion behavior of carbon steel by these bacterias. The influence on the corrosion behavior of carbon steel by aerobic bacteria is slightly. In a word, they can inhibit corrosion to some extent because of the depletion oxygen on the surface of material and reduce the cathodic depolarization process. Pure sulfate-reducing bacteria accelerate the corrosion rate of carbon steel and pit corrosion occur under biofilms. However, the mixture can inhibit corrosion of carbon steel slightly. Iron bacteria can accelerate the corrosion rate in initial stage of immersion and inhibit corrosion in late stage of immersion.