INTERFACIAL PHENOMENA IN BIOCORROSION

In natural environments, microbes attach to engineering materials and colonize the surfaces to produce biofilms. Biofilms mediate the intera ctions between surfaces and environment resulting in serious energy lo sses, reduced equipment performance and corrosion failures in several defence and industrial systems. The chemical processing industry, oil and gas industry, power generation industry and the defence services h ave acknowledged the prevalence of biocorrosion in their operating sys tems. Microbial activity seemed to be involved in most of the cases of failure of the systems where mild steel, iron and copper alloys were used. The present paper incorporates the data obtained in respect of t hree different corrosion behaviours of structural materials viz., an e asily corrodable surface (mild steel), a corrosion resistant surface ( 304 stainless steel) and a complex corrosion behaviour (copper)..Micro biological and electrochemical methods have been used to study the int erfacial properties of metallic surfaces covered with biofilms. The bi ologically conditioned interfaces have been characterised by selecting suitable parameters in metal biofilm systems. The biofilm/passive lay er interactions have been interpreted on the basis of charge transfer and diffusion controlled reactions taking into account adsorbed reacti on intermediates or products.