TECHNIQUES FOR STUDYING INITIAL BACTERIAL ATTACHMENT AND SUBSEQUENT CORROSION OF METALS

摘要

Microbiologically influenced corrosion (MIC) is a widespread problem in a range of industries such as maritime, oil and gas, nuclear and power generation. The first step in the interaction between microorganisms and the metal surface is the attachment of microorganisms, which is considered to be responsible for MIC. In the present study, methods for investigating the initial attachment of bacteria to a metal substrate are compared. As a model system, finely polished 1010 carbon steel coupons were exposed to E. coli bacteria in a minimal medium. The coupons were exposed for different time intervals, up to a period of 4 hours, to investigate the initial bacterial attachment and the subsequent corrosion. A range of techniques including 3D optical profilometry, light microscopy and scanning electron microscopy (SEM) were used to study the bacterial attachment and its effect on the corrosion of the steel coupons. Additional analysis techniques are described for quantitatively correlating bacterial attachment patterns with the steel microstructure. The results indicate that the initial bacterial attachment (i.e. < 60 min) preferentially occurred at or near the grain boundaries of the steel coupons. The longer term (4 hour) immersion tests resulted in the formation of biofilm and corrosion at the grain boundaries of the steel coupons, whereas no corrosion was observed in the absence of bacteria. It was found that the 3D optical profilometer provides a rapid, non-destructive and direct measurement of bacterial/substrate interaction compared to other conventional microscopic techniques.