The Influence of Microorganisms on the Corrosion and Protection of Metals: An Overview

MICROORGANISMS INFLUENCE ON PROTECTION AND PASSIVITY OF METALS. A CRITICAL OVERVIEW.

 

Hector A.Videla – National Technological University (UTN), 1900 La Plata. ARGENTINA.

 

Liz Karen Herrera – Institute for Materials Science- (ICMSE-CSIC), 41092  Seville, SPAIN.

 

Microorganisms are able to induce drastic changes at the metal/solution interface by forming biofilms including bacteria consortia and expolymeric substances as main components.

Biofilm presence generally facilitates the initiation of localized corrosion but this effect can be reversed to corrosion inhibition.

These opposite effects are rarely linked to a single mechanism or to a single species of microorganism. In the last years microbial inhibition of corrosion and protection of metals have been attributed to the blocking effects of biofilms and EPS. However, this simplistic approach must be discussed from an electrochemical point of view to understand the complex metal microbe interactions at the metal surface. With this aim several practical cases involving sulfate-reducing bacteria, some of them, previously described in the literature are critically discussed. General mechanisms for interpreting microorganisms influence on protection and passivity of metals are presented.

Key words : MIC, biocorrosion, biofilms, corrosion inhibition, passivity, metal protection.