This paper initially reviews the mechanism of MIC with an emphasis on electrochemical aspects. The related charge-transfer (electrochemical) mechanisms of bacterial growth and corrosion are compared on the potential-pH (Pourbaix) diagram. Bacterial consortia isolate micro and macro areas on metal surfaces to create favorable oxidizing/reducing and chemical conditions, maximize biomass growth, and foster localized corrosion. Electrochemical corrosion rate measurements have been conducted over several months on carbon steel exposed to aerobic iron-oxidizing, anaerobic sulfate reducing, and exopolymer producing bacteria, all cultured from the proposed high level nuclear waste storage siteYucca Mountain, Nevada. Taken alone, each of these bacteria increased the electrochemically measured abiotic corrosion rates by a factor of 2 to 3. However, a mixture of all three increased corrosion rates by up to a factor of 5.

Subject
Acids, Electrochemical cells, Bacterial growth, Corrosion rate, Yucca mountain, Pourbaix diagrams, Corrosion reactions, Acidity, Bacteria, Dissolved oxygen, Risk reduction, Microbiologically influenced corrosion, Half cells
Keywords:
Corrosion, MIC, redox potential, microbiology, Pourbaix diagrams, iron-oxidizing bacteria, sulfate-reducing bacteria, exopolymers, polarization resistance
© 1997 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1997
Association for Materials Protection and Performance (AMPP)
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