Traditional corrosion-measuring techniques applied to the study of microbially induced corrosion cannot distinguish between biotic and abiotic contributions. This paper describes a technique that permits this distinction. A cell composed of two galvanically coupled compartments, electrolytically connected but biologically separated, has been used to evaluate the electrochemical impact of naturally occurring estuarine microorganisms on four metal substrata. The colonizing species and the electrochemical impact of colonization varied among the metals evaluated. Preferential selection of substratum by different microbes was documented by microscopic examination of metals similarly exposed to a mixed culture. Anodic currents were measured on titanium and nickel surfaces. Erratic anodic/cathodic fluctuating currents were observed with copper-nickel and carbon steel, which may be the result of symbiotic oxidations and reductions that characterize mixed cultures. It was further demonstrated that in the presence of differential aeration cells, such as those created by respiring microcolonies, an anode occurs at the lower oxygen site and a cathode results at the site of higher oxygen. Acidic microbial metabolites were also shown to enhance corrosion.

Subject
Acids, Water, Corrosion currents, Current measurements, Platinum, Metals, Anodic current, Oxygen, Titanium, Carbon steel, Nickel, Electrodes, Microorganisms
© 1986 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).
1986
Association for Materials Protection and Performance (AMPP)
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