Aerobic acetic-acid-producing bacteria can cause the depolarization of an Allegheny-Ludlum 6X stainless steel electrode cathodically polarized to -900 mV vs. SCE in a synthetic seawater solution. Formation of a calcareous film and initial settlement of microorganisms on the electrode surface resulted in decreased current density as a result of impeded oxygen transport and respiration. Subsequent colonization of the electrode resulted in increased current density, i.e., cathodic depolarization. The impact of bulk pH changes on current density during polarization was measured. It appears that colonizing bacteria can accelerate corrosion by producing acetic acid which destabilizes or dissolves the protecting calcareous film that forms during cathodic polarization.

Subject
Scanning electron microscopy, Depolarization, Steel surfaces, Cathodic protection, Acidity, Current densities, Film formation, Bacteria, Acetic acid, Oxygen, Stainless steel, Polarization, Electrodes
© 1987 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).
1987
Association for Materials Protection and Performance (AMPP)
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