Corrosion potential (Ecorr) for 316L stainless steel coupons was monitored during 9 days in situ exposure to fresh river water. Ecorr increased at 300 mV day−1 reaching potentials of +350 mV (SCE) within 48 hours, then remained fixed at this potential. The coulometric reduction technique was used to determine rate and total abundance of cathodically active manganese biofouling during the exposure. A deposition rate of 0.57 mcoul cm−2 d−1 was measured during the initial 7 days, increasing to 3.1 mcoul cm−2 d−1 between day 7 and 9. Based on a one-electron reduction of MnO2 to MnOOH, 8.8 μg cm−2 electroactive MnO2 was deposited during the 9 day exposure. Comparison with published data for manganese deposition in drinking water distribution systems suggests rapid biological MnO2 deposition consistent with the rapid rate of Ennoblement. Deposition rate is used to estimate the potential impact of manganese biofouling on stainless steel pitting.

Subject
Biofouling, Pits, Water, Corrosion rate, Titration, Manganese, Deposition rate, Ennoblement, Scale formation, Pitting, Deposit corrosion, Stainless steel, Risk reduction
Keywords:
Ecorr, Epit, manganese dioxide, stainless steel, pitting, biofilm, Ennoblement, oxygen, corrosion potential, passive film
© 1996 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).
1996
Association for Materials Protection and Performance (AMPP)
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