Biofouling and corrosion of stainless steel of the AISI 430, 304 L and 316 T types and 70/30 copper-nickel alloy were studied after several weeks of exposure to natural seawater. Microfouling taxonomic structure and dominant species were assessed by exposing glass panels in the same sampling areas used for metal samples. The corrosion behavior of the different metals tested was studied in the laboratory by using potentiodynamic polarization methods and open circuit potential vs. time measurements. Microfouling and corrosion attack observation was made by scanning electron microscopy. A different behavior was found for stainless steel and copper-nickel samples in relation to the interaction between biofilms and corrosion. Biofilms affect copper-nickel passivity mainly by reducing the precipitated corrosion layers adhesion, thus facilitating the removal of passive layers leading to a differential aeration effect.

Stainless steel passivity is mainly disturbed through a modification of oxygen concentration gradients at the metal/solution interface. The initiation of pitting and crevice attack is facilitated by the observed ennoblement of the corrosion potential with increasing time of immersion.

Subject
Scanning electron microscopy, Water, Metal surfaces, Seawater, Open circuits, Biofilms, Corrosion products, Metals, Copper nickel alloys, Immersion, Stainless steel, Corrosion potential, Electrode potential
© 1989 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).
1989
Association for Materials Protection and Performance (AMPP)
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