Thermal sprayed coatings are used for corrosion protection of structures in marine atmosphere. After a considerable operating time, a part of the sprayed coating will be degradated and/or exfoliated. Practically, the protectiveness of exfoliated coating is an issue of great interest in that, by knowing this, one can determine the repair timing and predict the remaining service life of impaired coating. Electrochemical properties of metal (Al-2%Zn) coating, flame sprayed on aluminum substrate (AA 5083) followed by epoxy sealing, were investigated by various laboratory tests such as corrosion potential trends and polarization behavior. From the difference of the corrosion potential between the substrate and the coating layer, it is considered that the coating can sufficiently cathodically protect the substrate. To assess the protective performance of the coating system, visual inspection on the surface was made and the residual coating thickness and the potential of the coating were simultaneously measured. One can find the relationship between the thickness and the potential and determine the protection potential criterion for substrate.

Subject
Coatings, Substrates, Aluminum, Spray coating, Exfoliation, Potential measurements, Coating degradation, Epoxy coatings, Corrosion protection, Protection potential, Corrosion potential, Coating systems, Thermal spray coatings
Keywords:
thermal sprayed coating, coating exfoliation, protective performance, protection potential criterion, service life assessment
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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