Existing coupled multielectrode array sensors are promising devices for application as an online tool for corrosion monitoring. However, most of these devices have an upper operating temperature limit of approximately 70 °C. At temperatures above 70 °C, crevice formation between the electrode and the mounting material (epoxy) may result in erroneous corrosion rate measurements. In this paper, a new electrochemical corrosion monitoring system that has high temperature (>100 °C) capability is presented. A diamond-like carbon thin film was deposited on the sensing electrodes. The coated surfaces exhibited high electrical impedance after testing in caustic (pH = 10) solution at 250 °C. The effectiveness of the diamond-like carbon film in protecting the electrodes was demonstrated in a corrosive solution containing NaCl-NaNO3-KNO3 salt mixture at 150 °C. The new corrosion monitoring system has potential application for monitoring corrosion rate for container materials in potential nuclear waste repositories and in the high temperature systems of nuclear power plants.

Subject
Sensors, Materials, Salts, Corrosion rate, Impedance, Wiring, Mixtures, Solutions, Corrosion probes, Carbon, Alloys, Electrodes, High temperature
Keywords:
Corrosion-resistant coating, multielectrode sensor, corrosion monitoring, acidic solution, caustic solution, high-temperature corrosion sensor, coupled multielectrode, nuclear plant corrosion
© 2008 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).
2008
Association for Materials Protection and Performance (AMPP)
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