The catalytic response and durability of noble metal coatings were studied by measuring the corrosion potentials in 288°C water containing oxygen and hydrogen. Catalytic surfaces were created on stainless steel by in-situ exposure to 288°C water containing dissolved noble metals. Auger electron microscopy (AES) data showed a noble metal concentration of about 2-3 at.% on the surface and to a depth of about 400Å, although other analytical techniques showed that this profile resulted from a thin coating of pure metal on a topologically complex surface. In-situ noble metal deposition on stainless steel resulted in the electrochemcial corrosion potential (ECP) well below -230m Vshe under stoichiometric excess hydrogen. The durability of the catalytic surface was also evaluated by measuring the noble metal concentration and corrosion potential of specimens after exposure in an ultrasonic cleaning bath for 1 week in 60°C water and during extended exposure at high flow rate in 288°C water. It was observed that for some noble metal coatings the ultrasonic and high flow exposure caused some loss of noble metals and thereby shifted the corrosion potential in the positive direction.

Subject
Water depth, Water, Coatings, Corrosion rate, Metal surfaces, Noble metals, Water flow, Water chemistry, Molar ratio, Electrodes, Corrosion potential, Durability, Hydrogen
Keywords:
corrosion potential, catalytic property, 304 SS, noble metals, high temperature water, boiling water reactor
© 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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