The thermal spray coating technique was applied to produce the catalytic or insulated protective coatings on 304 stainless steel (SS) surface. The electrochemical corrosion potential (ECP) response of such coatings in high temperature water under various water chemistry conditions were evaluated. The ECP results clearly demonstrated that the catalytic coatings (CC) produced with various alloy powders containing small amounts of Pd responded fully catalytically in the presence of the stoichiometric excess hydrogen, showing a ECP value well below the intergranular stress corrosion cracking (IGSCC) protection potential (-230 mVshe). Furthermore, the insulated protective coating (IPC) layer created with a powder of yttria-stabilized zirconia (YSZ) restricted the oxidant transport rate to the metal surface, and the ECP remained at <-500 mVshe in 288°C water containing to 200-300 ppb oxygen (O2) and no hydrogen (H2).

Subject
Water, Intergranular stress corrosion cracking, Boiling water reactors, Hydrogen concentration, Metal surfaces, Water chemistry, Oxidants, Powders, Oxygen, Electrodes, Thermal spray coatings, Hydrogen, High temperature
Keywords:
ECP, IGSCC, catalytic or insulated coatings, boiling water reactor, noble metal, zirconia, high temperature water, HVOF, plasma spray
© 1998 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).
1998
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.