Passive metals and alloys depend on the durability of passive oxide films for high corrosion resistance. This paper discusses the durability of the passive film on alloy 22 (a Ni-Cr-Mo alloy) as a function of chemical, thermal and mechanical durability. The durability of the passive film on alloy 22 was compared and contrasted with that of a corrosion resistant, iron-based structurally amorphous alloy, SAM1651 and with less corrosion resistant alloys such as 316L SS and AL6XN. The chemical and thermal durability were determined by the breakdown and repassivation response of the passive film and by the ability of the passive film to stifle the corrosion after initiation of severe localized corrosion. The mechanical durability of passive films was studied by examining their reformation behavior after scribing the passive film with a diamond tip. The passive film on alloy 22 showed excellent durability under aggressive conditions accompanying a detrimental chemical environment, high temperature and mechanical damage.

Subject
Anode potential, Corrosion resistant alloys, Passive current, Passive films, Repassivation potentials, Sodium chloride, Crevices, Corrosion resistance, Localized corrosion, Alloys, Potentiodynamic polarization, Durability, Breakdown potential
Keywords:
Passive Films, Chemical Durability, Thermal Durability, Mechanical Durability, Alloy 22
© 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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