A number of years ago our group coined the phrase 'natural passivation' to describe the highly structured, oxide dominated, thin film that grows in air at relatively low temperatures on the surface of most metals, and provides a barrier to future, corrosive attack. In the present study the nature of that film is described, with particular attention paid to the changes in oxidation state and the terminal hydroxide layer formed. We also point out that alloys are subject to natural passivation, with the additional feature of selective segregations and oxidations. Distinct examples are described of how these processes may in some cases impede and in other cases assist corrosion. Further study has established that semiconductors, and even purportedly inert polymers, are subject to very similar forms of thin film, oxide, natural passivation, and subsequent corrosive attack. In fact, we suggest that all solid surfaces, even biological entities, exhibit some form of natural passivation, and this may play an influential role in our environment. We also describe the impact of these processes on the integrity of the new high Tc oxide super-conductors, and also on the behavior of model catalytic systems.

Subject
External surfaces, Materials, Hydroxides, Oxides, Metal surfaces, Oxide formation, Oxide layers, Metal oxides, X-ray spectroscopy, Oxide surfaces, Metals, Passivation, Oxidation
© 1990 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).
1990
Association for Materials Protection and Performance (AMPP)
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