In situ Raman spectroscopy, surface enhanced Raman spectroscopy, scanning electron microscopy and measurements of corrosion potential were used to investigate the films formed on iron in 288°C water with dissolved oxygen concentrations that ranged from 0 to 208 ppb. A double layer film of Fe3O4 that consists of an inner, conformal layer and an outer layer of faceted, loosely packed particles forms in water containing 0 to 22 ppb oxygen. Passivation of the iron surface begins at dissolved oxygen concentrations of ≈ 8 ppb and is a two step process: first, between 8 and 22 ppb oxygen, there is an increase in protectiveness of the Fe3O4 and second, between 22 and 53 ppb the outer surface of Fe3O4 transforms to α-Fe2O3, which completes passivation.

Subject
Scanning electron microscopy, Films, Water, Metal surfaces, Autoclaves, Iron, Micrography, Interfaces, Film formation, Gold, Oxygen, Dissolved oxygen, Corrosion potential
Keywords:
Oxidation, Raman Spectroscopy, Sers, Iron, Passive Film
© 2001 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).
2001
Association for Materials Protection and Performance (AMPP)
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