The effects of various pre-oxidation treatments on the Type II (i.e., 700°C) hot corrosion resistance of novel Pt+Hf-modified γ′-Ni3Al + γ-Ni alloys and coatings were studied and compared to a state-of-the-art Pt-modified β-NiAl coating. The pre-oxidation treatments were carried out in air and in Ar atmospheres at temperatures of 700, 1080, and 1100°C and for times of 1, 6, and 24h. It was found that pre-oxidation in air at higher temperatures and for a shorter period was quite beneficial in improving hot corrosion resistance of the Pt+Hf-modified γ′ + γ alloys and coatings. In fact, the results suggested that the oxide scale formed with such a treatment was much more protective than the Ar and longer-term air pre-oxidation treatments. It was also found that with an optimum pre-oxidation treatment, a Pt+Hf-modified γ′+γ coating exhibited superior hot corrosion resistance compared to a Pt-modified β coating.

Subject
Hot corrosion, Test methods, Coatings, Corrosion resistant alloys, Salts, Nickel based alloys, Micrography, Weight gain, Corrosion attacks, Oxide scales, Scale formation, Corrosion resistance, Samples
Keywords:
Type II hot corrosion, pre-oxidation, Pt+Hf-modified γ′-Ni3Al + γ-Ni alloys and coatings, Pt-modified β-NiAl coating
© 2007 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).
2007
Association for Materials Protection and Performance (AMPP)
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