The codeposition of chromium and silicon into a 2.25Cr-1.0Mo-0.15C steel, Alloy 800, and 304 stainless steel has been achieved using the pack cementation process. The ferritic coating produced on the 2.25Cr-1.0Mo steel was approximately 225 microns (9 mils) thick, whereas the inward diffusion of chromium and silicon produced a two-phase structure of ferrite and austenite for the 304 stainless steel. Chromium and silicon were incorporated into the austenitic solid solution upon diffusion into Alloy 800. Ail of the coatings had approximately 25-35wt% Cr and 24% Si at the surface. Cyclic oxidation testing in air of the coated 2.25Cr-1.0Mo steel (T=700°C) and 304 stainless steel (T = 1035°C) showed a dramatic decrease in the oxidation kinetics compared to the original uncoated alloys. The cyclic oxidation of Alloy 800 was also improved.

Subject
Steel surfaces, Coatings, Composition, Stainless alloys, Microstructure, Steel coupons, Halides, Sodium chloride, Steel, Surface profile, Alloys, Activators, Oxidation
Keywords:
pack cementation, diffusion coating, cyclic oxidation, halide activator, codeposition
© 1991 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).
1991
Association for Materials Protection and Performance (AMPP)
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