In CO-rich coal gasification atmospheres, sulfidation attack of metallic components can cause severe wastage problems. In these highly reducing environments, Si is one of the elements with a high enough affinity for oxygen to enable a silica-rich scale to be formed which may provide reasonable protection of the alloy substrate. In this study, the corrosion behavior of a commercial 12%Cr ferritic alloy is compared with the resistance of a series of specially cast 12%Cr and 12%Cr-12%Ni “model” alloys having Si levels ranging from 1.3 to 4 %. Two higher Cr-Ni austenitic alloys (25%Cr-20%Ni and 20%Cr-32%Ni) have also been tested. Coupons from each material have been exposed to a non-equilibrated CO-based gas mixture containing 0.8 % H2S for up to 2000 hours. Weight changes and surface and cross-sectional examinations have been used to measure the kinetics and establish the morphology, type and extent of corrosive degradation.

Subject
Materials, Corrosion resistant alloys, Composition, Nickel based alloys, Metal loss, Commercial alloys, Corrosion scales, Corrosion modeling, Scale formation, Wet gas, Scale, Corrosion resistance, Alloys
Keywords:
Corrosion, sulfide scales, Si additions, 12 %Cr alloys, non-equilibrated CO-rich gases
© 1997 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).
1997
Association for Materials Protection and Performance (AMPP)
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