Four ceramic materials (three silicon carbides and one silicon carbide particle-strengthened alumina composite) were corrosion tested to assess their suitability for application as tubes for a steam-methane reformer. Corrosion tests were conducted in simulated reformer atmospheres at temperatures in the range 595 to 1040°C. The fragmented, non-adherent oxide layer (cristobalite) that formed on SiC ceramics increased in thickness with increasing temperature, steam partial pressure, and exposure time. The SiC-Al2O3 composite also formed a thin reaction zone as SiC particles near the surface oxidized and then reacted with residual aluminum alloy or the alumina matrix, but, unlike the oxide layer on the SiC ceramics, the reaction zone thickness did not increase with exposure time. The strengths of the ceramic materials were measured using four-point flexure tests. Based on the limited data available, none of the materials showed a significant strength change that could be related to exposure temperature or steam partial pressure. For all four materials at 1040°C, the samples with the longest exposure time showed the lowest strength; however, this decrease was probably not statistically significant, given the limited number of samples tested.

Subject
Vapor pressure, Materials, Tubes, Oxide layers, Silicon carbide, Micrography, Partial pressures, Oxide surfaces, Composites, Ceramics, Steam, Voids, Oxidation
Keywords:
methane reformers, steam corrosion, corrosive gas, silicon carbide, silicon carbide/alumina composite, silica layer
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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