Erosion-corrosion arising from aqueous slurry environments can be a significant problem in the oil sands industry. Interactions between erosion and corrosion are complex and as such it is difficult to determine the rate of material loss with sufficient accuracy for reliable prediction of equipment lifetime. One material which has been successfully used on production critical equipment is tungsten carbide (WC) metal matrix composite (MMC) weld overlays.

Four WC-based hardfacings with different particle size distributions were investigated. These overlays were comprised of 65 wt % WC hard phase with a metal matrix binder consisting of mainly Ni, Cr, Si, B and Fe. The Metal Matrix Composites (MMCs) overlays were applied using the plasma transferred arc (PTA) welding process

Electrochemical corrosion tests in a simulated recycle cooling water environment were conducted to investigate the corrosion behaviour of the MMCs. In static corrosion tests, little change in the corrosion rate with different WC grain sizes was observed. The smallest WC grain size distribution did show a slight decrease in corrosion resistance.

Similarly, little difference in erosion-corrosion was recorded for the different WC grain size fractions tested with larger grain sizes showing a slight reduction in erosion-corrosion resistance. The interactions between erosion and corrosion can be identified and are important in the MMC degradation. The corrosion mechanisms in static condition and the erosion-corrosion mechanisms can be directly linked to the complex microstructure of the MMCs.

Subject
Grain size, Water, Materials, Carbides, Microstructure, Nickel based alloys, Binders, Tungsten carbide, Erosion, Corrosion resistance, Erosion corrosion, Anodic polarization, Grain
Keywords:
Erosion-Corrosion, Corrosion, WC, MMC, Hardfacing
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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