Recent evidence indicates that ferrous carbonate (FeCO3, siderite) plays a critical role in forming corrosion resistant scale. The temperature dependent precipitation kinetics of ferrous carbonate were studied using a powerful new "temperature ramped" approach. The activation energy calculated using a second order precipitation model (123 kJ/mol) qualitatively indicates that precipitation was controlled by surface reaction rate over the temperature interval studied. At low temperatures (<60 C), precipitation is expected to progress more slowly than corrosion reactions. At elevated temperatures (>175 C), transport limited ferrous carbonate deposition should be limited by the corrosion reaction. Corroding surfaces may be immediately passivated by FeCO3 precipitation at high temperature. At intermediate temperatures, ferrous carbonate may drive the corrosion reaction by removing iron from solution at approximately the same rate as it is provided by corrosion. The techniques developed in this research could easily be adapted for use with a number of other reduced metal systems.

Subject
Water, Materials, Precipitation (solids), Corrosion rate, Metal surfaces, Reactors, Iron, Solubility, Corrosion reactions, Siderite, Constants, Experimental data, Kinetics
© 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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