It has been known for some time that electrochemical measurements are non-predictive in inhibited concentrated hydrochloric acid at high temperatures. Extensive investigations into the wt. loss to L.P.-rate ratio (R) have shown the latter to be very sensitive to the chemical nature of the inhibitor as well as time dependent. R can vary from 1 to 7 for different inhibitors and/or over a 24 hour time period for the same inhibitor.

A corrosion inhibition mechanism is proposed as a model which explains the behavior of R in terms of water diffusion across a hydrophobic inhibitor barrier. Some consequences of this model bear on the effects of the metallurgy on inhibitor effectiveness, and rationalize the occurrence of pitting on some steels while absent on others. Small amplitude polarization measurements can therefore be used effectively in inhibitor studies even if the classical assumptions of linearity and Tafel behavior are not fulfilled.

Subject
Films, Water, Corrosion rate, Metal surfaces, Inhibitor films, Corrosion attacks, Chemical inhibition, Metals, Weight loss, Corrosion inhibitors, Steel, Pitting, Electrodes
© 1986 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).
1986
Association for Materials Protection and Performance (AMPP)
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