Corrosion inhibitors such as Volatile Corrosion Inhibitors (VCI's) and Contact Corrosion Inhibitors have become loosely ambiguous and differentiating between the two can become a gray area. For example, and the most common mistake is, classifying a material as a VCI when it is a contact inhibitor. Analytical techniques to qualify a material as a VCI have been investigated in order to clarify this ambiguity and to qualify the techniques and equipment for use in the determination of a VCI. The Quartz Crystal Microbalance (QCM) and an atmospheric corrosion monitor were used to characterize adsorption effects and corrosion monitoring of two commercially known inhibitors, sodium nitrite and dicyclohexylammonium nitrite on evaporated iron during atmospheric conditions.

Two devices will be used for in situ measurements of adsorption, the QCM and an atmospheric corrosion monitor. During the adsorption process the QCM measures a frequency change that can be associated to a mass change due to adsorption of the inhibitor it is also capable of in situ monitoring corrosion rates of the substrate in a corrosive atmosphere. From experience and in theory the corrosion rate is expected to decrease due to the adsorption of the VCI. Which has been observed from in situ measurements using the QCM.3,6,7  The atmospheric corrosion monitor measures the resistance of oxides of a substrate due to corrosion in reference to a non corrosive element. It is tested here to measure its sensitivity in comparison to the QCM and to characterize its response during the adsorption of a VCI.

Subject
Atmospheric corrosion, Sensors, Materials, Sodium nitrite, Substrates, Adsorption, Volatile corrosion inhibitors, Quartz, Nitrogen, Corrosion inhibitors, Equipment, Corrosion resistance, Corrosion monitoring
Keywords:
Quartz Crystal Microbalance, QCM, atmospheric corrosion monitor, sodium nitrite, dicyclohexylammonium nitrite, dichan, adsorption, Volatile Corrosion Inhibitor, VCI, contact corrosion inhibitor
© 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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