The galvanic interaction between metals and carbon fiber/polymer matrix composite degrades not only the metals but the composite itself. The objective of this study was to investigate if the fiber type influenced either the mechanism or form of damage. Three different composites were examined. All have same epoxy matrix, 3501-6 epoxy, but contain different carbon fibers, AS4, IM6 and IM7. The surfaces of the composite materials were exposed to 0.5 N NaCl solution to simulate sea water at open circuit condition or cathodic potentials to simulate galvanic coupling of metals. Electrochemical impedance spectroscopy (EIS) was employed to monitor changes in the behavior of the composites. Modeling of experimental data indicated that the parameter, Rp, representing the polymer resistance decreased with increasing time of exposure for both open circuit conditions and applied cathodic potentials. The value of Rp also decreased with increasingly cathodic applied potentials. This suggested that a damage process for the polymer involving increased access of solution to the carbon fibers was operating. SEM examination showed the presence of cracks and polymer separations on the exposed but not on the unexposed surfaces. The fiber type did not appear to influence the damage mechanism in this study but did effect the rate of damage accumulation.

Subject
Materials, Impedance, Open circuits, Material degradation, Polymers, Experimental data, Interfaces, Composites, Fibers, Carbon fiber, Blistering, Damage, Electrolytes
Keywords:
composite, impedance, damage, sodium chloride, fiber type
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
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