Cyclic potentiodynamic polarization experiments were performed on several Al alloys and on 99.995 w/o Al for the purpose of investigating the composition-exposure-properties interrelationship as applicable to galvanic anode marine cathodic protection applications. Materials included 1) a commercial Al-Zn-In anode that conformed to MIL-A-24799, 2) samples of galvanic Al anodes that were sectioned from an offshore structure, 3) an arc sprayed Al-20Zn-0.2In alloy, and 4) 99.995 percent Al. Emphasis was placed on characterizing the critical pitting and repassivation potentials (Ep and Er, respectively) as a function of scan rate, temperature, surface roughness (including as-cast surfaces), pre-scan potentiostatic conditioning potential and conditioning time, and location of the specimen relative to geometry of the original casting. Statistical analysis of the Ep and Er data suggest that compositional variations within a casting and surface roughness are important factors with regard to galvanic anode performance.

Subject
Materials, Galvanic anodes, Metal surfaces, Passive films, Zinc anodes, Repassivation potentials, Aluminum zinc indium alloys, Roughness, Anode surfaces, Specimen preparation, Pitting, Corrosion potential, Anodes
Keywords:
aluminum anode, activation, seawater, potentiodynamic scan rate, surface roughness, alloying elements, corrosion probability, micro-morphology, cathodic protection
© 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)
You do not currently have access to this content.