The corrosion behaviour of commercially available lead and aluminium alloy tubes and rods has been studied for a period of 2 years in the tropical marine environment of Mandapam. The monthly and quarterly corrosion rate values of the alloys are directly related to and determined by the weathering conditions, such as salt content in the air, percentage relative humidity, temperature and rainfall, prevailing during a particular monsoon. The exponential decrease in the corrosion rate values of the cumulative exposures of the alloys, in general, are indicative of the protective nature of the corrosion product film on its surface. The corrosion products on lead and aluminium alloys are analysed with X-ray diffractometer. Formation of Lead chloride on the monthly exposure surfaces lead to uniform corrosion attack, whereas formation of lead oxychloride and antimony oxychloride on cumulative exposure surfaces of lead result in localised pitting- Formation of Al2O3, A1(0H)3, AlCl3.6H20 and AlO(OH) on the surfaces of the aluminium alloys influences the pitting corrosion over the period of exposure. The pitting corrosion behaviour of lead and aluminium alloys are discussed in the light of pit density, pitting probability and size of pit. The surface characteristics of lead over the period of exposure are highlighted with scanning electron microscope. Heterogeneity in the aluminium alloy matrix favour pitting and intergranular corrosion.

Subject
Pits, Marine environments, Corrosion rate, Metal surfaces, Aluminum, Tubes, Rods, Lead, Corrosion products, Corrosion attacks, Corrosion behavior, Pitting, Aluminum alloys
Keywords:
Marine corrosion, environmental conditions, lead, aluminium alloy tubes & rods, corrosion products, pitting, intergranular corrosion
© 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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