Zinc phosphating is widely used in industrial coating applications as surface pretreatments for the painting of metals. In car industry, this conversion coating process is applied as well on coated products (zinc electrocoated or hot dip galvanized steel) as on bare steel. It results in the formation of a densely packed crystals layer of phosphophyllite (mixed Zn Fe phosphate) on bare steel and of hopeite (Zn phosphate) on coated products. The phosphate layer formed on a carbody undergoes different aggressions: thermal aggressions during paint baking and chemical aggressions during cathodic electrodeposition of paint coating and during car service. The present work aims to define the thermal and chemical stability of phosphate layers during cataphoretic paint and baking simulations and after immersion in different buffers ranging from pH 1 to 14. The last results are compared with analyses of phosphate layers of painted panels that have undergone corrosion tests.

Subject
Films, Zinc nickel coatings, Zinc rich coatings, Water, Modeling, Baking, Acidity, Phosphates, Weight loss, Steel, Immersion, Zinc, Paints
© 1988 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).
1988
Association for Materials Protection and Performance (AMPP)
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