55%Al-Zn and 5%Al-Zn were phosphated in comparison with electrolytic zinc coatings. Potential measurements during phosphating were carried out in order to find the interpretation of differences in the crystal size. Impedance measurements were performed for the assessment of the corrosion properties of the phosphate coatings. It was found that there is no differences between coatings formed from the high or low- zinc baths. The best results were obtained for the phosphated 55%Al-Zn, however one may find also suitable treatment for 5%Al-Zn surface. From the X-ray diffraction data de- and rehydration tendency of the coating components were recorded. In the case of high - zinc processes it was found that the slowest rehydration rate occurs on the phosphated 5%Al - Zn surfaces. It was also found that depending on the kind of the bath, hopeite formed on the metal surface exhibited various thermal stabilities.

Subject
Coated steel, Zinc rich coatings, Steel surfaces, Substrates, Metal surfaces, Impedance, Substrate surfaces, Phosphates, Metals, Steel, Corrosion protection, Zinc, Phosphating
Keywords:
coated steel, alloy coating, phosphating, phosphate coatings, thermal stability, rehydration, protective properties, impedance
© 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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