Electrochemical studies on TiN and ZrN coated stainless steels suggested a protection mechanism by formation of protective passive films. Increased coating thickness was shown by cyclic polarization tests to increase the breakdown potential of the coatings to near or higher than titanium and zirconium metal in the same solution. A multilayer TiN/Ti/TiN coating was shown as an alternative to improve both the resistance to charge transfer and increase the breakdown potential to more noble potential. The latter can also be achieved by multilayer ZrN/Zr/ZrN coatings. The high charge transfer resistance of zirconium nitride when compared to titanium nitride supported results from a previous study (16) and contributed to a lower current density for film formation of approximately 10-3 μA/cm2. The passive region on these coatings was characterized by a small increased in current with increasing potential and called "pseudo-passive" region.

Subject
Coatings, Substrates, Tin, Oxide formation, Saturation, Passive films, Oxide films, Free corrosion potential, Current densities, Film formation, Titanium, Coating defects, Polarization resistance
Keywords:
titanium nitride, zirconium nitride, multilayer coating, impedance spectroscopy, cyclic polarization, polarization resistance, passive films
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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