Effect of surface conditions and determination methods on the corrosion, pit nucleation and critical pitting potentials were examined for zirconiun in a chloride environment. Mill annealed, silicon carbide abraded, chemically polished, electropolished and vacuum annealed surfaces were studied. The most reproducible realistic corrosion potential values were found using electrodes with a silicon carbide abraded surface. The corrosion potential was determined by monitoring the open-circuit potential until equilibrium was established. The pit nucleation potential was determined by potentiodynamic, potentiostep and potentiostatic test methods. The critical pitting potential was determined by a potential back-step and scratch test method. Potentiostatic-scratch and potential back-step test methods yielded identical pitting potentials implying that for zirconium the pit nucleation potential and critical pitting potential are identical. The potentiodynamic and potentiostep test methods yielded much more noble pit nucleation potentials which were surface treatment and scan rate dependent.

Subject
Pits, Zirconium, Repassivation potentials, Nucleation, Surface treatments, Current densities, Pitting, Potassium chloride, Critical pitting potential, Steel grit, Electrodes, Corrosion potential, Electrode potential
© 1981 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).
1981
Association for Materials Protection and Performance (AMPP)
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