In the alternating voltage passivation process (AVPP) a potential square wave is applied for a certain length of time at a constant dc bias potential. The effects of the process parameters dc bias potential Eo, pulse length P, pulse amplitude A and ratio Ro of the duration of the anodic to the cathodic portion of the pulse on the passive properties of 304 SS have been evaluated using a factorial design experiment. The surface properties have been evaluated by recording anodic polarization curves in 0.1 M H2SO4 from which the critical current density icrit and the passive current density ip were determined. These polarization curves were measured after open-circuit potential decay experiments from which the time tp for open-circuit potential decay was determined. The Flade-potential was independent of the choice of process parameters. For Eo = 300 mV, P = 90 ms, A = 1050 mV and Ro = 4 : 1 an increase of tp by about 130 with respect to the as-received sample has been observed, while icrit decreased by a factor of 100. A significant decrease of ip was also noted.

Subject
Stability, Anode potential, Passive films, Oxide layers, Anodic polarization curves, Waves, Polarization curves, Experimental data, Surface layers, Electric potential, Passivation, Corrosion resistance, Stainless steel
Keywords:
alternating voltage, passivation, surface modification, stainless steel, polarization curves, factorial design
© 1994 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).
1994
Association for Materials Protection and Performance (AMPP)
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