The reduction of oxygen on rotating ring electrodes made of AISI 420 and AISI 316 stainless steels has been studied in NaCl and Na2SO4 solutions near neutral pH (6 to 10). The reduction rate is strongly dependent on the condition of the surface (specimen preparation and type of oxide), composition of the alloy, and on solution pH, but not on the rotation rate. Reaction rates on AISI 316 SS are approximately half those measure on AISI 420 SS, and much lower than on noble metal electrodes under the same conditions. Little hydrogen peroxide is formed, indicating a strong predominance of the 4-electron reduction path from O2 to HO-. According to the proposed reaction mechanism, the reduction of oxygen, and of other oxyanions, on oxide-covered electrodes is mediated by reduction processes on metal centers in the oxide. The implications of this model for the corrosion and the cathodic protection of corrosion resistant alloys in seawater, and the possible effect of microbial activity on corrosion rates are discussed.

Subject
Electric current, Corrosion rate, Hydrogen peroxide, Electrochemical reactions, Metal oxides, Negative potentials, Oxygen, Stainless steel, Risk reduction, Chemical reactions, Electrodes, Corrosion potential, Electrode potential
Keywords:
oxygen, corrosion, flow, rotating electrode, mass transfer, cathodic protection, stainless steel
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.