Effect of alloying elements on the contact resistance and the passivation behaviour of stainless steels

• Published in: Corrosion science Vol. 44; no. 4; pp. 635 - 655
• Main Authors: Kim, J.S, Peelen, W.H.A, Hemmes, K, Makkus, R.C
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2002
• Subjects: Bi-polar plate; Chromium; Contact electric resistance; Molybdenum; Passivation; Passive films; Pitting resistance equivalent number; Polymer electrolyte membrane fuel cell; Stainless steels; Transpassive transition; Passive films; Polymer electrolyte membrane fuel cell; Bi-polar plate; Contact electric resistance; Chromium; Pitting resistance equivalent number; Molybdenum; Stainless steels; Transpassive transition; Passivation
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/S0010-938X(01)00107-X

The effects of alloying elements (Cr, Mo) on the passivation and the transpassive transition behaviour of various commercial stainless steels, which are candidate materials for the bi-polar plates in polymer electrolyte membrane fuel cell, were investigated via a contact electric resistance (CER) technique with graphite counter part. The contact resistance, too high for a semi-conductor film with high donor density, is not the inherent ohmic resistance of the passive film. The CER potentials decrease linearly with the pitting resistance equivalent number (PREN). The passive films of stainless steels with high PREN are more readily removed compared to those with low PREN in terms of the charge necessary to remove the passive films. The change in transpassive transition behaviour of the stainless steels from that of iron to that of chromium went on steeply with an increase in the PREN.