Preferential thermal nitridation to form pin-hole free Cr-nitrides to protect proton exchange membrane fuel cell metallic bipolar plates

Preferential thermal nitridation was used to form a pin-hole defect free CrN/Cr2N surface on a model Ni-Cr alloy. Excellent corrosion resistance and negligible contact resistance increase was observed over a 4100 h exposure in 80 degreesC sulfuric acid and when used as a metallic bipolar plate in a 1000 h proton exchange membrane (PEM) fuel cell test. (C) 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.