Evaluation of Thermally Nitrided Metallic Bipolar Plates for PEM Fuel Cells

摘要

Thermal nitridation of model Ni-Cr base alloys was explored as a means of forming a protective surface nitride layer to permit use as bipolar plates in PEM fuel cells. Thermally grown CrN/Cr_2N layers exhibited excellent corrosion behavior in anodic polarization screening studies in aerated pH3 sulfuric acid at 80℃, with corrosion current densities of less than 1x10~(-6) A/cm~2 up to ～900mV (SHE). Interfacial contact resistance measurements indicated that the nitrided layer yielded 20 mOhm-cm~2 at a compaction load of only ～100 N/cm~2, significantly lower than the initial metalllic (not nitrided) surface. Long-term corrosion studies and in-cell testing are in progress; the results of these efforts will be presented at the conference.