2019 Volume 68 Issue 6 Pages 143-147
In expectation of nano-scale nitride layer formation, type 445J1 stainless steels with different grain sizes were cathodically charged in nitric acid-nitrate solution (ECN treatment) and evaluated in terms of interfacial contact resistance against carbon paper (ICR), anodic polarization behavior, chemical state of the surface and PEFC performance in use as bipolar plates. The ECN treatment reduced ICR with more pronounced effect for the stainless steel with finer grains. Polarization test revealed that corrosion resistance was not degraded by the ECN treatment. XPS analysis proved formation of nitride layer on the surface of the stainless steel. The nitride layer was thicker and more stable against anodic polarization for the stainless steel with finer grains. The ECN treatment was applied to the fine-grained stainless steel for use as bipolar plates. The cell performance was comparable to that with graphite bipolar plates, proving that the ECN treated type 445J1 stainless steel with fine grains is a promising candidate material for PEFC bipolar plates.