Surface properties of stainless steel cathodically treated in nitrate solution and its application to PEFC bipolar plates

摘要

Type 310S stainless steel cathodically treated in a nitric acid - nitrate solution in anticipation of formation of conductive nitrides has been evaluated in terms of contact resistance against gas dif fusion layer(GDL), polarization behavior, surface chemical state and PEFC performance when used as bipolar plate. The contact resistance between the treated stainless steel and GDL did decrease to the demanded level. XPS analysis indicated formation of thin nitride layer on stainless steel among oxides. The thickness of the nitride layer was within a few nanometers but was stable even after anodic polarization at 0.6 V vs. SCE. The cathodic treatment was applied to stainless steel bipolar plates for operation of a single cell. The cell performance was comparable to that with graphite bipolar plates, suggesting great promise as a convenient surface treatment for stainless steel bipolar plates.