The formation of protective nitride surfaces for PEM fuel cell metallic bipolar plates

摘要

The selective gas nitridation of model nickel-based alloys was used to form dense, electrically conductive and corrosion-resistant nitride surface layers, including TiN, VN, CrN, Cr2N, as wellas a complex NiNbVN phase. Evaluation for use as a protective surface for metallic bipolar plates in proton exchange membrane fuel cells (PEMFC) indicated that CrN/Cr2N based surfaces holdpromise to meet U.S. Department of Energy (DOE) performance goals for automative applications. The thermally grown CrN/Cr2N surface formed on model Ni−Cr based alloys exhibited good stability and low electrical resistance in single-cell fuel cell testing under simulated drive-cycle conditions. Recent results indicate that similar protective chromium nitride surfaces can be formed on less expensive Fe−Cr based alloys potentially capable of meeting DOE cost goals.