Proton exchange membrane (PEM) fuel cell bipolar plates prepared from a physical vapor deposition (PVD) titanium nitride (TiN) coated AISI416 stainless-steel

Metal nitrides (and particularly TiN) are among the most extensively investigated proton exchange membrane fuel cell bipolar plates (BP) coatings. The most employed methods of nitrides coating deposition are various modifications of physical vapor deposition (PVD), while different types of stainless steels are the most common BP materials coated with TiN PVD films. In the current work, we report on the integrity maintenance of TiN PVD coating of AISI416, considering this as a clue to the sustainability of such a film. The advantage of this combination lies in the fact that the coefficients of thermal expansion (CTE) of this alloy is close to the CTE of the TiN film. Thus, the thermal stresses of such coating are expected to be minimal, as well as related coating cracks. We conducted a thorough surface analysis of roughness evolution in the course of BP corrosion process, investigating different initial surface pretreatments. Finally, we found that fine mirror-like polished BP substrate prior to deposition is essential for TiN film’s integrity during corrosion analysis time.