Effects of PVD deposition method on electrochemical properties and interfacial contact resistance of CrN coated titanium as PEMFC bipolar plate

ABSTRACT In this research, CrN coating was applied to grade 1 titanium as a bipolar plate for PEMFC. The CrN was deposited by ion beam assisted deposition (IBAD) and the arc ion plating method (AIP). The thickness of the coating layer was about 2.5∼3 μm and it was densely deposited on the titanium substrate. The electrochemical experiments were conducted in an aqueous solution of pH 3 (H2SO4 + 0.1 ppm HF, 80°C) determined by DoE. Hydrogen gas and air were bubbled to simulate the anode and cathode environments, respectively. Various analyses (XRD, EDS, FE-SEM), electrochemical experiments (EIS, potentiodynamic polarisation, potentiostatic experiment), and interfacial contact resistance measurement were performed to evaluate the effects of the PVD deposition method. Due to the difference in the PVD method, CrN and Cr2N were formed in the IBAD specimen, whereas CrN phase was observed in the AIP specimen. The CrN coated specimens presented improved interfacial contact resistance compared to the titanium substrate.