An investigation of the electrochemical properties of PVD TiN-coated SS410 in simulated PEM fuel cell environments

Bipolar plates are a key component of PEM fuel cells, and they constitute a large portion of the weight and total cost of a fuel cell stack. In order to reduce both the cost and weight of the bipolar plates, considerable attention is being paid to developing metallic bipolar plates to replace non-porous graphite. In this study, TiN was coated on a martensitic stainless steel (SS410) using a PVD technology (plasma enhanced reactive evaporation) to increase the corrosion resistance of the base metal. XRD, SEM, EIS and potentiodynamic tests were used to characterize the TiN-coated SS410. In order to investigate the suitability of these coated materials as the anodes and cathodes in a PEMFC, potentiostatic tests were conducted under both simulated cathode and anode conditions. The simulated anode environment was -0.1V vs SCE purged with H2H2 and the simulated cathode environment was 0.6 V vs SCE purged with O2O2. The dense TiN coatings formed on SS410 much improved the corrosion resistance of SS410 and, thus, these coated materials could potentially be used in PEMFCs as a bipolar plate material provided they also satisfy the other physical and mechanical property requirements such as interfacial contact resistance, light weight, high mechanical strength and manufacturability.