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 -0.1 V vs SCE purged with H-2 and the simulated cathode environment was 0.6 V vs SCE purged with O-2. 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. (c) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.