The bipolar plate(BPP) constitutes up to 28% of the PEMFC stack cost[1]. Cheaper and more lightweight materials are needed, while there are strict requirements on both the mechanical and chemical stability within the acidic environment of the fuel cell. The targets set by the US DOE are a corrosion current <1 μA/cm2 and interfacial contact resistance <0.01 ohm cm2[2].

Stainless steel is affordable and has the mechanical stability required for the BPPs. However, SS is subject to corrosion in the PEMFC environment. To be able to reach the DOE goals, either noble metal or conductive ceramic coatings must be utilised[3]. In this work, commercially available coatings on hydroformed SS 316L flow plates are studied. A single cell fuel cell tester is used to age the samples, and the in-situ degradation is measured by impedance measurements and polarisation curves. The electrochemical micro-cell technique is utilised to study the corrosion on both the pristine and aged flow plates by polarisation. SEM is used to analyse the surface. The aim is to better understand the pitting corrosion on PEMFC flow plates.