Enhanced corrosion resistance and fuel cell performance of Al1050 bipolar plate coated with TiN/Ti double layer

In this study, we investigated the effects of TiN/Ti and TiO2/Ti double layer coatings, with a metal buffer layer, on the corrosion resistance, and electrical properties of Al1050 substrates for using them as bipolar plates in PEMFCs. TiN/Ti and TiO2/Ti double layers were deposited using the electromagnetic-field-superpositioned DC and RF magnetron sputtering method. The surface resistivity and contact resistance of the specimens were measured using the van der Pauw method and a previously reported interfacial contact resistance (ICR) measurement method, respectively. Further, the corrosion resistance of the specimens was characterized using electrochemical tests such as potentiodynamic and potentiostatic polarization tests. The results obtained in this study indicated that coating of the Al1050 substrates significantly increased the corrosion resistance of bipolar plates in the operating environment of a fuel cell when compared to uncoated substrates. In particular, the substrate coated with a TiN/Ti double layer exhibited the best performance: its corrosion current density was 30 times lower than that of an uncoated substrate under anodic conditions. Further, the Al1050 bipolar plate coated with a TiN/Ti double layer showed performance enhancement over an uncoated bipolar plate in an actual fuel cell test.