Investigation of physical and electrical properties of TiN-coated SS316L as bipolar plate of proton exchange membrane fuel cells

In this research, TiN films were deposited on the SS316L substrate by cathodic arc evaporation technique, to use as bipolar plates in proton exchange membrane fuel cells. The effect of substrate surface roughness and film thickness on the interfacial contact resistance and corrosion properties of the TiN films was investigated. Characterization of deposited films was performed by XRD, XRF, ICR, contact angle, and FESEM equipped with energy-dispersive spectroscopy. Electrochemical and surface properties of deposited films were studied by potentiodynamic scanning, electrochemical impedance spectroscopy, and AFM analysis. It is observed that the surface roughness of the substrate, before deposition, has a significant impact on the final properties of TiN coating, especially when the coating thickness is less than 1.2 µm. All of the coated samples showed better corrosion resistance in comparison to the substrate, and the corrosion current density decreased from 1.65 to 0.16 μA cm–2 when coating thickness increased from 0.6 to 1.5 µm.