Study on Corrosion Resistance and Conductivity of TiMoN Coatings with Different Mo Contents under Simulated PEMFC Cathode Environment

TiMoN coatings with different Mo contents on a SS316L substrate are deposited by using closed field unbalanced magnetron sputtering ion plating (CFUMSIP) technology to enhance the corrosion resistance and durability of stainless steel (SS) bipolar plates (BPs) in proton exchange membrane fuel cell (PEMFC) during the start-up/shut-down process. The electrochemical test results illustrate that TiMoN-4A coating has extremely good corrosion resistance compared to other coatings. The potentiostat polarization (+0.6 V(SCE)) tests indicate that the corrosion current density (I(corr)) of TiMoN-4A coating is 5.22 × 10(−7)A cm(−2), which meets the department of energy 2020 targets (DOE, ≤1 × 10(−6) A cm(−2)). Otherwise, TiMoN-4A coating also exhibits the best corrosion resistance and stability in potentiostatic polarization, electrochemical impedance spectroscopy (EIS), and high potential (+1.2V(SCE)) polarization tests. The interfacial contact resistance (ICR) measurement results show that TiMoN-4A coating has the minimum ICR of 9.19 mΩ·cm(2), which meets the DOE 2020 targets (≤10 mΩ·cm(2)).