Corrosion resistant and conductive TiN/TiAlN multilayer coating on 316L SS: a promising metallic bipolar plate for proton exchange membrane fuel cell

The single layers of TiN, TiAlN and TiN/TiAlN multilayer coatings were deposited on 316L SS bipolar plate by physical vapor deposition technique. The X-ray diffraction studies revealed that the formed coatings exhibited single-phase cubic structure. The low surface roughness and high contact angles of the TiAlN and TiN/TiAlN coatings governed the better water management in the fuel cell. Nyquist and Bode-impedance studies of TiN/TiAlN coating ensured higher electrochemical impedance behavior. The polarization results revealed that the current densities (i(corr)) of TiN/TiAlN coating were below 1 mu A/cm(2) in the PEMFC environments, which satisfied the U.S. Department of Energy's 2020 target. The contact resistance of the TiN/TiAlN-coated 316L SS was the lowest and fulfilled the requirements of bipolar plate (<= 10 m ohm cm(2)) in PEMFC environment. Surface morphology results revealed that the surface of 316L SS is well protected by multilayer TiN/TiAlN coating. Inductive coupled plasma-optical emission spectroscopy results are in good agreement with electrochemical studies revealing the TiN/TiAlN coating significantly reduced the metal ions dissolution.

Automated summary

The single layers of TiN, TiAlN and TiN/TiAlN multilayer coatings were deposited on 316L SS bipolar plate by physical vapor deposition technique. Studies showed that TiN/TiAlN coating exhibited better water management and higher electrochemical impedance behavior in the fuel cell, even meeting the U.S. Department of Energy's 2020 target, and significantly reducing the metal ions dissolution.