Polylaminate TaN/Ta coating modified ferritic stainless steel bipolar plate for high temperature proton exchange membrane fuel cell

A polylaminate coating with intersecting tantalum and tantalum nitride (TaN/Ta/TaN/Ta/TaN/Ta, TaN is the outermost layer) is deposited on surface of 430 stainless steel bipolar plate for high temperature proton exchange membrane fuel cell by a reactive magnetron sputtering method. Electrochemical tests including potentiodynamic, potentiostatic polarisation and electrochemical impedance spectroscopy, are carried out to evaluate the corrosion resistance and stability of the polylaminate TaN/Ta coating in simulating high temperature proton exchange membrane fuel cell environments (85% H 3 PO 4 solution at 80 °C and 130 °C). Results show that the polylaminate TaN/Ta coating greatly improve the corrosion resistance of 430 stainless steel, which can provide almost 100% protection of the substrate in both high temperature proton exchange membrane fuel cell anode and cathode environment. Besides, the interfacial contact resistance of coated 430 stainless steel (9.03 mΩ cm 2 ) is much lower than that of bare substrate (106.74 mΩ cm 2 ). Furthermore, different from the highly increased interfacial contact resistance of bare specimen, the coated 430 stainless steel shows a minor increase resistance after potentiostatic tests in 85% H 3 PO 4 solution at 130 °C.