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

Abstract

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% H3PO4 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 cm2) is much lower than that of bare substrate (106.74 mΩ cm2). 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% H3PO4 solution at 130 °C.