Tungsten Diffusion Modified AISI 304 Stainless Steel for PEMFC Bipolar Plate

Abstract Plasma surface diffusion alloying method has been applied to prepare a tungsten diffusion modified layer on the surface of AISI 304 stainless steel (W‐304 SS). A series of material evaluation experiments were performed on the W‐304 SS specimens to determine whether it is suitable to be used as PEMFC bipolar plate. Results show that the tungsten modified layer (about 2.5 μm in thickness) is mainly composed of tungsten elements. Potentiodynamic and potentiostatic as well as electrochemical impedance spectroscopy measurements in simulated PEMFC operating conditions of 2 ppm F – and 0.05 M H 2 SO 4 solution at 70 °C bubbling with either air or pure H 2 , suggest that the corrosion resistance and the passivated behavior of the W‐304 SS are improved. Meanwhile, the interfacial contact resistance (ICR) for the as‐received W‐304 SS reduces considerably, which yields better results than those found in untreated specimens.