Multistep active screen plasma co-alloying the treatment of metallic bipolar plates

Abstract

Active screen plasma (ASP) surface treatments have been widely utilized to improve surface performances of stainless steel in various applications. In our previous research, active screen plasma nitriding (ASPN) and active screen plasma co-alloying processes have been successfully employed to modify 316L stainless steel for the application of proton exchange membrane (PEM) fuel cell bipolar plates. In this study, a multistep active screen plasma co-alloying surface treatment with niobium and nitrogen was proposed to produce a tailored layer structure on the surface of 316L stainless steel. By tailoring the applied bias of step, single-layer and duplex-layer structures can be formed on the surface of 316L stainless steel. Performance tests showed that the sample with a duplex-layer structure exhibited improved interfacial contact conductivity and higher corrosion potential than the sample with a single-layer structure, indicating the feasibility of this multistep active screen plasma co-alloying surface treatment for PEM fuel cell bipolar plate application.