Bipolar plate bare plates

Hdi Wang and John A. Turner Introduction 361 Metallic Bipolar Plates 363 Bare Metallic Bipolar Plates 363 Light Alloys 366... 

Stainless steels, as well as A1-, Ni-, and Ti-based alloys have been studied extensively as possible candidates for bipolar plates. One of the most well-studied materials for bipolar plates is SS 316/316L (16-18% Cr, 10-14% Ni, 2% Mo, rest Fe) other candidates are 310,904L, 446, and 2205. Bare stainless steel plates form a passive 2-A nm chromium oxide surface layer under PEMFC conditiOTs that leads to unacceptably high ICRs. A similar trend is observed for the other alloys and therefore surface modification or surface coatings on selected substrate material has to be considered as a pathway to meet the technical targets of low ICR and high corrosion resistance. 

Although it is a matter of common knowledge that stainless steel is quite prone to corrosion in fuel cells, bare substrates of different alloys were tested in past material investigations. In 1998, Hornung and Kappelt (1998) selected different iron-based materials for Solid Polymer Fuel Cell bipolar plates by using the pitting resistance equivalent (PRE = %Cr + 3.3%Mo + 30%N) as corrosion resistance criterion. The authors exposed that some iron-based materials with PRE >25 (the material compositions are not given... 

Today, uncoated stainless-steel materials are still in focus of research, as bare substrates promise to be the most cost-effective solution for metal bipolar plates. Nevertheless, it becomes obvious that a surface modification method or protective coating applied to metal bipolar plates is essential to improve their corrosion resistance. 

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