不锈钢双极板低温等离子氮化后的性能

Performance of Low Temperature Plasma-Assisted Nltrlding Layer on Stainless Steel Bipolar Plates

为了减轻质子交换膜燃料电池(PEMFC)的质量,降低其生产成本,实现其商业化,以不锈钢取代传统的双极板材料石墨,对304不锈钢进行低温等离子氮化,研究了氮化后的不锈钢在模拟PEMFC环境中的电化学腐蚀行为以及在电池工作电位下的接触电阻。结果表明:在低温等离子渗氮过程中不锈钢表面生成了面心立方结构的氮过饱和固溶体(γN相)氮化层,一定程度上改善了不锈钢在模拟PEMFC环境中的耐均匀腐蚀能力;以PEMFC工位电位恒电位极化时,氮化后的不锈钢表面生成了稳定的钝化膜,通入O2更易于使氮化后的不锈钢钝化;氮化后的304不锈钢的表面接触电阻远低于基体,电化学性能和电性能接近于石墨双极板,基本能满足PEMFC双极板的使用要求。

Cailiao Baohu 2010,43(10),65～67(Ch).304 stainless steel was adopted to replace conventional bipolar material graphite for the purpose of reducing the mass and cost of polymer electrolyte membrane fuel cell(PEMFC) and realizing the industrialization.The stainless steel was modified by low temperature plasma-assisted nitriding.The electrochemical corrosion behavior of the nitrided stainless steel in simulated PEMFC environment and its contact resistance under working potential of cell were investigated.It was found that after low temperature plasma-assisted nitriding,N-saturated solid solution(γ-N phase) with face cubic structure was formed on the surface of the stainless steel,leading to increased corrosion resistance in simulated PEMFC environment.During polarization at constant potential,a stable passivation film was formed on the surface of the nitrided stainless steel,and introduction of O2 promoted the passivation.Besides,the contact resistance of the nitrided stainless steel was much lower than that of the steel substrate,and its electrochemical and electrical performances were comparable to those of graphite bipolar plates,meeting with the requirements for PEMFC bipolar plates.