| Due to low cost, light weight, ease of machining and shaping into thin sheets as well as good in electrical conductivity and heat exchange, stainless steels are considered to be the most promising bipolar plate material for proton exchange membrane fuel cell (PEMFC). However, the interfacial contact resistance (ICR) between the carbon-paper and stainless steel increased because of the formation of the passive film in PEMFC cathode environments, and the corrosion products of the bipolar plate could poison the catalysts and decrease the efficiency of the cell in PEMFC anodic environment.In this paper, we mainly studied two kinds methods that preparing Silver-plating before graphite-coating and CrxN thin films on the surface of 316L stainless steel bipolar plate, and then test their conductive corrosion resistance in simulated PEMFC work environment; In addition, a preliminary study of the main factors that affect the corrosion resistance of modified stainless steel bipolar plates in the PEMFC work environment, and focuses on the effect of F- on the corrosion resistance CrxN film / 316L stainless steel bipolar plates.The result shows that: the method of pre-plating a thin layer of silver, and then prepared graphite coating on the surface of 316L stainless steel can effectively improve the conductive and corrosion resistance of 316L stainless steel bipolar plates in PEMFC working environment, and its contact resistance value with Toray 060 carbon paper as low as 19.03 m?·cm2. In the cathode conditions, the corrosion potential is 0.18 V, the corrosion current is about 5.01×10-7 A·cm-2. In the anode conditions, its potential is about 0.07 V and the corrosion current is 1.58×10-6 A·cm-2. In addition, the Silver-plating and graphite-coating SS-316L showed good hydrophobic properties, its contact angle is 112.03°.Deposited CrxN (Cr0.49N0.51-Cr0.43N0.57) thin film on 316L stainless steel surface by pulsed bias arc ion plating method, the contact resistance values is low as 10.86 m?·cm2, In the cathode conditions, the corrosion potential is -0.12 V, and the corrosion current is 1.02×10-5 A·cm-2. In the condition of anode, the corrosion potential is -0.26 V, the corrosion current is 5.01×10-6 A·cm-2. In addition, the research on its durability shows that: although the decay rate is slow, it still decreases in corrosion resistance with time increasing, and the corrosion resistance becomes worse and worse. How to increase the compactness of thin film of the surface modification specimen and its durability in a acid Solution is still the current main subject.At last, we studied the main factors that impact the corrosion resistance of CrxN thin film/316L stainless steel bipolar plate in a PEMFC working environment. There is a certain positive correlation between the corrosion resistance of CrxN film / 316L stainless steel bipolar plate and temperature or the concentration of sulfuric acid, when temperature or the concentration of sulfuric acid increases, Corrosion resistance of CrxN film / 316L stainless steel bipolar plate will significantly reduce, and the corrosion current increases. The effect of F- ion concentration on the corrosion resistance of CrxN film / 316L stainless steel bipolar plate is a complex process. When the F- ion concentration is small, it might have some inhibitory effects to the corrosion of CrxN film / 316L stainless steel bipolar plate in acidic media, But when F- ion concentration exceeds a certain amount, they will significantly speed up the corrosion of CrxN film / 316L stainless steel bipolar plate in acid medium.
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