模拟PEMFC环境下纳米晶ZrC涂层钛合金双极板的性能研究  

Properties of ZrC Nanocrystalline Coating on Ti Alloy Bipolar Plates in Simulated PEMFC Environments

作　　者：钱阳[1] 徐江[1] 

机构地区：[1]南京航空航天大学,江苏南京210016

出　　处：《稀有金属材料与工程》2017年第4期1033-1042,共10页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51374130);航空科学基金(2013ZE52058)

摘　　要：采用双阴极等离子溅射沉积技术,在Ti-6A1-4V合金表面制备了厚度为10μm、平均晶粒尺寸为12 nm的ZrC纳米晶涂层。研究了改性前后钛合金双极板在质子交换膜燃料电池环境中的耐腐蚀性能、导电性能以及憎水性能。结果表明:在模拟PEMFC阴/阳极环境中,纳米晶ZrC涂层的腐蚀电位明显高于Ti-6A1-4V合金,而腐蚀电流密度较Ti-6A1-4V合金降低约4个数量级。在+0.6 V阴极工作电极电位下,纳米晶ZrC涂层具有更快的成膜速率以及更高的钝化膜稳定性;而在–0.1 V阳极工作电极电位下,ZrC纳米晶涂层则呈现出阴极保护特征。To improve the corrosion resistance and interfacial contact resistance （ICR） in polymer electrolyte membrane fuel cells （PEMFC） environment, ZrC nanocrystalline coating was fabricated on Ti-6A1-4V substrate by a double cathode glow discharge technique. The microstructure of the as-prepared ZrC coating was characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM） and transmission electron microscopy （TEM）. Results show that the microstructure of the ZrC coating is continuous and compact, consisting of deposited layer and diffusion layer. The 10 p.m thick deposited layer is composed of equiaxed grains with an average grain size of-12 nm, whereas the 4 μm thick diffusion layer with the gradient distribution of alloying elements offers a smooth transition of mechanical properties, which is suitable to improve the adhesion strength of the ZrC coating on the Ti-6Al-4V substrate. The electrochemical behavior of ZrC nanocrystalline coating was evaluated in the simulated PEMFC anodic and cathodic environments. The Ecorr of the as-deposited ZrC nanocrystalline coating is obviously higher than that of Ti-6Al-4V alloy in a simulated PEMFC environment. At applied cathode （＋0.6 V） potential for PEMFC, ZrC nanocrystalline coating is in passive region, and the passive current density is four orders of magnitude lower than that of Ti-6Al-4V alloy. At applied anode （-0.1 V） potential, ZrC nanocrystalline coating exhibits the characteristic of cathodic protection. The results of EIS show that the values of capacitance semicircle, phase angle maximum as well as the frequency range with the phase angle near -80 o are larger than those of Ti-6Al-4V alloy in the simulated PEMFC environment. Moreover, ZrC nanocrystalline coating can effectively improve conductivity and hydrophobic nature of Ti-6Al-4V alloy bipolar plate.

关 键 词：质子交换膜燃料电池 双极板 纳米晶ZrC涂层 TI-6A1-4V合金 耐蚀性 接触电阻 

分 类 号：TG174.4[金属学及工艺—金属表面处理]