CAJ | 학술논문

为改善金属双极板在质子交换膜燃料电池(PEMFC)环境中的耐腐蚀性能及降低其界面接触电阻，采用双阴极等离子溅射沉积技术，在Ti-6A1-4V合金表面制备了纳米晶Zr涂层.利用扫描电子显微镜(SEM)， X射线衍射(XRD)和透射电子显微镜(TEM)等微观分析手段对该涂层的组织结构进行了表征.结果表明：所制备的涂层具有沉积层和扩散层的双层结构，其微观组织连续、致密.在分别通入氢气/空气、70° C的0.5 mol?L-1 H2SO4+2 mg?L-1 HF的溶液中，对比研究了纳米晶Zr涂层与Ti-6A1-4V合金在模拟电池的阳极/阴极工作环境中的电化学腐蚀性能.动电位极化测试结果表明：在模拟电池的阳极/阴极工作环境中，纳米晶Zr涂层的腐蚀电位均明显高于Ti-6A1-4V合金；在阴极工作电极电位为+0.6 V下，纳米晶Zr涂层与Ti-6A1-4V合金均位于钝化区内， Zr涂层的钝化电流密度较Ti-6A1-4V合金降低约4个数量级；而在阳极工作电极电位为-0.1 V下，纳米晶Zr涂层呈现出阴极保护特征.电化学阻抗谱测试结果表明，在0.5 mol?L-1 H2SO4+2 mg?L-1 HF的溶液中，纳米晶Zr涂层的容抗弧半径和相位角的最大值及其频率宽度均明显大于Ti-6A1-4V合金.此外，纳米晶Zr涂层同时改善了Ti-6A1-4V合金的导电性与憎水性能.
위개선금속쌍겁판재질자교환막연료전지(PEMFC)배경중적내부식성능급강저기계면접촉전조，채용쌍음겁등리자천사침적기술，재Ti-6A1-4V합금표면제비료납미정Zr도층.이용소묘전자현미경(SEM)， X사선연사(XRD)화투사전자현미경(TEM)등미관분석수단대해도층적조직결구진행료표정.결과표명：소제비적도층구유침적층화확산층적쌍층결구，기미관조직련속、치밀.재분별통입경기/공기、70° C적0.5 mol?L-1 H2SO4+2 mg?L-1 HF적용액중，대비연구료납미정Zr도층여Ti-6A1-4V합금재모의전지적양겁/음겁공작배경중적전화학부식성능.동전위겁화측시결과표명：재모의전지적양겁/음겁공작배경중，납미정Zr도층적부식전위균명현고우Ti-6A1-4V합금；재음겁공작전겁전위위+0.6 V하，납미정Zr도층여Ti-6A1-4V합금균위우둔화구내， Zr도층적둔화전류밀도교Ti-6A1-4V합금강저약4개수량급；이재양겁공작전겁전위위-0.1 V하，납미정Zr도층정현출음겁보호특정.전화학조항보측시결과표명，재0.5 mol?L-1 H2SO4+2 mg?L-1 HF적용액중，납미정Zr도층적용항호반경화상위각적최대치급기빈솔관도균명현대우Ti-6A1-4V합금.차외，납미정Zr도층동시개선료Ti-6A1-4V합금적도전성여증수성능.
A zirconium nanocrystal ine coating has been fabricated on a Ti-6A1-4V al oy bipolar plates using a double cathode glow discharge technique to improve the corrosion resistance and reduce the interfacial contact resistance in polymer electrolyte membrane fuel cel s (PEMFCs). The microstructure of Zr coating was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The microstructure of the Zr coating was found to be continuous and compact;consisting of deposited and diffusion layers. The deposited layer was 30μm thick and composed of equiaxed grains with an average grain size of around 15 nm, whereas the diffusion layer was 10μm thick with a gradient distribution of al oying elements, which offered a smooth transition of mechanical properties that were suitable for improving the adhesion strength of the Zr coating on the Ti-6A1-4V substrate. The electrochemical behavior of the Zr coating was evaluated in 0.5 mol?L-1 H2SO4 solution containing 2 mg?L-1 of HF solution at 70 °C to simulate the environment found in a PEMFC. The solution was purged with H2 (simulated PEMFC anodic environment) or air (simulated PEMFC cathodic environment). The Ecorr of the deposited Zr nanocrystal ine coating was much higher than that of the Ti-6A1-4V al oy in the simulated PEMFC environment. At the applied cathode (+0.6 V) potentials for PEMFCs, both the Zr nanocrystal ine coating and Ti-6A1-4V al oy were in the passive region, but the passive current density of the as-deposited Zr nanocrystal ine coating was four orders of magnitude lower than that of the Ti-6A1-4V al oy. At the applied anode (-0.1 V), the Zr nanocrystal ine coating exhibited characteristic cathodic protection behavior. The results of electrochemical impedance spectroscopy (EIS) showed that the values of the capacitance semicircle, phase angle maximum and frequency range were larger than those of the Ti-6A1-4V al oy in the simulated PEMFC environment when the phase angle was near-80°. Moreover, the Zr nanocrystal ine coating effectively improved the conductivity and hydrophobicity of the Ti-6A1-4V al oy bipolar plate.