硅烷流量对钛合金双极板表面改性碳膜性能的影响

目的通过对钛合金基底进行表面改性,提高其作为质子交换膜燃料电池(PEMFC)金属双极板的耐蚀导电性能。方法通过等离子体增强化学气相沉积法(PECVD),调控不同的SiH4流量(0~10 mL/min),在钛基底表面制备了含硅非晶碳膜。利用电化学工作站、界面接触电阻测量仪、水接触角测量仪、纳米压痕仪,分别测试了薄膜的耐蚀性、导电性、疏水性和力学性能。通过拉曼光谱分析了腐蚀前后薄膜内部杂化比变化,并结合扫描电子显微镜和高分辨透射电子显微镜研究了薄膜厚度、腐蚀形貌和内部结构。结果SiH4流量为8 mL/min时,制备的含硅非晶碳膜具有最佳耐蚀性和导电性,该含硅非晶碳膜水接触角为102.91°,硬度为9.28 GPa,弹性模量为60.34 GPa,厚度为2.822μm。其动电位腐蚀电流密度为0.017μA/cm^2,相比钛基底提升3个数量级(80.51μA/cm^2),在1.4 MPa压力下,其界面接触电阻为47.06 mΩ·cm^2。结论硅的引入诱导非晶碳膜生成类石墨烯结构,提高了非晶碳膜的导电性能和耐蚀性能,提升了薄膜的力学性能及疏水性。用含硅非晶碳膜对钛双极板进行表面改性,有望显著提高极板的燃料电池性能。

Effect of Silane Flow Rate on the Properties of Modified Carbon Film on the Surface of Titanium Alloy Bipolar Plate

Silicon-containing amorphous carbon films,via adjusting silane flow rates(0~10 mL/min),were deposited on the surface of the titanium alloy by plasma enhanced chemical vapor deposition to improve the performance of the titanium alloy bipolar plate.The corrosion resistance,conductivity,hydrophobicity,and mechanical properties of the silicon-containing amorphous carbon film were tested by electrochemical workstation,interface contact resistance measuring instrument,water contact angle measuring instrument and nano-indentation instrument.The internal hybridization ratio of the films before and after corrosion were analyzed by Raman spectroscopy.The thickness,corrosion morphology and internal structure of the films were explored by scanning electron microscope and high-resolution transmission electron microscope.The silicon-containing amorphous carbon film,which prepared under the silane flow rate of 8 mL/min(a-C:Si(8)),with hardness and elastic modulus of about 9.28 GPa and 60.34 GPa,have the best corrosion resistance and conductivity.Its dynamic potential corrosion current density was 0.017μA/cm^2,lower by 3 magnitudes than that of titanium alloy substrate(80.51μA/cm^2).For the a-C:Si(8)film,Its interface contact resistance was 47.06 mΩ·cm^2(1.4 MPa),and its water contact angle was 102.91°,and its thickness was 2.822μm,respectively.After corrosion the surface of this film was not significantly damaged compared to other films.Through highresolution transmission electron microscopy,it was found that the introduction of silicon could induce the amorphous carbon film to generate graphene-like sheets,which could improve the electrical conductivity and corrosion resistance of the amorphous carbon film,and also improve the mechanical properties and hydrophobicity of the film.Our results suggest that the surface modification of the titanium alloy bipolar plate by the silicon-containing amorphous carbon film could effectively improve the fuel cell performance of the bipolar plate.