钛双极板表面原位生成TiN涂层的性能研究

Property of TiN Coating on Surface of Ti Bipolar Plate

目的降低钛合金表面的接触电阻,提高其抗腐蚀性能。方法 TA2纯钛表面进行活化后,原位反应生成TiN涂层。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)分析表面形貌和成分,使用直流表面电阻和界面接触电阻(ICR)来评价涂层的导电性,在模拟质子交换膜燃料电池(PEMFC)环境中测试其抗腐蚀性能。结果经过TiN处理后的TA2纯钛双极板表面致密,其生长方式为沿(111)晶面择优生长。在750℃反应2 h获得的试样的直流表面电阻和ICR电阻最低,抗腐蚀性能最佳。压力为120N/cm^2时,电阻率稳定在6.7 m?/cm^2。在模拟PEMFC环境中的表面腐蚀电流为0.816μA/cm^2,经过恒电位扫描后的SEM显示,其表面完整,H2气氛中涂层界面完整,空气气氛中出现较多点蚀。结论在TA2纯钛表面原位反应生成TiN涂层有助于提高基体表面的抗腐蚀性和导电性。

The work aims to reduce contact resistance and improve corrosion resistance of Ti alloy surfaces. After activation on the surface of TA2, TiO2 developed into TiN coating in in-situ reactions. Surface morphology and composition of the coating were analyzed with X-ray diffractometer （XRD）, scanning electron microscope （SEM） and energy spectrum analysis （EDS）; conductivity of the coating was evaluated based upon interfacial contact resistance （ICR） and DC surface resistance; corrosion resistance of the coating was tested simulated proton exchange membrane fuel cell （PEMFC） environment. The TA2 bipolar plate treated with TiN had dense surface and grew preferentially along （111） crystal face. Samples receiving 2 h in-situ reaction at 750 ℃ exhibited the minimum ICR and DC surface resistance as well as the optimal corrosion resistance. Provided with pressure of 120 N/cm2, the resistivity stabilized at 6.7 mΩ/cm2. The surface corrosion current was 0.816 μA/cm2 in the simulated PEMFC environment. SEM showed that the surface was complete, the coating interfaces were complete in H2 atmosphere, and much pitting corrosion occurred in air atmosphere after scanning of constant electric potential. TiN coating produced on the surface of TA2 in in-situ reaction is conductive to improving its corrosion resistance and conductivity.