PEMFC不锈钢双极板表面改性用Cr-C薄膜的成分设计与制备

Composition Design and Preparation of Surface Modified Cr-C Film of Stainless Steel Bipolar Plate for PEMFC

目的根据质子交换膜燃料电池(Proton Exchange Membrane Fuel Cell,PEMFC)不锈钢双极板的表面镀膜改性要求,探索改性薄膜成分对性能的影响规律,并提供一种行之有效的薄膜成分设计方法。方法首先应用团簇加连接原子结构模型,结合电子轨道饱和原则,理论上设计出Cr-C二元材料体系的最佳团簇式和最佳成分,再利用电弧离子镀技术在316L不锈钢双极板上制备出一系列不同成分的CrxC1-x薄膜,对薄膜的成分、结构及性能进行表征和分析。结果设计所得Cr-C材料体系的最佳团簇式为[Cr-C4]CrC3,对应的最佳原子比成分为Cr0.22C0.78。所制备的CrxC1-x薄膜的成分系数x在0.05~0.23之间变化,薄膜的导电性和耐蚀性能随着成分x的增加,呈明显增加趋势。其中Cr0.23C0.77薄膜的综合性能最好:在1.2MPa压紧力下,接触电阻为2.8 mΩ·cm^2;在模拟腐蚀环境下,腐蚀电流密度仅为9.1×10-2μA/cm^2。该性能已优于美国能源部DOE的标准指标要求。结论Cr-C改性薄膜的成分对导电性能和耐蚀性能有着重要的影响。由于实验制备的性能最佳的薄膜成分Cr0.23C0.77与基于团簇加连接原子模型设计薄膜的最佳成分Cr0.22C0.78基本相同,从而证实了依据此模型进行双极板改性薄膜成分设计是行之有效的。

The work aims to explore the effect of modified film components on performance and provide an effective method of film composition design according to the surface modification requirements for the stainless steel bipolar plate of the proton exchange membrane fuel cell(PEFMC).Firstly,based on the cluster-plus-glue-atom model and the electron orbital saturation principle,the optimal cluster type and the optimal composition of Cr-C binary material system were designed theoretically.A series of CrxC1-x films with different compositions were prepared on the 316 L stainless steel bipolar plate by arc ion plating technology.The composition,structure and performance of the film were characterized and analyzed.The optimal cluster formula of the obtained Cr-C material system was[Cr-C4]CrC3,and the corresponding optimal atomic ratio composition formula was Cr0.22C0.78.The composition coefficient x of the prepared CrxC1-x film was between 0.05 and 0.23.The electrical conductivity and corrosion resistance of the film increased significantly with the increase of the component x.Among these films,Cr0.23C0.77 film had the best comprehensive performance:the interface contact resistance was 2.8 mΩ·cm^2 under the compaction force of 1.2 MPa and the corrosion current density was only 9.1×10-2μA/cm^2 in the simulated corrosion environment.The performance was better than that required by technical standards of DOE.The composition of Cr-C modified film has an important influence on the conductivity and corrosion resistance.Since the Cr0.23C0.77 thin film with the best performance has basically the same composition as the ideal optimal composition formula[Cr-C4]CrC3(Cr0.22C0.78)obtained based on the cluster-plus-glue-atom model,it is confirmed that the composition design of the modified film of the bipolar plate based on this model is effective.