平板电极微细电解加工金属表面微流道技术研究

The machining process of the micro-scaled flow channels is the crucial link of the fabrication of the metallic bipolar plates, which are the main components of the proton exchange membrane fuel cell(PEMFC). The micro-electrochemical machinging has unique advantages in generating the micro-scaled flow channels in the metallic materials. However, the machining product is difficult to remove, and the insulation layer is easily broken by the flown electrolyte with the high speed during the electrochemical pattern transfer. To solve these problems, the electrochemical pattern transfer with the plate electrode is developed in this project. It is also carried out the research about the micro-scaled flow channels machining in the metallic bipolar plate with the new technology.During the machining processing, the plate electrode with good cementing property between the insulation layer and the metallic substrate can improve the flow field stability in the interelectrode gap and the ability of the electrochemical micro-machining (EMM). The basic theories in the research include the processing principle of the electrochemical pattern transfer with the plate electrode, the forming process of the flow channels and the transportation process of the micro product in the microscale interelectrode gap. The key technologies in the research include the preparation of the plate electrode, the development of the experimental platform for the electrochemical pattern transfer with the plate electrode and the experimental investigation of the flow channels machining with the innovative electrochemical pattern transfer.With these crucial problems settled, the problem about the manufacture of the micro-scaled flow channels will be solved by the electrochemical pattern transfer with the plate electrode.

金属表面微流道加工是制作质子交换膜燃料电池金属双极板的关键环节。微细电解加工工艺对于加工金属表面微流道具有独特的优势。为克服目前电解加工微流道存在的加工产物排放困难和金属基底与绝缘层结合力小等问题，本项目提出了平板电极电解转印工艺，并采用该工艺进行金属双极板表面微流道加工技术的研究。该技术中采用的平板电极绝缘层与金属基底有较强的结合力，同时在电解加工过程中，可以有效地改善加工间隙内流场的稳定性，提高电解的微细加工能力。研究内容包括平板电极电解转印微流道加工原理、流道成形过程以及微尺度间隙流场中微细电蚀产物的运输过程等基础理论问题，突破电解转印平板工具阴极制备、平板电极电解转印加工试验平台研制、平板电极电解转印加工微流道试验研究等关键技术，解决燃料电池金属双极板表面微流道的制造难题。

金属表面微流道加工技术是制作质子交换膜燃料电池金属双极板的关键环节。双极板表面微流道电解转印工艺对于加工金属表面微流道具有独特优势。为了加速电解产物的排出和提高工具阴极模板的使用效率，本项目提出采用平板电极电解转印加工金属双极板表面微流道，并采用该工艺进行金属双极板表面微流道加工技术的研究。主要研究内容包括平板电极电解转印微流道加工原理、应用电场理论建立加工间隙电场的数学模型、工件阳极表面电场分布情况、数值分析计算模拟流道成形过程以及微尺度流场中微细电蚀产物的运输过程等基础问题，分别采用光刻技术、激光直写技术和3D打印技术解决了工具阴极制作难题，突破了平板电极电解转印加工试验平台研制、平板电极电解转印加工微流道试验研究等关键技术。通过改进工具阴极模板制作工艺，优化电解液流场方式和电解试验加工参数，实现了在金属双极板表面一次性加工多条微细蛇形流道，流道宽度可控制在数百微米，深度可控制在数十微米，和传统模板加工金属表面微流道相比，该工艺中工具阴极模板可反复使用，大幅降低了加工成本，提高了加工效率，易于实现批量化生产，为电解转印在工程中应用提供了重要支撑。该项目是在传统掩模电解加工技术和电解转印技术的基础上，经过前期的酝酿、探索和积累所形成的对电解转印工艺的改良，并成功制造燃料电池双极板表面微流道，实现了由基础研究转向工程运用，为质子交换膜燃料电池商业化提供重要保障。