燃料电池双极板结构激光增材制造及表面精整加工  

Optimization of polishing process for bipolar plates in fuel cells manufactured via laser additive manufacturing

作　　者：张万里 林开杰 陕俊豪 许勇 黄广靖 孙婧佳 顾冬冬[1,2] ZHANG Wanli;LIN Kaijie;SHAN Junhao;XU Yong;HUANG Guangjing;SUN Jingjia;GU Dongdong(School of Materials Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 210000,Jiangsu,China;Jiangsu Provincial Research Center for Laser Additive Manufacturing of High-Performance Components,Nanjing 210016,Jiangsu,China)

机构地区：[1]南京航空航天大学材料科学与技术学院,江苏南京210000 [2]江苏省高性能构件激光增材制造工程研究中心,江苏南京210016

出　　处：《钢铁》2024年第6期60-71,共12页Iron and Steel

基　　金：国家重点研发计划资助项目(2021YFB1715400);国防基础科研计划资助项目(JCKY2020605C007);江苏省重点研发计划资助项目(BE2022069,BE2022069-1)。

摘　　要：质子交换膜燃料电池双极板异形截面微流道制造成形存在挑战,且表面粗糙度对其性能与寿命造成重要影响。激光粉末床熔融(laser powder bed fusion,LPBF)技术得益于成形自由度高、可实现复杂结构成形等特点,在解决该复杂微流道成形问题方面具有显著优势,且磨粒流加工可实现复杂流道的高效精抛光。采用LPBF技术成形了316L不锈钢质子交换膜燃料电池双极板异形截面微流道结构,获得了优化的激光工艺(激光功率为150 W,扫描速度为800 mm/s,扫描间距为50μm),该工艺下成形试样致密度为99.5%。自主研发设计了磨粒流抛光设备及夹具,对优化工艺下LPBF成形的异形截面微流道进行了抛光工艺优化,基于光镜、激光共聚焦和扫描电子显微镜等试验手段,研究了不同抛光压力对LPBF成形质子交换膜燃料电池双极板异形截面微流道成形精度、表面粗糙度及显微组织的影响规律,获得了最佳磨粒流抛光工艺(抛光压力为9 MPa、抛光时间为90 min、磨粒粒径为0.037 5 mm)。结果表明,随着抛光压力增大,微流道内壁质量得到了有效提升且沿微流道长度方向的抛光不均现象明显改善,抛光压力为9~11 MPa时,成形构件表面粗糙度低至2.43~3.57μm,改善量可达77.9%~85.7%。流道结构顶部硬度最小,变化量最大,与悬垂位置的致密度及显微组织有关。其中抛光压力为9 MPa时,中间及出口处的设计总偏差量最小,分别为61μm和82μm。揭示了磨粒流抛光LPBF成形燃料电池双极板异形截面微流道的机制,以期为LPBF成形复杂结构的表面精整工作提供参考。Manufacturing complex-shaped microchannels on proton exchange membrane fuel cell(PEMFC)bipolar plates poses challenges,and surface roughness significantly affects their performance and lifespan.Laser powder bed fusion(LPBF),with its high degree of formability and capability to produce complex structures,offers significant advantages in forming these intricate microchannels.Moreover,abrasive flow machining enables efficient polishing of complex channels.LPBF was employed to fabricate 316L stainless steel PEMFC bipolar plates with complexshaped microchannel structures.Optimized laser parameters(laser power of 150 W,scanning speed of 800 mm/s,and scanning spacing of 50μm)resulted in a sample density of 99.5%.A custom abrasive flow polishing device and fixtures were developed to optimize the polishing process for LPBF-fabricated microchannels.Through experimental techniques including optical microscopy,laser confocal microscopy,and scanning electron microscopy,the effects of different polishing pressures on the dimensional accuracy,surface roughness,and microstructure of LPBFfabricated PEMFC bipolar plates with complex-shaped microchannels were investigated.Optimal abrasive flow polishing parameters(polishing pressure of 9 MPa,polishing time of 90 min,and abrasive particle size of 0.0375 mm)were determined.Increasing the polishing pressure effectively enhanced the quality of the microchannel inner walls and significantly improved the unevenness along the length of the microchannels.At polishing pressures of 9-11 MPa,surface roughness of the fabricated components reduced to 2.43-3.57μm,with an improvement of up to 77.9%-85.7%.The top of the channel structure exhibited the lowest hardness and the most significant variation,correlating with the density and microstructure at the hanging position.Specifically,at a polishing pressure of 9 MPa,the total design deviation at the midpoint and exit of the microchannels was minimized,measuring 61μm and 82μm,respectively.The mechanism of abrasive flow polishing for LPBF-forme

关 键 词：激光增材制造 磨粒流 燃料电池 微流道 表面精整 抛光压力 

分 类 号：TM911.4[电气工程—电力电子与电力传动]