过电位抛光增材制造双极板流道结构及性能研究

Structure and Performance of Bipolar Plate Flow Channel by Overpotential Polishing Additive Manufacturing

目的 研究过电位抛光对不锈钢异形截面微流道内壁成形性及双极板性能的影响。方法 采用电化学实验、扫描电子显微镜(SEM)、粗糙度测试分别对激光粉末床熔融技术成形异形截面微流道进行测试分析,研究抛光时间对微流道内壁表面形貌、典型缺陷、表面粗糙度及双极板耐腐蚀性的影响。结果 在抛光前10 min,微流道内壁的质量得到有效提升,随着抛光时间的延长,其表面粗糙度达到稳定值,同时典型缺陷也由黏粉、半熔金属颗粒等局部缺陷逐渐变化到球化、挂渣、阶梯效应等大范围缺陷,直至出现点蚀现象。抛光时间在5~15 min内,LPBF成形316L不锈钢表面质量提升,随着抛光时间的增加,其耐腐蚀性下降。结论 采用过电位抛光工艺并选择适当的过电位抛光时间,能有效提升微流道内壁成形质量及双极板耐腐蚀性能。

The work aims to study the effect of overpotential polishing on the formability of the inner wall of stainless steel irregular cross-section microchannels and the performance of bipolar plates.The electrochemical test,scanning electron microscopy(SEM),and roughness test were adopted to analyze the laser power bed fusion(LPBF) shaped microchannels.The effects of polishing time on the surface morphology,typical defects,surface roughness,and corrosion resistance of microchannels were studied.In the first 10 minutes of polishing,the quality of the inner wall of microchannel was effectively improved.With the extension of polishing time,the surface roughness reached a stable value,and the typical defects gradually changed from local defects such as sticky powder and semi molten metal particles to large-scale defects such as spheroidization,slag hanging,and step effect,until pitting.Within 5~15 minutes of polishing,the surface quality of LPBF formed 316L stainless steel was improved.With the extension of polishing time,its corrosion resistance decreased.Adopting an overpotential polishing process and selecting an appropriate overpotential polishing time can effectively improve the forming quality of the inner wall of the microchannel and the corrosion resistance of bipolar plate.