铁路继电器触点表面形貌及失效机理分析  

Analysis of Surface Morphology and Failure Mechanism of Railway Relay Contacts

作　　者：李文华[1] 李爽[1] 卢文将 赵月山 LI Wen-hua;LI Shuang;LU Wen-jiang;ZHAO Yue-shan(National Key Laboratory Co-Founded by Tianjin and Ministry of Education for Reliability and Intelligence of Electrical Equipment,Hebei University of Technology,Tianjin 300130,China)

机构地区：[1]河北工业大学,省部共建电工装备可靠性与智能化国家重点实验室,天津300130

出　　处：《表面技术》2018年第8期236-243,共8页Surface Technology

摘　　要：目的深入研究铁路继电器触点的失效机理。方法在直流条件下进行铁路继电器电寿命试验,自动识别静触点表面与动触点的接触区域。利用三维形貌扫描仪和扫描电镜扫描触点,选定平面基准面,计算触点表面粗糙度参数,分析触点表面形貌变化。对触点烧蚀后的表面进行元素分析,研究触点表面的微观组织结构和失效机理。结果 Sa/Sq的值小于0.8表示随机性较强的表面,Sa/Sq(静)=0.246<Sa/Sq(动)=0.291,即继电器触点在额定运行后,表面凹凸形貌均具有很强的随机性,静触点表面的随机性明显强于动触点。分析继电器动、静触点起伏变化(Sp+Sv),静触点为109.786,远大于动触点26.08,表明静触点的起伏变化明显,幅度较大,动触点幅度变化较小,相对平坦。继电器表面基本以Ag和Cd元素为主,Cd含量变化平稳,在明显裂缝处含量极低。相对于动触点,静触点表面凹坑和龟裂状裂纹清晰可见,腐蚀严重。裂缝凹坑区域和凹坑边缘区域Ag和Cd的原子百分比约为2∶1,磨损颗粒区域Ag和Cd的原子百分比约为0.5∶1。相对平坦区域腐蚀程度很浅,Ag和Cd的原子百分比约为5∶1。触点阴极,即静触点表面,存在反应Cd+2OH^-→Cd(OH)_2+2e,部分Ag被磨损,附着在动触点凸起表面。另一部分Ag进行反应Ag++Cl-→Ag Cl,绝大多数Ag进行了Ag+O→Ag_2O反应。结论归纳出了表面形貌和失效之间的联系,动触点表面有微小颗粒沉积,表面高度变化区域性明显。静触点表面凹凸裂痕分界清晰,表面高度变化呈现横向规律性。触点在裂缝凹坑和凹坑边缘区域元素腐蚀情况相当,磨损颗粒区域存在一部分材料从阴极转移到阳极,相对平坦区域存在一部分材料从阳极转移到阴极。The work aims to study the failure mechanism of railway relay contacts.The electric relay electric life test was carried out under the direct current condition to automatically recognize the contact area between the static contact surface and the moving contact.3D topography scanner and SEM were used to scan the contacts,the plane reference surface was selected,the contact surface roughness parameters were calculated,and the surface topography changes of the contact surfaces were analyzed.Elemental analysis was performed on the ablated surface of the contact to investigate the microstructure and failure mechanism of the contact surface.The Sa/Sq value less than 0.8 indicated a random surface.For Sa/Sq(static)=0.246<Sa/Sq(moving)=0.291,after the rated operation of relay contact,the surface roughness was of strong randomness and the randomness of the static contact surface was significantly stronger than that of the moving contact.For the analysis of the relay dynamic and static contact fluctuations(Sp+Sv),the static contact was 109.786,much larger than the moving contact 26.08,which indicated that the static contact fluctuations changed significantly with large amplitude,while the dynamic contact amplitude change was relatively small and flat.The surface of the relay was mainly composed of Ag and Cd,but the Cd content changed smoothly and was very small at obvious cracks.Compared with those on dynamic contact surface,the pits and cracks on the surface of the stationary contact were clearly visible and corrosive.The atomic percentage of Ag and Cd in the pit region and pit edge region was about 2∶1,while the atomic percentage of Ag and Cd in the wear particle region was about 0.5∶1.The corrosion degree was relatively shallow in the flat region,so the atomic percentage of Ag and Cd was about 5∶1.The contact cathode,the static contact surface,had a reaction:Cd+2OH^-→Cd(OH)2+2e.Part of the Ag was worn away and adhered to the surface of the movable contact bump;another part of the Ag reacted:Ag^++Cl^-→AgCl;and

关 键 词：铁路继电器 表面形貌 表面元素 粗糙度参数 失效机理分析 材料转移 

分 类 号：TG172[金属学及工艺—金属表面处理] U224.4[金属学及工艺—金属学]