绝缘子引线腐蚀断裂研究

Study on corrosion and fracture of insulator lead

[目的]绝缘子作为微波组件内、外部的连接器件,其引线与玻璃封接处容易断裂。[方法]采用金相显微镜、扫描电镜、能谱仪等手段对上述断裂的原因进行分析。[结果]通过机理探讨与现场观察相结合,确定症结在于应力腐蚀开裂。绝缘子引线断裂分为3个阶段:点蚀过程及裂纹萌生,裂纹扩展,以及纯力学快速断裂。[结论]采用化学抛光与机械研磨相结合、镍金交叉镀覆的新工艺可以消除绝缘子引线封接处镀层应力敏感性和应力条件,令镀层的结合力、耐盐雾性能及焊接性能均达到工艺要求。

[Introduction]Insulators are widely used as a device connecting the inside and outside parts of microwave component.The fracture of the connecting part of its lead and glass base often occurred.[Method]The causes of this problem were analyzed by metallography,scanning electron microscopy,and energy-dispersive spectroscopy.[Result]Stress corrosion cracking was determined to be the key reason through the combination of mechanism analysis and on-site observation.The fracture of insulator lead can be divided into three stages:first,pitting and crack initiation;second,crack propagation;and third,pure mechanical rapid fracture.[Conclusion]The application of chemical polishing and mechanical grinding as pretreatments and electroplating with nickel and gold alternately can eliminate the stress sensitivity of coating and the conditions for initiation of stress at the lead seal,making the coatings meet the technical requirements of adhesion,salt spray resistance,and weldability.