焊后钎剂残渣腐蚀行为分析

采用扫描电子显微镜、电化学工作站等手段对同一型号不同药芯钎料钎剂残渣的腐蚀行为进行了系统研究分析。研究结果表明：钎料和基体在钎剂溶液中均发生了腐蚀，基体的腐蚀速率整体明显高于钎料的腐蚀速率；腐蚀速率随着时间的延长不断降低，但腐蚀并未停止。钎料组织越细，晶界越多，晶界处非规则排列的原子将发生较多腐蚀反应，耐腐蚀性下降。高温加速试验后Fe基体和镀锌层间出现微观裂纹，钎剂中强腐蚀性物质已渗透到界面层；在镀锌层区域，锌元素大量被氧化，形成了ZnO；在残留钎剂层区域，Fe,Zn元素含量较高，耐蚀性较差的Fe元素部分已扩散到残留钎剂层区域，形成铁的氧化物，同时又与NaCl等发生反应，形成FeCl3等物质。 创新点： 探明了钎剂残渣的腐蚀行为，明确其对钎焊接头可靠性的影响程度。

Analysis of flux residue corrosion behavior after brazing

The corrosion behavior of flux residue was studied systematically by means of scanning electron microscope and electrochemical workstation. The results showed that both the brazing filler metal and the matrix corroded in the aqueous solution of flux, and the corrosion rate of the matrix was obviously higher than the brazing filler metal. The corrosion rate decreased with time, but not stopping. The finer the solder structure was, the more corrosion reactions will occured in the atoms with irregular arrangement at grain boundary, and the corrosion resistance would decrease. There were microscopic cracks between the zinc layer and Fe matrix of bundy tube, and strong corrosive substances in the brazing agent had penetrated into the interface layer. In the zinc-coated region, a large amount of zinc element was oxidized to form ZnO. In the region of residual brazing agent layer, Fe and Zn elements with high content and poor corrosion resistance had diffused into the region of residual brazing agent layer to form iron oxides, and some of them react with NaCl to form FeCl3 and other substances. Highlights: The corrosion behavior of the flux residue was investigated and its influence on the reliability of the brazing joint was determined.