图2.46为各个腐蚀时间段的试样垂直于焊缝的EDS线扫描结果,试样焊缝及其附近表面的主要元素有O、Al、Si、Ag、Cu、Cl、K、Ca。由图2.46(b)得,试样在腐蚀24小时后钎焊接头表面的元素主要为O、Al、Si、Ag、Cu这几种元素,图2.46(d)为腐蚀96h后的线扫图,与图2.46(b)对比后发现有新增Cl、Ca、Fe、K元素出现,其原因是腐蚀96小时后300Al中含有的少量Fe元素出现在试样表面与氧发生反应产生氧化产物附着在试样表面,Cl、Ca、K元素则是所使用的工业NaCl中所含有的元素,积累后出现在试样表面。在腐蚀196小时后试样表面很难找到焊缝的位置,表面有大量的腐蚀物覆盖,通过线扫图片分析可知有部份Al元素以及从铝侧进入到铜侧。图2.46(h)为腐蚀240小时后的试样表面,尽量找到一处焊缝清晰处进行线扫,焊缝铝侧的腐蚀产物已经开始相对致密的排列,不再杂乱无章的排列。
Fig. 2.46 shows the EDS line scanning results of samples perpendicular to the weld in each corrosion period. The main elements in the weld and its adjacent surface are O, Al, Si, Ag, Cu, Cl, K and Ca.It can be seen from Fig. 2.46 (b) that the elements on the brazed joint surface of the sample after 24 hours of corrosion are mainly O, Al, Si, Ag and Cu. Fig. 2.46 (d) shows the line scan after 96 hours of corrosion. Compared with Fig. 2.46 (b), additional Cl, Ca, Fe and K elements appear.The reason is that after 96 hours of corrosion, a small amount of Fe contained in 300Al appeared on the surface of the sample and reacted with oxygen to produce oxidation products attached to the sample surface. Cl, Ca and K were elements contained in the industrial NaCl used and appeared on the sample surface after accumulation.After 196 hours of corrosion, it is difficult to find the weld position on the surface of the sample. The surface is covered by a large number of corrosive materials. Through the analysis of the line scan picture, it can be seen that there is a part of Al element and it enters from the aluminum side to the copper side.Figure 2.46 (h) shows the sample surface after 240 hours of corrosion. Try to find a clear weld for line scanning. Corrosion products on the aluminum side of the weld have begun to arrange in a relatively compact way instead of in a random way.