6063铝合金镀银前处理工艺

Pretreatment of 6063 aluminum alloy for silver plating

对镀银层结合力不良的6063铝合金进行了表面微观形貌观察和元素分析,结果发现材料表面镁含量超标。镁会与含氟酸洗液中的氟离子在基材表面生成不溶于酸的MgF2,影响后续电镀质量,造成镀银层结合力不良。对酸洗液配方进行了改进,确定了酸洗的工艺条件为:硝酸300mL/L,磷酸100mL/L,除垢剂300mL/L,温度10～40°C,时间1min。以此工艺进行酸洗,镁含量超标的铝合金零件镀银后的合格率可提高至70%,正常零件的合格率可达95%以上。

The results of SEM observation and elemental analysis showed that the poor adhesion of electroplated silver coating on 6063 A1 alloy is mainly due to the excess of surface magnesium content of the alloy. Magnesium reacts with fluorine ion in fluorine-containing pickling solution, producing insoluble MgF2 on the surface of substrate, which affects the quality of subsequent plating process and results in a poor adhesion of silver coating. The pickling process was improved and the optimal bath composition and operation conditions were presented as follows： HNO3 300 mL/L, H3PO4 100 mL/L, descaling agent 300 mL/L, temperature 10-40 ~C, and time 1 min. The percentage of eligible silver-plated products is raised to 70% for the A1 alloy parts with excessive .magnesium content and more than 95% for the parts with normal magnesium content.