LY12铝合金氧化膜与钎剂的反应机制

采用CsF-AlF3中温无腐蚀钎剂能够去除LY12铝合金表面复杂的氧化膜, 实现LY12铝合金的中温钎焊.研究发现: 改进的CsF-AlF3钎剂是以反应、溶解方式去除氧化膜的; 在去膜过程中, CsF化合物起主要去膜作用, 钎剂的高活性与NH4F、NH4AlF4及复合盐熔体等化合物的存在有关, 它们的存在可提高CsF-AlF3钎剂的去膜能力, 而HF的生成则是诱发和加速反应、提高溶解去膜能力的关键;微量稀土元素镧未在界面出现富集现象,微量的稀土氟化物则起着"助溶"的作用.

Mechanism of brazing flux reacting with oxide film of LY12 aluminum alloy

The technology for brazing LY12 aluminum alloy at middle temperature was realized by using CsF-AlF_3 no-cleaning flux that can remove the complicated oxide films on the surface of LY12 aluminum alloy. It is found that the improved brazing flux CsF-AlF_3 can remove the oxide film by way of reacting and/or dissolving the oxide film, and the compound CsF plays an important role in the course of removing the oxide film. The high activation of the flux has something to do with NH_4F, NH_4AlF_4 as well as other complicated molten salts, and the ability to removing the oxide film by the flux can be enhanced owing to the existence of above compounds. It is the key step that the formation of HF causes and speeds up the reaction of removing oxide film and promotes the ability to dissolving oxide film. No gathering phenomenon emerges on the surface of brazing seam for the trace rare-earth element La and the rare earth fluorides play "dissolving-aided" role in brazing.