Spreading And Wetting Behavior And Interface Bonding Of Sn On Al Under Ultrasound

In this paper，the progess of spreading and wetting in system of Sn-basedsolder on aluminum alloys is summarized under the action of ultrasonic，thebonding mechanism driven by ultrasonic is also outlined in the view of TEM andHRTEM. The effot was focused on oxide film broken mechanism and bonding of Snand oxidation.In addition，the variation of spreading freedom and the promote roleof the ultrasonic in the process of the spreading was disscussed preliminary，whichlaid the foundation for wettability evaluation.Through the micro-arc oxidation treatment for the aluminum go for tophysically simulate the form of oxide film.The result shows ultrasonic contribute tothe change of the oxide film.The oxidation went through four stages，including thedeformation of oxide film、solder dissolved the base material、oxide film floated upand oxide film was broken，which proceed in the meantime until the oxide film wasremoved in the whole interface.Wettability of the pure Sn solder on pure Al board is evaluated under theaction of ultrasonic.We found that oxidation film was complete at the edges ofinterface，and the wetting angle was obtuse angle，which provoked the discussion ofthe wettability. Basing on the calculation of free energy in this system，we definesthe ultrasound additional energy WS，in view of this unique phenomenon wasdiscussed and calculated.Study found that thickness of aluminum oxide film is about200-400nm inthe natural brazing conditions，the oxide film is in disorder amorphous structure. ByTEM and HRTEM observation of the interface，no matter which one of M.AO. filmor oxide film，the results suggest that Sn-based and Zn-Al solder has combined withoxide film，no gap between them. and there is a amorphous layer joining the solderand the oxide film.