Characteristics And Effects Of The Ultrasonic Cavitation In The Thin Layer Of Liquid Metal

This paper mainly studies the ultrasonic cavitation in the liquid metal which in thenarrow gap. The purpose is to reveal the physical phenomena among the ultrasonicassisted soldering and explain the cause of oxide film dissociated from the base metal. Itwill enrich the theory of ultrasonic assisted brazing.First high-speed camera is used to observe the cavitation bubbles in the pool filledof solder. We mainly observed the form and distribution of cavitation bubbles andanalysis its characteristics changed with time. The factor of influencing cavitationincluding gap, amplitude and solder type is studied in this paper. The size of aluminumplate is80×30×3mm which is milled a solder poll in side of plate. The solder poll iscovered with transparent glass in order to see the cavitation bubbles inside the metal.The form of cavitation bubbles are main transient cavitation bubble and the quantity ofbubbles are more in middle than side. In the transient time the cavitation bubbles do notappeared at all positions. But in a period of time it substantially appears at all areas.The core issue of ultrasonic soldering is the removal of the oxide film. Theultrasonic soldering is utilizing this point to weld some materials which is hard to weld.The process of dissociating the oxide film is microcracks-cavitation-hole-theamplification of cavitation hole-oxide film dissociated completely. The factors ofinfluencing cavitation erosion are also studied.The amplitude distribution is used ANSYS to simulation and the distribution ofsound pressure inside the gap is used FLUENT to simulation. It explains the phenomenathat the distribution of cavitation bubbles and erosion pit. We argue that the largeramplitude of plate lead to the higher acoustic pressure in the gap, that resulting thestronger cavitation effect.