Monosize droplet deposition as a means to investigate droplet behavior during spray deposition

A Rayleigh atomization technique is employed to produce streams of evenly spaced, monosized droplets of molten metal. We study the effects of variations in selected process parameters upon the droplet formation mechanism and the morphology and microstructure of resulting deposits. Initial tests with alcohol jets show that changes in the flow velocity, drive frequency, and destabilization amplitude have a significant effect upon the efficiency of droplet formation and the uniformity of the droplet stream. For instance, an integer-multiple increase in the flow velocity shifts the frequency threshold for stable jet breakup by an integer multiple of its original value. In addition, the optimal frequency range broadens at higher flow velocities. Microstructural studies on Sn/Pb droplets formed using this approach show signs of rapid solidification.