Apparatus and method for generation of microspheres of metals and other

Abstract

Apparatus and methods for making uniformly-sized and predictably-spaced droplets or solid microspheres from high-temperature or other liquids. Liquid droplet generators having electromechanical driving elements are coupled to a power supply to apply pulsed excitation forces through a wall of a delivery tube to a liquid, e.g., a liquid metal, epoxy, or polymer. The excitation forces generated by the driver induce capillary vibrations in the liquid within the delivery tube, which breaks the stream into substantially uniformly-sized liquid droplets shortly after leaving the orifice. Droplets may be produced in a uniformly-spaced series, or individually on demand in response to a single burst of force from the driving element. If solid microspheres are desired, the trajectory of the emitted droplets is determined to permit the solidification prior to catching or collecting the microspheres. Solidification of the spherical drops may be accomplished by freezing, evaporation, or chemical reaction due to heat transfer, material transfer, or chemical reaction as the droplets traverse a controlled environment chamber. To permit collection of the microspheres with controlled material properties and without deforming or otherwise changing either the sphericity or surface quality, the flight path environment is controlled to bring the drops to a very low speed prior to collection of the solidified microspheres.