High velocity interparticle collisions driven by ultrasound

Ultrasonic irradiation of slurries produces high velocity impacts between solid metal particles that are sufficient to cause interparticle melting. Sonication of 5 μm Zn powder as a slurry in alkanes, for example, produces dense agglomerates 50 μm in diameter consisting of ∼1000 fused particles. Particle size was found to be the most influential parameter in inducing local melting during interparticle collisions. Ultrasonic irradiation of mixed powders resulted in formation of agglomerates with larger Zn particles soldered" by the smaller ones. A simple kinematic model of the ultrasound-driven interparticle fusion predicts a melting criterion that is nonmonotonically dependent on particle size and is shown to be in agreement with experiment. Copyright © 2004 American Chemical Society."