Influence of Stirring on Incorporation of Particles during Solidification

Abstract
The critical freezing rate Vc was measured for glass beads suspended in naphthalene by using the tilt rotating zone melting technique. In horizontal operation with a large gas bubble sweeping along the interface during rotation, Vc increased dramatically with increasing tube rotation rate and decreasing mass of beads. Tilting the tube prevented the bubble from contacting the freezing interface and very stongly increased Vc . Siliconized glass beads were pushed as well as nontreated beads, both in horizontal operation with tube rotation and in vertical operation without stirring. Teflon particles were pushed to very high freezing rates in the horizontal rotating configuration. These results differ from those of Omenyi and Neumann, who predicted and observed that both Teflon and siliconized glass beads are not pushed by freezing naphthalene at any freezing rate.