OSTWALD RIPENING OF SOLID-LIQUID PB-SN DISPERSIONS

An experimental study on the influence of a finite volume fraction of solid on Ostwald ripening of Pb-Sn dispersions is presented. Dispersio ns of lead particles in a near-eutectic Pb-Sn liquid were stabilized a gainst gravitationally induced sedimentation by the use of Lorentz for ces. The Lorentz forces were induced by an electrical current within t he samples and a magnetic field perpendicular to it. Dispersions from 0.3 to 0.71 vol fraction solid Pb could thus be kept free of any large -scale sedimentation for times of minutes to 15 hours. The results sho w that there is a definitive effect of the volume fraction on the rate of coarsening and that the experimentally measured kinetics are in cl ose agreement with theoretical predictions. However, it is also clear that Lorentz forces accelerate the coarsening process whenever a solid skeleton of the dispersoids is present. It is unclear if this acceler ation is also present in the experiments with a low volume fraction of solid.