Yield behavior of zirconia-wax suspensions

In this study, the yield stress (tau(y)) of highly concentrated zirconia-wax suspensions is investigated in terms of temperatures (58.5-85 degrees C), solid concentrations (50-65 vol%), and average particle sizes, (0.085-0.25 mu m). A linear correlation between tau(y) and how resistance parameter (defined as phi/(A - phi), where phi is the solid concentration and A is the apparent maximum solid concentration) for each suspension system is empirically established. Increase in temperature causes a decrease in tau(y), which is primarily due to a decrease in the attractive interparticle potential. Such a temperature-dependent tau(y) becomes more pronounced as the solid concentration is increased. Decrease in the particle size gives rise to an increase in attractive force, which results in an enhancement of suspension tau(y). The attractive and repulsive interparticle forces which are primarily responsible for the overall behavior of suspension tau(y) can be estimated quantitatively and separately. The change in the relative magnitude of these interparticle forces of different nature with temperature is the same as the yield value of the suspensions. The methodology proposed in this study appears to provide a valuable alternative for interparticle force and tau(y) determination as well in real suspension systems. (C) 1998 Elsevier Science S.A. All rights reserved.