Yield behavior of zirconia-wax suspensions

In this study, the yield stress (τ_y) of highly concentrated zirconia-wax suspensions is investigated in terms of temperatures (58.5-85°C), solid concentrations (50-65 vol.%), and average particle sizes, (0.085-0.25 μm). A linear correlation between τ_y and flow resistance parameter (defined as Φ/(A - Φ), where Φ 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 τ_y, which is primarily due to a decrease in the attractive interparticle potential. Such a temperature-dependent τ_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 τ_y. The attractive and repulsive interparticle forces which are primarily responsible for the overall behavior of suspension τ_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 τ_y determination as well in real suspension systems.