Flow kinetics in concentrated suspensions of silica-iron(III) oxide-water

Abstract

The flow properties of concentrated suspensions of silica and iron(III) oxide in water have been studied using a viscometer which was modified so as to prevent settling of the solid material. The effect of adding small quantities of metal oxides to silica slurries is often to thicken them and to increase the materials handling problems. The shear strain rate was considered to have two components owing to consecutively occurring events. Considerable analytical simplification was achieved compared with many methods in use and the flow could be described in terms of material parameters having clear physical meanings. The first component is Newtonian fluid flow in which the strain rate is governed by the diffusion of water. The second is a solid flow component which was analysed in the same way as thermally activated deformation in metals and involves two material parameters: an activation energy term and a flow stress. Apart from increased solid concentration effects, the only effect of adding iron(III) oxide appeared to be the introduction of a chemical potential term into the activation energy for the solid flow component.