NEW METHOD FOR EFFICIENT COLLOIDAL PARTICLE PACKING VIA MODULATION OF REPULSIVE LUBRICATING HYDRATION FORCES

A simple method is described for increasing the viscosity of dispersed (20 vol ‥alumina) suspensions over 4 orders of magnitude through weak aggregation with certain indifferent electrolytes containing hydrolyzable anions. Particles in the viscous slurry, which are covered with short-range repulsive hydration layers, can be packed to a high density during pressure consolidation by apparent lubrication-assisted particle rearrangement. A combination of short-range (<5 nm) repulsive (lubricating) hydration force and longe-range attractive van der Waals force explains the observed viscosity-consolidation behavior of these slurries. This method provides an alternate to the presently used formulations for stabilizing concentrated colloidal slurries used in the processing of structural ceramics. © 1990, American Chemical Society. All rights reserved.