Dispersion behavior and stabilization mechanism of alumina powders in silica sol

The dispersion behavior of alumina powders in various concentrations of silica sol was investigated by sedimentation tests and rheology measurements. Meanwhile, the stabilization mechanism was studied based on TEM observation for the sediment and measurement of the silica concentration in the supernatant. It is proposed that the dispersion and stabilization of alumina particles in silica sot are attributed to the nanoparticle halo formation around the alumina particles, where the silica colloidal particles are highly dispersed at about pH 9.5. The stabilization mechanism is discussed and explained by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the deduced nanoparticle halo model. (C) 2004 Elsevier B.V. All rights reserved.