Dispersion properties of alumina powders in silica sol

The dispersion of alumina powders in silica Sol has been investigated by ze ta potential, sedimentation, and rheological measurements. Zeta potential o f alumina in silica Sol changes significantly in comparison with that of al umina in deionized water. This is caused by the absorption of silica colloi dal particles with negative charge on the Surface of alumina particles. Sol -dispersed alumina slurry shows a minimum in sedimentation volume and visco sity around pH 10. The viscosity depends strongly on the silica Sol concent ration and reaches a minimum in 10-15 wt,% silica sols. It is proposed that the dispersion and stabilization of alumina particles in silica sol are at tributed to the electrostatic and steric effects of the colloidal particles absorption. Effects of pH, solids content and silica Sol concentration on the rheological behavior of sol-dispersed alumina slurries are discussed in detail. (C) 2001 Elsevier Science Ltd. All rights reserved.