Surface and rheological properties of oxide dispersions under the influence of adsorbed metal ions hydrolysis products

Abstract

The effects of hydrolyzable Cu^2+, C0^2+, Ne^+ and Zr^4+ ions on the zeta potential and yield stress behaviour of silica and zirconia dispersions were evaluated as a function of pH. Silica dispersion remained dispersed at its point of zero charge of pH -1.0. Adsorption of metal ions hydrolysis products caused the silica dispersion to flocculate. Flocculation corresponded to the pH of fonnation of hydrolysis products. The interparticle forces arising from adsorbed hydrolysis product was measured using a rheological vane yield stress technique. The attractive forces contributing to the yield stress are van der Waals, charged patch and bridging.