Electroacoustic and rheological properties of aqueous Ce-ZrO2 (Ce-TZP) suspensions

Ce-ZrO2 (13 mol% CeO2) powder was found to be slightly soluble under acidic conditions and the isoelectric point was determined to be pH(iep) = 7.9 using electroacoustics in concentrated suspensions. The adsorption isotherms of two well-characterized polyelectrolyte dispersants, Dispex A40 and Duramax D3007, were related to the molecular structure. The fully ionized polyacrylic acid (Dispex A40) adsorbed in a flat conformation on the Ce-ZrO2 powder; while the Duramax D3007 displayed higher adsorbed amounts which was attributed to possible multilayer adsorption caused by the zwitterionic nature and the existence of hydrophobic parts of the Duramax D3007. If was found that the viscosity is at a minimum at monolayer coverage of the dispersant when the polyelectrolyte-covered particles are highly negatively charged. The study illustrates how rheology and electroacoustics can be utilized in the investigation and optimization of the properties of concentrated ceramic suspensions. (C) 1997 Elsevier Science Limited All rights reserved.