Investigation of the powder characteristics and microstructures of alumina-zirconia composites

The electrokinetic properties of selected commercial ZrO2 and Al2O3 powders in aqueous suspensions were analysed. The relationship between the colloidal interactions in heteroparticulate powder mixtures and the rheological behaviour of appropriately concentrated real ceramic suspensions was examined, and related to the homogeneity of distribution of alumina and zirconia grains in the sintered microstructures. O2 powder grades investigated, although of nominally the same chemical and phase composition, differed not only in their specific surface area but also in their electrokinetic properties in aqueous suspensions. It is presumed that these differences result from the presence of active groups on the powder surface due to different powder calcination temperatures. the preferential adsorption of foreign ions contributes substantially to the powder surface properties of ZrO2 as measured by microelectrophoresis, the zeta potential vs. pH behaviour of these zirconia powders cannot be used to predict the colloidal compatibility with alumina in mixed concentrated suspensions.