Influence of alumina-slurry-dispersion characteristics on microstructure of granules and uniaxially pressed green bodies

Conditions of slurry preparation and granule production processes influence the properties of grannies produced from the slurry. In this study, alumina slurries of different amounts of dispersant (from 0.1 to 0.8 mass%) were prepared to change the dispersion state. Granules were prepared from these slurries by using a spray-dryer to obtain granules of different microstructures. The relationship between microstructure of granules and green bodies compacted from the grannies is discussed. As the amount of dispersant decreases, granules become weak and fragile, but uniform. The granules with high amounts of dispersant are strong, tough, and difficult to break. Uniaxially pressed green bodies from grannies with high addition of dispersant, i.e., strong granules, contain defects such as granule traces and crescent-shaped irregular distribution of density. The defects come from the original shape of granules.