COMPACTION BEHAVIOR OF AGGLOMERATED ALUMINA POWDERS

The effects of agglomerate properties, such as the binder type, binder content, moisture level, and agglomerate size, on a model compaction process was investigated by using green density-pressure interrelation ships for a range of agglomerated alumina powders. The model compactio n process involved single ended nominal uniaxial stress transmission i n a cylindrical die. The influences of the sample aspect ratio, die wa ll lubrication, and compaction rate were also investigated. Two types of water soluble polymeric agents, a poly(vinyl alcohol) (PVA) and a p oly(ethylene glycol) (PEG), were used. It was shown that certain agglo merate properties have a strong influence upon the compaction behaviou r of these ceramic powders. The extent of the compaction is enhanced b y using agglomerates with a low agglomerate yield point. In the PVA sy stem, the agglomerate yield points decreased with increasing moisture content. The compaction behaviour of the agglomerates showed a rate de pendency, that is, the compaction is retarded with increased pressing rate. The green densities of the compacts prepared in the unlubricated die were lower than those of the compacts prepared in the lubricated die due to the higher wall frictional forces operating in the unlubric ated die.