DEPENDENCE OF COMPACTION EFFICIENCY IN DRY PRESSING ON THE PARTICLE-SIZE DISTRIBUTION

The compact densification with pressing pressure (compaction efficienc y) was determined to be sensitive to the particle size distribution, F or the three types of alumina powders used in this research, the.compa ction efficiency increased with increasing particle size. It has been demonstrated that if the compact density versus log (pressure) has a l inear relationship for any two types of powders, so do the blends of t he two powders. A model is proposed which can predict the compaction e fficiency of a binary particle system based on the Furnas particle pac king model and consider the packing efficiency as a function of formin g pressure. The composition of the binary mixture at which the highest density is obtained under high pressures is also the composition havi ng the largest compaction efficiency. When coarse particles were added to this composition, the compaction efficiency slowly decreased, and when fine particles were added, the compaction efficiency rapidly decr eased. For a continuous particle size distribution, the highest compac tion efficiency is related to the average value of -log (pore fraction ).