Effect of bimodal particle size distribution on compaction efficiency and sintering behavior of alumina powders

The effect of bimodal p;irticle size distribution on the compact efficiency and sintering behavior of submicron-sizcd alumina powder was investigated For two types of submicron alumina powders with size ratio of about 2, considerably higher compact densities, as compared to their individuals, were obtained when mixed in proper volume ratios. In the case of 33% fine partiels in the mixed powder, the relative green density of above 72% was achieved by pressure filtration. Different consolidation techniques, namely pressure filtration and drying press, were found to yield compacts with different properties. Green compacts by pressure filtration, which had higher density, narrower pore size distribution and smaller mean pore size than those by dry-pressing, can be sintered to theoretical density with fine microstructurc at relatively low temperature. The sintering behavior and the microstructure developed for the compacts by different compaction techniques were discussed with newly developed theory of sintering thermodynamics.