Effect of Water Content on Semi-Dry Press Forming for Ceramics Granules
Yayoi TAKAHASHI,Satoru JOGAN,Haruhisa SHIOMI and Masatoshi SATO
Abstract:Semi-dry press forming using ceramics granules with plasticity due to large amount of water was attempted. The granules with a fair amount of water were prepared using a stirring granulator and compared with the spray-dried granules generally used for press forming. In order to investigate the compaction behavior of the granules, press forming was carried out under various pressures. The relative density of a compacted body increased with increasing water content of the granules. The pressure dependence of the relative density of the powder compact was small in the case of the high water content granules. The granules containing large amount of water had a loose agglomerate structure, so they were easily deformed and crushed at low pressure. On the other hand, dry granules were hardly deformed because of their rigid agglomerate structure. Therefore, the volume change of the granules containing much water during pressing was larger than that of the dry granules, resulting in high relative densities of powder compacts at low pressure. Moreover, in the case of wet granules, the firing shrinkage of the powder compact was independent of forming pressure and homogeneous sintered bodies were obtained even at low forming pressure. Key Words:Stirring granuleCSemi-dry press formingCCompaction behaviorCPowder compactCAgglomerate structure