Effect of Moisture on the Structure and Fracture Strength of Ceramic Green Bodies

To study independently the effects of moisture on the structure and the mechanical strength of the binder in green bodies, specimens of the system alumina/PVA were formed with spray-dried granules of various moisture contents. The structure and fracture strength of these specimens then were examined after their moisture contents had been adjusted to specified values. As moisture content increased in the granules during compaction, the density and strength of the green body also increased. The accompanying change in the fracture mode, from intergranular to transgranular, showed that the strength of the green bodies was affected more significantly by bonding between granules than by bonding between powder particles.