ON THE EFFECT OF LOCAL VARIATIONS IN DENSITY IN MONOLITHIC CERAMIC BODIES

A16.SG alumina bars were pressed to different densities. Samples of tw o selected bars were used to create high- or low-density regions at th e centre of pressed discs. These discs were sintered by heating to 160 0-degrees-C. The densities of the discs and each region contained in t hem were determined before and after sintering. The defects and the mi crostructure at the interface separating the low- and high-density reg ions in the sintered specimens were studied using X-radiography and mi croscopy. Differential sintering was observed in both types of discs. In addition, the presence of a high-density region in a low-density ma trix caused radial cracking and a pronounced difference in grain size at the interface.