Morphological changes in process-related large pores of granular compactedand sintered alumina

Large pore defects clearly develop in Al2O3 ceramics during sintering, Thes e large pores originate from voids caused by the incomplete deformation and adhesion of powder particles in collapsed dimples at the centers and bound aries of granules in the green compacts. The coalescence of pores, with lim ited shrinkage, during densification and grain growth in the late intermedi ate to final stages of sintering, is considered responsible for the develop ment of the large pores. The mechanism of pore coalescence is explained by thermodynamic arguments, which demonstrate that the largest pores result in a stable system.