Sintering of Fine Oxide Powders: I, Microstructural Evolution

Microstructural evolution during sintering has been investigated using fine powders of CeO 2 and Y 2 O 3 with excellent sinterability. A universal pore size distribution, normalized by particle size, has been determined and found to be a function of density only. Microstructure evolves toward the universal distribution, with or without densification, signifying homogenization at all stages. This may even involve the elimination of supercritical pores, at low densities, which are otherwise thermodynamically not sinterable. Theoretical justification for these observations is made by using a network model with a random, but spatially homogeneous, distribution of spherical particles. Final microstructure after full density is reached is also found to evolve toward a universal steady state of grain shape/grain size distribution regardless of initial state.