Sintering behaviour of Y 2O 3 powders prepared by the polymer complex solution method

Abstract

High purity fine Y 2O 3 powder has been prepared by a polymer complex solution method using polyethylene glycol as the complexant of Y 3+ cations. Powder morphology and compacts prepared from three different powder characteristics have been studied. SEM observations were used to know the agglomeration degree of the powders, and the uniformity of powder compacts, and the Hg-porosimetry results to investigate the pore size and microstructure evolution during sintering of the green compacts. The compacts made with the powders calcined at the lower temperatures showed an almost single-peaked pore-size distribution and a more homogeneous microstructure, whereas the pore-size distributions of the compacts made with powders calcined at higher temperatures were double or triple peaked. The sintering behaviour of the low temperature calcined powders exhibited significantly better sinterability and higher densification rate/grain growth rate ratio than the high-temperature calcined powder compacts. Complex rearrangement phenomena relating the pore coordination numbers-grain size-grain morphology appear to occur in the initial and intermediate stages of sintering. In the final stage of sintering, grain growth modified the thermodynamic stability of remaining pores permitting its disappearance although kinetics impeded its complete elimination limiting, thus, the final density to values near theoretical density (≈99.5%).