Influence of Precipitating Atmosphere on Sintering of ZrO ₂ +12 Mol% Y ₂ O ₃

Abstract

Solid solutions of ZrO 2 and Y 2 O 3 prepared by decomposing coprecipitated hydroxides exhibited differences in sinterability which did not correlate with variations in particle size, surface area, or purity. These differences were traced to the fact that some of the materials had been exposed to CO 2 during preparation, whereas others had not. The presence of CO 2 during precipitation stabilized the amorphous phase such that energy release and the onset of nucleation and crystal growth occurred at a higher temperature than in Ar‐prepared material. It is suggested that during preparation in CO 2 a carbonate complex is formed, which decomposes on calcination, liberating CO 2 , some of which is trapped in voids formed by microsintering. The pressure of CO 2 in the voids limits their removal.