INFLUENCE OF FORMATION PH AND GRINDING OF PRECURSORS ON COMPACTION AND SINTERING BEHAVIORS OF 3-MOL-PERCENT Y2O3-ZRO2

Tetragonal stabilized zirconia samples, 3 mol % in Y2O3, are prepared by pyrolysis up to 900-degrees-C of gelatinous precursors formed by hydrolysis of aqueous solutions containing both zirconium and yttrium acetates. Such prepared powders are white, but still contain about 0.5 wt % in carbon. The increase of the end hydrolysis pH from 3.9 to 10.0 has a very limited influence on the evolution of the density of samples during cold compaction and then sintering by heating at 1500-degrees-C The ball-milling of the precursor before pyrolysis decreases the size of the agglomerates formed at 900-degrees-C without modifying the size of crystallites. The size of large interagglomerate pores is also decreased The whole porosity remains constant and only the distribution between open and closed porosity is modified. The modification of the morphology eases the gaseous release during heating and leads to a more significant shrinkage and consequently to a higher density after sintering.