The influence of crystallization and washing medium on the characteristics of nanocrystalline Y-TZP

A zirconia-yttria gel, made by coprecipitation, was treated in six different ways to obtain a nanocrystalline Y-TZP powder: one large gel batch was split into six parts of which one was crystallized in air and the other crystallized either in water with a high pH or in methanol. The batches were subjected to several post treatments. Powder properties and densification characteristics of the six powder batches obtained in this way are described. The air-calcined powder can be sintered to a relative density of about 93% at 1070 degrees C/10 h, but reproducibility of the sintering characteristics is poor. Optimal hydro-thermal treatment of the powder yields a reproducible sintering process, resulting in a relative density of 96% at 1070 degrees C/10 h and an average grain size between 120 and 130 nm.