Abstract:The dependence of sinterability on the state of agglomeration of ultrafine ZrO₂(Y₂O₃) powders prepared by coprecipitation was investigated. The results showed that the powder prepared by direct drying and calcination of the water-washed gels was poorly sinterable with sintered density as low as 89% of theoretical value. The powder sinterability could be markedly improved by ball milling, and the sintered density could be increased to 96% of theoretical value under the same sintering condrtions.Highly sinterable powders were prepared by adding some surfactants or by alcohol dehydration before gel drying, and the relative sintered densities greater than 985% were obtained. Sinterability mainly depended on the state of agglomeration of powders. The relation between sintered density and the state of agglomeration of powders was discussed.

Key words: zirconia; ultrafine powder; agglomeration; sinterability