The preparation and characterization of Y-TZP/20 wt% alumina

Zirconia (+2-2·5 mol% yttria)/12-20 wt% alumina composite powders have been prepared by several techniques. The preparation methods were discussed in terms of powder characteristics, densification behaviour and microstructure. The densification behaviour of the composites depended on the crystal structure of the phases and on the dispersion of the alumina in the Y-TZP matrix. Both the spraying and coprecipitation methods resulted in an inhomogeneous dispersion and a relatively low density (95%), caused by either differential sintering of alumina aggregates (coprecipitation method) or by an inhomogeneous dispersion of the alumina (spraying method). Both the acetyl acetonate and the (alpha)-alumina methods resulted in high density (98%) ceramics in which the alumina was homogeneously dispersed. The (alpha)-alumina method, however, required higher sintering temperatures (1450°C) than the acetyl acetonate method. Both methods gave better results than those obtained with a commercially available powder.