THE PREPARATION AND CHARACTERIZATION OF Y-TZP 20WT-PERCENT ALUMINA/

Zirconia (+2-2.5 mol% yttria)/12-20 wt% alumina composite powders have been prepared by several techniques. The preparation methods were dis cussed in terms of powder characteristics, densification behaviour and microstructure. The densification behaviour of the composites depende d on the crystal structure of the phases and on the dispersion of the alumina in the Y-TZP matrix. Both the spraying and coprecipitation met hods resulted in an inhomogeneous dispersion and a relatively low dens ity (95%), caused by either differential sintering of alumina aggregat es (coprecipitation method) or by an inhomogeneous dispersion of the a lumina (spraying method). Both the acetyl acetonate and the alpha-alum ina methods resulted in high density (98%) ceramics in which the alumi na was homogeneously dispersed. The alpha-alumina method, however, req uired higher sintering temperatures (1450-degrees-C) than the acetyl a cetonate method. Both methods gave better results than those obtained with a commercially available powder.