PREPARATION OF MONODISPERSED ZIRCONIA-ALUMINA AND YTTRIA-ALUMINA PARTICLES

Alkoxide route involving the use of an emulsion technique enabled monodispersed, spherical zirconia-alumina and yttria-alumina particles of submicrometer size to be formed. The effects of the concentration of reactants and their ratio, organic solvents, and HPC dispersant on particle size, size distribution, morphology, and aggregation were investigated. EDS analysis showed little particle compositional fluctuation. Unstabilized tetragonal zirconia was retained in an alumina matrix up to 15 mol% zirconium alkoxide content at 1400 degrees C. Yttrium aluminum garnet was formed in yttria-alumina powders calcined at 1000 degrees C. The calcination at 1000 degrees C also resulted in particles that retained their spherical morphology. The isoelectric point of zirconia-alumina and yttria-alumina particles occurred from pH 9 to 10.