TETRAGONAL ZIRCONIA POWDERS FROM THE ZIRCONIUM N-PROPOXIDE ACETYLACETONE WATER ISOPROPANOL SYSTEM

As a part of a work concerning densification and toughening of silicate ceramic products, this paper describes the preliminary characterization of a zirconia precursor fabricated through a sol-gel route in the zirconium n-propoxide-acetylacetone-water-isopropanol system. When the molar ratio R = [acac]/[Zr] increases from R = 0 to R = 0.8, the precursor changes from a colloidal precipitate to a polymeric gel with an increasing gelation time. Drying and firing the precipitates leads to the monoclinic stable form of zirconia while the first crystalline phase obtained beyond 500-degrees-C from the gel is the metastable tetragonal one. Successive steps of the reactions are investigated by small angle X-ray scattering, differential thermal analysis, thermogravimetry and X-ray diffraction.