Ceramics-Silikáty 53 (3) 205-210 (2009)

ELABORATION AND CHARACTERIZATION OF MULLITE-ZIRCONIA COMPOSITES FROM GIBBSITE, BOEHMITE AND ZIRCON

H. Belhouchet, M. Hamidouche, N. Bouaouadja, V. Garnier, G. Fantozzi

In this study we prepared mullite-zirconia composites by reactive sintering of gibbsite and boehmite as alumina sources and zircon powder. All raw materials have been ball milled and isostatically pressed followed by sintering in the temperature range of 1400-1600°C during 2 h of soaking. Then the sintered samples have been characterized by X-ray diffraction, ATD/TG analysis and microstructural observation. X-ray diffraction peaks showed the formation of mullite-zirconia compo-sites in both mixtures. The microstructure of all composites was composed of irregularly shaped mullite grains and round-shaped zirconia grains, which are distributed intragranularly and intergranularly. These microstructures had microcracks in the samples prepared from gibbsite and zircon, contrary to the samples prepared from boehmite and zircon where no microcracks were present. These microcracks are caused by evaporation of structure water at 300°C. So the preparation of mullite-zirconia composites with the substitution of the α-alumina by the boehmite is feasible.

Keywords: Gibbsite, Boehmite, Mullite-zirconia, Reaction-sintering, Composites, Microcracks