The effect of alumina content on the structural properties of ZrO2-Al2O3 unstabilized composite nanopowders

In this research, a sol-gel process was used to synthesize zirconia-alumina (ZrO2-Al2O3) composite nanopowders containing 10, 20, and 50 mol% alumina (Al2O3) without any stabilizer. Zirconium acetate hydroxide and aluminum isopropoxide were employed as precursors. The produced composite nanopowders were characterized using a Brunauer-Emmett-Teller (BET) surface area analyzer, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric/differential thermal analysis, X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The BET results showed a decrease in surface area and average particle size and an increase in pore size with increasing Al2O3 content. FTIR, in corroboration with XRD, confirms the crystallization of corundum (alpha-Al2O3) as one of the alumina phases. The X-ray studies showed that an increase in Al2O3 content shifted the tetragonal zirconia (t-ZrO2)-phase crystallization to higher temperatures. Microstructural characterization by SEM depicted that the particles tend to be more agglomerated with increasing Al2O3 content.