Structural, physical and mechanical properties of zirconia-polymorph/alumina composites

The effect of zirconia polymorphs on the structural, physical, and mechanical properties of zirconia composites reinforced with various contents alumina was studied. The zirconia polymorphs exhibited amorphous (aZ) and tetragonal (tZ) phases, which were obtained by processing natural zircon sand, and the alumina (A) was a commercial product. The mixture of zirconia and alumina was mechanically activated and sintered at 1400 degrees C for 3 h. The elemental analysis and phase analysis of the purified zirconia powder was performed via X-ray fluo-rescence spectroscopy (XRF), and X-ray diffraction (XRD). Characterization of the composites included diameter shrinkage, density, and Vickers hardness. The atomic diffusivity in the interfacial region between each element was also observed based on the EDX line analysis. The results show that the amorphous zirconia powder con-tained 81.1% Zr with Si and Ti being dominant impurities. However, the identified phases were amorphous and tetragonal for zirconia raw powder respectively. Further analysis of the composite phase exhibited new phases such as zircon, monoclinic zirconia, and mullite. The aZ/A 90:10 sample had the largest shrinkage in pellet diameter, apparent density, and Vickers hardness, at 20.8%, 4.40 g/cm(3), and 6.07 GPa, respectively.