Synthesis of monodisperse ZrO2 microspheres via urea homogeneous precipitation and its effect on the sintering properties

Abstract

Monodisperse zirconia microspheres were prepared by homogeneous urea precipitation method. The effect of reaction time, reaction temperature and other synthetic parameters on the dispersion of the product was investigated in this experiment. The as-prepared zirconium oxide (ZrO2) powders were characterised by X-ray diffraction, Brunauer–Emmett–Teller analysis, field emission-scanning electron microscopy and Fourier-transform infrared spectroscopy. The experimental results show that the size and dispersion of ZrO2 microspheres can be controlled by changing the concentration of polyvinylpyrrolidone (PVP). The size of ZrO2 microspheres is changed from 120 nm to 1 μm with the increase of PVP concentration. When the reaction temperature is raised to 90°C and the reaction time is reached to 2 h, the monodisperse ZrO2 microspheres with a diameter of 120 nm are finally prepared. ZrO2 ceramics possessed an ultrafine, uniform microstructure and a narrow pore size distribution, and the grain size increased from 72 to 190 nm with the increase of sintering temperature. Moreover, when ZrO2 ceramics were sintered at 950°C for 2 h, the theoretical density was up to about 98% (a density of 5.65 g/cm3), which is higher than that of conventional ZrO2 ceramics.