Hot pressing of nanocrystalline TiO_2 (anatase) ceramics with controlled microstructure

摘要

The preparation conditions of nanocrystalline phase-pure TiO_2 anatase ceramics by hot pressing are described. Density, surface area, pore size distribution and grain size are determined by various techniques, including gas adsorption, mercury porosimetry, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The evolution of the structural parameters is followed as function of temperature and pressure programme. It is shown that the porosity, grain and pore size of the ceramics can be controlled by a suitable choice of experimental conditions. Ceramics with densities higher than 90 percent of the theoretical limit with a mean grain size of 30 nm can be obtained at temperatures as low as 490 deg C under 0.45 GPa for 2 h. The experimental results are discussed in view of the sintering theory.