Synthesis and Densification Studies of Nanocrystalline Titanium Dioxide Ceramics

In this research, we have synthesized nanocrystalline titanium dioxide (TiO 2 ) ceramic powder through a simple process of hydrolyzing titanium tetraisopropoxide (TTIP) in a mixture of isopropanol and deionized water, and studied its densification behavior. Nitric acid (HNO 3 ) was added to restrain the hydrolysis process, and consequently to control the grain growth. The synthesized powder was analyzed for its phases, using the X-ray diffraction technique. Transmission electron microscopy (TEM) was used to determine its powder particle-size and morphology. Dense structures, made from the synthesized nanocrystalline powder and commercial TiO 2 powder (Alfa Aesar Company, 99.9% pure), were sintered in the temperature range of 1200-1400°C, to study and compare their densification behavior. Vickers hardness test was carried out to evaluate their mechanical property. Results showed that the synthesized TiO 2 powder was in anatase phase and its particle-size was around 5∼10 nm. For both kinds of TiO 2 ceramics, the densification process continued with an increase in sintering temperature and the nanoscale TiO 2 exhibited improved sintered density, compared to the commercial powder at all sintering temperatures. We also observed that at a sintering temperature of 1200°C, the volume shrinkage of nanocrystalline TiO 2 samples was 49%, while only 27% was observed in commercial TiO 2 samples. The trend of variation in hardness of the sintered structures with the increase in sintering temperature (1200 - 1400°C), was similar with that of the densification studies. Maximum hardness value of 328.3±16 HV was obtained in specimens sintered at 1400°C.