抄録
The sintering process of titanium dioxide derived from alkoxide was investigated by means of dilatometry, X-ray diffraction, electron microscopy and the measurement of isothermal shrinkage. 1) Titanium oxide (anatase, +brookite) prepared by calcining the as-prepared material at low temperatures (300°-500°C) was highly sinterable. The sintering process was composed of two stages: a rapid shrinkage at 400°to 680°C and a gradual shrinkage above 900°C. The sintered bodies as high as 98% of the theoretical density were obtained by heating at 1400°C.
2) The sintering mechanisms were studied at the temperatures ranging from 450°Cto 680°C. At 450°C to 550°C, the process was expressed with the linear relation between log (shrinkage) and log (time) with a slope of unity, and was thought to be the rearrangement process of primary particles. This process was followed by the process with a different slope due to volume diffusion. The activation energies were about 9.6 kcal/mol for the rearrangement process and 116.7 kcal/mol for the volume diffusion, respectively. At 550°to 680°C, no shrinkage was observed except for the initial rapid shrinkage due to the rearrangement process.
3) In the sintering of rutile prepared by calcining at 800°C, the rearrangement process was also predominant at the initial stage followed by grain boundary diffusion. The apparent activation energy for the latter was about 78 kcal/mol.
