Nano Of Tio <sub> 2 </ Sub> Preparation Of Sio <sub> 2 </ Sub> And Al <sub> 2 </ Sub> The O <sub> 3 </ Sub> In Situ Surface Coated With Anti-reunion

It is generally considered that the aggregation of powder is one of the biggest problems in the preparation of nano-TiO₂ powder by liquid-phase method. The control of aggregation has been a key technology for the preparation of high quality nano-materials.In order to get rid of the shortcomings of current anti-aggregation technology, a new method is developed. The inorganic oxide layer is coated in-situ on the surface of titanium dioxide precursor TiO₂·nH₂O in the way of heterogeneous nucleation. Uniformly dispersed nano-powder is obtained so that the hard aggregation of nano-TiO₂ is inhibitted effectively. A systematic research on the dispersibility, morphology, granularity, surface structure and thermal stability of coated sample is investigated by using TEM, SEM, XRD, BET, FT-IR, XPS. Some innovative results are summerized as following:1) H₄TiO₄ was in-situ coated with Al₂O₃ by heterogeneous nucleation process. The results show that the dispersibility of powder can be improved apparently with Al₂O₃ layer coated and the hard aggregation is inhibited effectively. Particles in the size of 50 nm are prepared. The thermal stability of the composite powder could be enhanced by coated 5 or 10wt% uniform layer.2) Reserch of H₂TiO₃ in-situ coated with SiO₂ and Al₂O₃ layer is conducted respectively. The technical parameters which influence coating process is investigated by analysing the morphology and surface structure separately. The results show that the dispersibility of powder improved and hard aggregation reduced. The particle size of the composite powder is determined to be within the size of 10²0nm from the image of TEM. XPS analysis indicates that SiO₂ and Al₂O₃ adhere to the TiO₂ surface by Si-O-Ti and Al-O-Ti chemical bond respectively.3) Surface property of nan-TiO₂ is changed after it coated with an organic dioxide layer. Aggregation can be reduced by depressing thegravitation among the nano-TiO2 particles. The developed coating technology for TiO2 is introduced into the process of nano-TiO2 prepararion and in-situ coating is achieved successfully.