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Abstract The a-A12O3 nanopowder was prepared by sol-gel method with industrial pure alumina sol as starting material. The effects of peptization condition, addition of seed crystal, addition and kinds of kinds of,calculation temperature and holding time on the crystal grain size of nano- A12O3 were investigated. The results show that the smaller the particle size after peptization is, the smaller the particle size of product is, and the lower the calcination temperature is. The addition of seed crystal and additive can accelerate the transition alumina changing to a-A12O3, and reduce the phase transformation temperature. The calcination temperature greatly influence the formation of a-A12O3, whereas the holding time has little effect on the phase of product. The spheric granules a-A12O3 nanopowders with 50 nm particle size and with even size distribution are obtained under the optimum condition of 1 wt% triethanolamine, 5 wt% sieve crystal, 5 wt% NH4 NO3addition, 1000 oC for calcination temperature and 2 h holding Time.
Sol-gel method preparation instrument a-A1203 nano powder
A-A12O3 nanopowders were prepared by sol-gel method using industrial alumina sol as raw material. To study the effects of gel conditions, seed addition, mineralizer type and addition amount, calcination temperature and holding time on the product. The results show that the smaller the particle size after sol degumming, the smaller the particle size of the product, the lower the calcination temperature required to obtain the product; the introduction of seed crystals and mineralizer can promote the conversion of transition alumina to a-A12O3. The phase transition temperature is lowered; the calcination temperature has a great influence on the formation of aA12O3. When the temperature is constant, the prolonged holding time has little effect on the product phase. The optimum conditions for preparing a-A12O3 nanopowder by sol-gel method are: the dispersant triethanolamine is used in an amount of 1% (mass fraction), the seed crystal is added in 5%, the NH4NO3 is added in 5%, and the calcination temperature is 1000oC. The holding time is 2 h. The obtained a-A12O3 nano-powder has a spherical appearance, uniform particle size distribution and a particle size of about 50 nm. (Diamond and Abrasives Engineering, 2009, Issue 1)