Synthesis of Nanocrystalline á-Al_2O_3 from Nanocrystalline Boehmite Derived from High Energy Ball Milling of Gibbiste

摘要

Dry milling of gibbsite has been carried out for 5 h in planetary ball mill to study the effect of mechanical activation on á-Al_2O_3 formation. Gibbsite undergoes phase transformation during milling and has resulted nanocrystalline boehmite after 5 h of milling. The average crystallite size and the BET surface area of the nanocrystalline boehmite resulted by 5 h milling of gibbsite are 8 nm and 140 m~2/g, respectively. The nanocrystalline boehmite has shown reduction in the á-Al_2O_3 formation temperature as well as in the activation energy of á-Al_2O_3 formation. The average crystallite size of nanocrystalline boehmite derived á-Al_2O_3 is measured to be 100 nm by TEM analysis and the BET surface area of resulted nanocrystalline á-Al_2O_3 is 12 m~2/g.