SYNTHESIS AND SINTERING BEHAVIOR OF A NANOCRYSTALLINE α-ALUMINA POWDER

摘要

Nanocrystalline α-alumina powders with a primary mean particle diameter of 10 nm were syn- thesized from aluminum nitrate and ammonia solution using a precipitation method. The presence of am- monium nitrate(a by-product of the precipitation reaction)in the Al(OH)_3 dry gel can reduce the formation temperatures of γ-,δ-,θ-,and α-Al_2O-3 during heating. The combined effect of wt/100 α-alumina seed crystals, 100 nm in diameter, and 44/100 ammonium nitrate can reduce the θ-Al_2O_3→αAl_3O_3 trans- formation temperature from 1200 to 900 deg. C.