Preparation of Monodisperse, Spherical Alumina Powders from Alkoxides

Monodisperse, spherical alumina powders were prepared by the controlled hydrolysis of aluminum alkoxide in a dilute solution consisting of octanoi and acetonitrile. The reagent concentration influenced the particle size, size distribution, morphology, and state of agglomeration. The addition of acetonitrile and octanol affected both particle shape and the state of agglomeration and prevented gelation during hydrolysis. Sub-micrometer-sized alumina particles grew to 10 μm with increased concentration of hydroxypropylcellulose dispersant. As-prepared amorphous powders crystal-lized to γ-alumina at 1000°C and converted to α-alumina at 1150°C without intermediate phases. The particle morphology was retained after crystallization to γ-alumina.