抄録
Alumina fine powder which adsorbed a given amount of water was dispersed in a hydrophobic solution of n-hexane and ethyl silicate with a small amount of surfactant such as, fatty acid, alkyl amine or sorbitan monostearate (Span 60). Ultra-fine particles and a thin film of silica were formed on the alumina particles after being coated in the solution with stearic acid and stearylamine, respectively. The addition of Span 60 reduced the catalytic activity of stearic acid and stearylamine for the hydrolysis. The silica content of the powder after coating treatment in the presence of stearylamine was nearly equal to that calculated from the amount of water adsorbed on the alumina powder. The silica content was controllable up to 15wt.% by adjusting the amount of adsorbed water.
