Interaction of Aluminum-Iso-Propoxide Solution and Si<sub>3</sub>N<sub>4</sub> Powder

Abstract

The dispersability of Si3N4 powder in n-C6H14 and Al(Oi-Pr)3/n-C6H14, and the amount of Al(Oi-Pr)3 adsorbed on the surface of Si3N4 particles after mixing Al(Oi-Pr)3/n-C6H14 and Si3N4 were examined. The zeta-potential of the powder prepared by spray-drying and calcining a mixture of Al(Oi-Pr)3/n-C6H14 and Si3N4 was measured. The dispersablity of Si3N4 in Al(Oi-Pr)3/n-C6H14 was much higher than in n-C6H14, due to the formation of-Al(Oi-Pr)n layer on Si3N4 particle surfaces. The Si3N4 powder which was separated from the mixture of Al(Oi-Pr)3/n-C6H14 and Si3N4 by filtration after hydrolysis by addition of water and peptization by addition of diluted HCl at pH 2, contained 0.07wt% Al. The isoelectric point of the powder which was prepared by spray-drying and calcining the mixture of Al(Oi-Pr)3/n-C6H14 and Si3N4 was about 8.2, while that of Si3N4 was 5.5. These results suggested that Si3N4 particles were coated with a γ-Al2O3-like layer.