Hollow ceramic microspheres by sol-gel dehydration with improved control over size and morphology
AssigneeThe Board of Trustees of the University of Illinois
InventorsDavid L. Wilcox, Jay G. Liu, Jee-Loon Look
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Abstract
Hollow microspheres of ceramic material are formed by a sol-gel technique involving forming and stabilizing an emulsion of an aqueous sol of the ceramic material in an organic phase, followed by dehydration of the stabilized emulsion droplets by extraction using a water-absorbing organic liquid, to form hollow gelled spheres, and finally recovery, drying and calcination of the spheres to the final product. The separation of the emulsion formation and dehydration steps into two distinct stages results in the ultimate formation of microspheres with improved uniformity and size distribution.
Claims25
A process for the manufacture of hollow ceramic microspheres, comprising:
- (a) forming an aqueous sol of a member selected from the group consisting of ceramic materials and materials calcinable to ceramic materials;
- (b) dispersing said aqueous sol in a first organic liquid that does not dissolve water from said aqueous sol, to form an emulsion with said aqueous sol as a disperse phase and with a continuous phase that does not extract water from said disperse phase;
- (c) adding said emulsion to a second organic liquid, said second organic liquid being one which dissolves water from said aqueous sol, to convert said emulsion to a suspension of hollow microspheres filled with a mixture of said second organic liquid and water;
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- (d) recovering and calcining said hollow microspheres to remove liquid therefrom and to convert said hollow microspheres to hollow shells of crystalline metal oxide.
Dependencies are inferred from the claim text.