Hollow alumina microspheres from boehmite sols

摘要

Hollow alumina microspheres were obtained from emulsified boehmite sols by an ion extraction method. The viscosity and the equivalent alumina content of the sols were found to affect the characteristics of the derived microspheres. High-viscosity sols produced broken microspheres. A temperature of about 400-500 degrees C for boehmite to gamma-Al2O3 transformation in the gel microspheres was observed by differential thermal analysis and X-ray diffraction. Complete crystallization of the gel microspheres to alpha-Al2O3 occurred at 1200 degrees C. A tentative mechanism for the formation of the hollow microspheres is presented. (C) 1998 Kluwer Academic Publishers. [References: 23]