AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Low-Temperature Hydrolysis of AlCl3 Vapor in an Aerosol Reactor to Produce Spherical Preforms for Ceramic-Grade Alumina
HOEY KYUNG PARK, Kyun Young Park, Kyeong Youl Jung, Kongju National University, South Korea
Abstract Number: 60 Working Group: Nanoparticles and Materials Synthesis
Abstract Fumed alumina has been commercially produced by hydrolysis and oxidation of AlCl$_3 vapor in a flame as high as 1800 degrees C, and used as reinforcing fillers and abrasives. The fumed alumina is highly agglomerated and too low in bulk density to be used for ceramics. In the present study, AlCl$_3 vapor was hydrolyzed in an aerosol reactor at a lower temperature of 300 - 500$^oC to produce spherical preforms, AlO$_xCl$_y(OH)$_z, for ceramic-grade alumina. The reactor is tubular, 2.4 cm in diameter and 30 cm in length, and electrically heated. The solid AlCl$_3 was evaporated continuously with a LabVIEW programmed controller and mixed with water vapor in nitrogen. Investigated on the morphology and size of the preforms were the effects of the reaction temperature, the H$_2O to AlCl$_3 molar ratio, the AlCl$_3 concentration, and the axial position of mixing AlCl$_3 vapor with H$_2O vapor. The obtained preforms were spherical, loosely agglomerated, and distributed in the size range of 50 to 200 nm. The chlorine content was 0.34 to 0.43 at%. The preforms were calcined at 1200$^oC to obtain an α-alumina nearly 100 % in α-transformation degree and free of chlorine. The weight loss upon calcination was 35 to 45 %. The surface area equivalent diameter of the calcined particles was about 100 nm. We have demonstrated the preparation of ~ 100 nm α-alumina particles for potential application in functional ceramics, using the new preforms derived from AlCl$_3 through an aerosol route.