MONOHYDROXY ALUMINUM-OXIDE (BOEHMITE, ALOOH) AS A REACTIVE BINDER FOREXTRUSION OF ALUMINA CERAMICS

Monohydroxy aluminium oxide (Boehmite, AlOOH) has been used as an extr usion aid along with alpha-alumina and gamma-alumina particulates. Ext ended ball milling of the mixture using alumina grinding media imparts nucleating seeds to boehmite for an early conversion to alpha-alumina . The boehmite-gamma-alumina mixture appears to result in a denser alu mina ceramic accompanied by an enhanced grain growth indicating the hi gher reactivity at higher temperatures compared to the boehmite-alpha- alumina system. The reason for this novel behaviour is probably the co ating of nanosize boehmite containing nucleating sites on the porous g amma-alumina powders resulting in enhanced diffusion reactions. The pr esent study therefore provides scope for low temperature alumina ceram ics using boehmite binder along with partly dehydroxylated aluminum hy droxides. (C) 1997 Elsevier Science Limited.