Preparation of sintered alpha alumina having microcrystalline structure

摘要

Preparation of sintered bodies of alpha alumina having microcrystalline structure. A hydrolysable, complexed, aluminium compound is subjected to hydrolytic condensation in a known manner to give a nano-dispersed sol. having a particle size of below 100 nm; or a metastable, aluminium-oxygen compound which is convertible to alumina is converted into a nano-dispersed sol. with a particle size of below 100 nm by a known manner; or the products of the two processes are mixed together; the products of these three processes are mixed with known alpha-alumina sinterable powders with a particle size of above 100 nm in a weight ratio of 99:1 to 1:99; the product is optically converted into a gel using a known method and shaped into a body; and the product is dried, calcined and sintered in the usual way but without the use of seed crystals. Also claims sintered alpha.alumina bodies with microcrystalline structure produced by the process; and the use of the bodies as grinding or polishing powder or material.