Process for preparing aluminium oxide having a single crystal size below 1 mu m

摘要

The invention relates to a process for preparing aluminium oxide having a single crystal (crystallite) size below 1 mu m or polydisperse aluminium oxide containing such an aluminium oxide fraction. According to the invention, the procedure is to heat treat a hydrated aluminium oxide, preferably an industrial alumina hydrate prepared by the Bayer process, at a temperature of 500-800@C until at least 85 % of its original insoluble sodium content can be washed out by water, then to heat treat it in aqueous suspension for 0.1-3 hours at 100-350@C under pressure and, optionally after addition of a mineraliser to calcine it at 1100-1400@C. This gives a product having a single crystal size below 1 mu m which can be used, in particular, for ceramic and oxide ceramic purposes.