PROCESS FOR PRODUCING POLIDISPERS ALUMINIUME-OXIDES, WHICH CONTAINS SHALLER THAN 1 µM ONE-CRYSTALSIZE GRAINS

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 i...

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Bibliographische Detailangaben
Hauptverfasser:	REVESZ,LASZLO, LENGYEL,LASZLO, SCHLEGEL,MIKLOS, KAPTAY,GYOERGY, MATYASI,JOZSEF, CSIGA,LAJOS, TOTH,IMRE, NEMETH,SANDOR, TOTH BENJAMINNE,DR, T.TOTH,JOZSEF, OERI,ISTVAN, PIRIK,SANDOR
Format:	Patent
Sprache:	eng
Schlagworte:	AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUSPOLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE APPARATUS THEREFOR ARTIFICIAL STONE CEMENTS CERAMICS CHEMISTRY COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDINGMATERIALS COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM,CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THERARE-EARTH METALS CONCRETE CRYSTAL GROWTH INORGANIC CHEMISTRY LIME, MAGNESIA METALLURGY PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE REFINING BY ZONE-MELTING OF MATERIAL REFRACTORIES SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE SINGLE-CRYSTAL-GROWTH SLAG TREATMENT OF NATURAL STONE UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL ORUNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL
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Beschreibung
Zusammenfassung:	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.