Process for manufacturing crystalline alumina
US4487756A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1983 |
| Grant date | Dec 11, 1984 |
| Priority date | — |
| Expiry date | Aug 12, 2003 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2004/54
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
The invention relates to a process for manufacturing crystalline alumina from aluminum hydroxide which after further conventional treatment is advantageously suitable for ceramic and refractory purposes or as a lapping and polishing agent. The process is such that aluminum hydroxide with a Na.sub.2 O content of .ltoreq.0.1 wt. % with respect to Al.sub.2 O.sub.3 is subjected either directly or after prior partial dehydration to a thermal treatment above the temperature for transformation to .alpha.--Al.sub.2 O.sub.3. The aluminum hydroxide has an addition of an ammonium containing mineralizer made to it, simultaneously in the presence of boron and/or fluorine, in particular an addition of NH.sub.4 BF.sub.4. The product is characterized by way of the essentially isometric shape of the single crystals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.