Alpha-alumina and method for producing same
US6162413A · kind A · utility
8Cited by
33References
4Claims
0Family size
Assignee
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Key dates
| Filing date | Sep 8, 1997 |
| Grant date | Dec 19, 2000 |
| Priority date | — |
| Expiry date | Sep 8, 2017 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/80
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A powdery .alpha.-alumina having an alumina purity of at least 99.8 wt. %, a sodium content of 40 ppm or less and an iron content of 20 ppm or less, which is obtained by grinding aluminum hydroxide which is produced by the Bayer process or a transition alumina which is obtained by precalcining aluminum hydroxide produced by the Bayer process, and calcining the aluminum hydroxide or transition alumina in an atmosphere containing 1 vol. % or more of a hydrogen chloride gas, or an atmosphere containing 1 vol. % or more of a chlorine gas and 0.1 vol. % or more of steam, at a temperature of 600 to 1400.degree. C.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.