Method of manufacturing .alpha.-alumina
US4019914A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 24, 1974 |
| Grant date | Apr 26, 1977 |
| Priority date | — |
| Expiry date | Jun 24, 1994 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/10
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method of manufacturing .alpha.-alumina with a degree of purity of at least 98% which has a high sintering activity. The .alpha.-alumina contains at least 98% .alpha.-Al.sub.2 O.sub.3 and not more than 0.1% Na (calculated as Na.sub.2 O), and not more than 0.1% Ti (calculated as TiO.sub.2). The .alpha.-alumina also contains between 0.03% and 2% of Fe.sub.2 O.sub.3 and/or Cr.sub.2 O.sub.3. The .alpha.-alumina is formed by first fine grinding and then calcining, preferably at a temperature between about 1120.degree. C and 1350.degree. C, an aluminum hydroxide and/or hydrated aluminum oxide. The .alpha.-alumina is then cooled and finely ground to provide an .alpha.-alumina having excellent sintering activity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.