Process for the preparation of alkali-poor .alpha.-alumina for ceramic purposes
US4477427A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 9, 1982 |
| Grant date | Oct 16, 1984 |
| Priority date | — |
| Expiry date | Nov 9, 2002 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01F7/442
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Process for the preparation of alkali-poor .alpha.-alumina for ceramic purposes. Technical grade aluminum hydroxide is activated and calcinated in the presence of a mineralizing mixture comprising halides and boron compounds. The process further comprises activating aluminum hydroxide at a temperature of 500-600 degrees C., washing the activated product with alkali-free water containing calcium ions and having a conductivity not exceeding 70 .mu.S/cm until the alkali content expressed in Na.sub.2 O becomes lower than 0.15% by weight, adding 0.4-0.7% by weight of a mineralizing mixture to the washed product, and calcinating the same at a temperature of 1200-1350 degrees C.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.