Purification of tungsten hexafluoride
US5324498A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 1990 |
| Grant date | Jun 28, 1994 |
| Priority date | — |
| Expiry date | Mar 30, 2010 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01G41/04
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A process is provided for purifying liquid tungsten hexafluoride containing volatile and non-volatile impurities. The process comprises the steps of evaporating tungsten hexafluoride from non-volatile impurities dissolved in liquid tungsten hexafluoride and condensing the evaporated tungsten hexafluoride. The condensed tungsten hexafluoride is subjected to freezing to solidify the tungsten hexafluoride. Volatile impurities are then evacuated from the solid tungsten hexafluoride. Thereafter, the solid tungsten hexafluoride is thawed to liquid tungsten hexafluoride to release trapped volatile impurities and then heated to a temperature above the boiling point of tungsten hexafluoride under pressure in a closed container. The volatile impurities dissolved in the thawed tungsten hexafluoride are removed and collected above the thawed tungsten hexafluoride and vented into an evacuated space.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.