Process for surface conversion of vitreous silica to cristobalite
US4429009A · kind A · utility
11Cited by
7References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 30, 1981 |
| Grant date | Jan 31, 1984 |
| Priority date | — |
| Expiry date | Oct 30, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/315
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The specification discloses a process for converting the surface layer of a body of vitreous silica to the more stable crystalline form of silica known as cristobalite. The surface of the body of vitreous silica is exposed to a gas phase reactive atmosphere comprising atomic iodine at a predetermined elevated temperature for a predetermined period of time to convert the surface layer of the vitreous silica to polycrystalline cristobalite and thus passivate and enhance the stability of the treated surface. The disclosed process is particularly useful for forming improved crucibles, such as those used in crystal growth from a melt.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.