Translucent PCA ceramic, ceramic discharge vessel, and method of making
US7247591B2 · kind B2 · utility
5Cited by
9References
7Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | May 26, 2005 |
| Grant date | Jul 24, 2007 |
| Priority date | — |
| Expiry date | Aug 16, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B2235/94
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A translucent polycrystalline material suitable for use in ceramic discharge vessels for metal halide lamps is produced by sintering an alumina powder doped with a MgO sintering aid in a nitrogen atmosphere containing a partial pressure of a vapor phase carbon-containing species. The sintered polycrystalline alumina has a grain boundary phase containing aluminum, oxygen and nitrogen. The formation of the AL—O—N grain boundary phase is believed to facilitate the transport of nitrogen from entrapped pores during sintering. Preferably, the PCA is sintered in a carbon-element furnace under flowing ultra-high-purity nitrogen.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.