Monolithic seal for a sapphire metal halide lamp
US6955579B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 19, 2004 |
| Grant date | Oct 18, 2005 |
| Priority date | — |
| Expiry date | Mar 30, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J61/363
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method of producing a ceramic metal halide discharge lamp having a monolithic seal between a sapphire (single crystal alumina) arc tube and a polycrystalline alumina (PCA) end cap. The method includes the steps of providing an arc tube of fully dense sapphire and providing an end cap made of unsintered compressed polycrystalline alumina powder doped with magnesium oxide and yttrium oxide. The end cap is heated until it is presintered to remove organic binder material at a low temperature relative to the sintering temperature. The presintered end cap is placed on an end portion of the arc tube to form a close interface between the two. The presintered end cap and adjacent arc tube are then heated to until the end cap is fully sintered onto the arc tube and the sapphire tube grows into the end cap. A monolithic seal is formed along the interface between the end cap and the arc tube as the sapphire tube grows into the polycrystalline alumina end cap. The yttrium oxide promotes increased growth between sapphire tube and the PCA end cap and is not detrimental to the metal halide chemistry, nor subject to erosion by the metal halide chemistry.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.