Method of treating a ceramic discharge vessel
View Patent ↗The present invention is a ceramic discharge vessel for use in high-intensity-discharge (HID) lamps. The discharge vessel has a ceramic body and at least one seal region comprised of an aluminum oxynitride material. The seal region further has a surface layer for contacting a frit material wherein the surface layer is less reactive than the aluminum oxynitride material with respect to the molten frit during sealing. Preferably, the surface layer has a lower nitrogen content than the aluminum oxynitride material. The less reactive surface acts to minimize the formation of bubbles in the sealing frit during the sealing operation.
1. A method of treating a ceramic discharge vessel, comprising:
(a) providing a ceramic discharge vessel having a ceramic body, the ceramic body having at least one seal region, the seal region being comprised of an aluminum oxynitride material; and
(b) heating the seal region in a reducing atmosphere to form a surface layer having a lower nitrogen content than the aluminum oxynitride, the surface layer being disposed in the seal region so that it contacts a frit material that forms a seal in the seal region when the discharge vessel is sealed, and the surface layer being less reactive to the frit material during sealing than the aluminum oxynitride.
2. The method of claim 1 wherein the reducing atmosphere contains a N 2 -8% H 2 gas mixture.
3. The method of claim 2 wherein the seal region is heated to a temperature in a range from about 1400° C. to about 1700° C.
4. The method of claim 3 wherein the seal region is heated for about 1 to about 10 minutes.
5. The method of claim 1 wherein the frit material is comprised of Dy 2 O 3 , Al 2 O 3 and SiO 2 .