Compositions: ceramic – Ceramic compositions – Aluminum compound containing
Reexamination Certificate
2007-07-24
2007-07-24
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Aluminum compound containing
C501S096100, C501S098400, C313S636000
Reexamination Certificate
active
10908795
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.
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Clark Robert F.
Group Karl
Osram Sylvania Inc.
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