Envelopes for tungsten-halogen lamps
AssigneeCorning Glass Works
InventorWilliam H. Dumbaugh, Jr.
Life of this patent
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Abstract
The present invention is directed to glasses especially suitable as envelopes for tungsten-halogen lamps. The glasses exhibit strain points of at least about 670.degree. C., a coefficient of thermal expansion (0.degree.-300.degree. C.) of 42-45.times.10.sup.-7 /.degree.C. and can be readily melted and shaped utilizing conventional glass melting and high speed tube drawing processes. The glasses consist essentially, in weight percent, of ______________________________________ SiO.sub.2 60.0 .+-. 1.5 Al.sub.2 O.sub.3 17.0 .+-. 1.0 B.sub.2 O.sub.3 5.0 .+-. 0.8 CaO 11.4 .+-. 0.8 MgO 7.5 .+-. 0.8 ______________________________________
Claims2
A glass envelope for a tungsten-halogen incandescent lamp, said glass exhibiting a strain point of at least 670.degree. C., a coefficient of thermal expansion (0.degree.-300.degree. C.) of 42-45.times.10.sup.-7 /.degree.C., a liquidus temperature below 1150.degree. C., and a viscosity at the liquidus temperature greater than 2.times.10.sup.4 poises, and consisting essentially, expressed in weight percent on the oxide basis, of
- ______________________________________ SiO.sub.2 60.0 .+-. 1.5 Al.sub.2 O.sub.3 17.0 .+-. 1.0 B.sub.2 O.sub.3 5.0 .+-. 0.8 CaO 11.4 .+-. 0.8 MgO 7.5 .+-. 0.8 ______________________________________
- the total Al.sub.2 O.sub.3 +SiO.sub.2 being held between 74.5-78, the weight ratio SiO.sub.2 :Al.sub.2 O.sub.3 being held between about 3.3-3.8, and the weight ratio CaO:MgO being held between about 1.3-1.8.
Dependencies are inferred from the claim text.