US4302250A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Glass envelopes for tungsten-halogen lamps
Assignee: Corning Glass Works
•
Filing: 1980-09-08
•
Granted: 1981-11-24
•
Expires: 2000-09-08
Abstract
Abstract The instant invention is concerned with glass envelopes for tungsten-halogen lamps. The glasses exhibit a strain point higher than 750° C., a coefficient of thermal expansion (0°-300° C.) between 42-44×10 -7 /°C., a liquidus temperature below 1300° C., a viscosity at the liquidus of at least 40,000 poises, and consist essentially, in weight percent on the oxide basis, of 64-68% SiO 2 , 11-14% CaO, 16.5-18.5% Al 2 O 3 , and 2-6.5% SrO+BaO consisting of 0-4% SrO and 0-5% BaO. The preferred glasses demonstrate a viscosity of less than 1000 poises at temperatures no higher than 1520° C. and contain at least 3% total of SrO+BaO, those components being present in a molar ratio SrO:BaO ranging from 2:1-1:2.
Inventors
- 👤 Paul S. Danielson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:03
CPC Classifications
C; C03; C03C; C03C3/00; C03C3/04; C03C3/076; C03C3/083; C03C3/085; C03C3/087
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
119 words
A glass composition suitable as an envelope for a tungsten-halogen lamp and for sealing to molybdenum metal, said glass exhibiting a strain point higher than 750° C., a coefficient of thermal expansion (0°-300° C.) between 42-44×10 31 7 /°C., a liquidus temperature below 1300° C., a viscosity at the liquidus of at least 40,000 poises, a viscosity of less than 1000 poises at temperatures no higher than 1520° C., and consisting essentially, expressed in terms of weight percent on the oxide basis, of 64-68% SiO 2 , 11-14% CaO, 16.5-18.5% Al 2 O 3 , and 3-6.5% SrO+BaO, consisting of 0-4% SrO and 0-5% BaO, those latter two components being present in a molar ratio SrO:BaO ranging from 2:1-1:2.
Claim 2
Dependent Claim
119 words
A glass composition suitable as an envelope for a tungsten-halogen lamp and for sealing to molybdenum metal, said glass exhibiting a strain point higher than 750° C., a coefficient of thermal expansion (0°-300° C.) between 42-44×10 31 7 /°C., a liquidus temperature below 1300° C., a viscosity at the liquidus of at least 40,000 poises, a viscosity of less than 1000 poises at temperatures no higher than 1520° C., and consisting essentially, expressed in terms of weight percent on the oxide basis, of 64-68% SiO 2 , 11-14% CaO, 16.5-18.5% Al 2 O 3 , and 3-6.5% SrO+BaO, consisting of 0-4% SrO and 0-5% BaO, those latter two components being present in a molar ratio SrO:BaO ranging from 2:1-1:2.
Claim 3
Dependent Claim
26 words
A glass according to claim 1 having the approximate composition: SiO 2 : 65.80 Al 2 O 3 : 17.30 CaO: 12.95 SrO: 1.60 BaO: 2.35
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-23 | 1985-05-25 | 1985-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-23 | 1989-05-25 | 1989-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-23 | 1993-05-25 | 1993-11-24 | $7700.00 | Window Closed / Lapsed |