US4291444A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of manufacturing a tungsten lamp filament
Assignee: General Electric Co
•
Filing: 1978-08-28
•
Granted: 1981-09-29
•
Expires: 1998-08-28
Abstract
Abstract An electric lamp filament of tungsten is disclosed that has been coiled and heat-treated to at least 1600° C. on a wire mandrel containing molybdenum but which is essentially free of molybdenum contamination. A barrier layer of tungsten or tantalum is provided on said mandrel to preclude the molybdenum contamination and the coated mandrel can thereafter be dissolved from the uncontaminated tungsten filament coil in an acid mixture.
Inventors
- 👤 Lewis V. McCarty
- 👤 John W. Pugh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:28
CPC Classifications
H; H01; H01K; H01K3/00; H01K3/02; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/4981; Y10T29/49812
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
78 words
An improved process of manufacturing a tungsten lamp filament which includes coiling and heat treating said filament to at least 1600° C. on a molybdenum wire mandrel until significant stress relaxation has taken place, wherein the improvement comprises coating the bare metal surface of said wire mandrel with a chemical vapor deposit of a refractory metal selected from tungsten and tantalum prior to said coiling and heat treating steps to thereby prevent molybdenum contamination of said tungsten filament.
Claim 2
Dependent Claim
78 words
An improved process of manufacturing a tungsten lamp filament which includes coiling and heat treating said filament to at least 1600° C. on a molybdenum wire mandrel until significant stress relaxation has taken place, wherein the improvement comprises coating the bare metal surface of said wire mandrel with a chemical vapor deposit of a refractory metal selected from tungsten and tantalum prior to said coiling and heat treating steps to thereby prevent molybdenum contamination of said tungsten filament.
Claim 3
Dependent Claim
13 words
An improved process as in claim 1 wherein the tungsten filament is recrystallized.
Claim 4
Dependent Claim
13 words
An improved process as in claim 1 wherein the tungsten filament is annealed.
Claim 5
Dependent Claim
16 words
An improved process as in claim 1 wherein the wire mandrel is molybdenum coated with tungsten.
Claim 6
Dependent Claim
16 words
An improved process as in claim 1 wherein the wire mandrel is molybdenum coated with tantalum.
References Cited (Backward Citations)
US2723926A
Cited
US3461921A
Cited
US3285293A
Cited
US3662789A
Cited
US3812393A
Cited
US3877495A
Cited
US3865074A
Cited
US4049024A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-28 | 1985-03-30 | 1985-09-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-28 | 1989-03-30 | 1989-09-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-28 | 1993-03-30 | 1993-09-29 | $7700.00 | Window Closed / Lapsed |