METHOD OF MAKING TUNGSTEN FILAMENTS
Abstract
A method of making tungsten filaments is described in which the tungsten is completely free of isotope impurities in the range of masses 234 to 245 for use in mass spectrometers. The filament comprises a tantalum core generally less than 1 mil in diameter having a coating of potassium-free tantalum-diffused tungsten molecularly bonded thereto. In the preferred process of manufacture a short, thin tantalum filament is first mounted between terminal posts mounted in insulated relation through a backing plate. The tungsten is most conveniently vapor plated onto the tantalum by a tungsten carbonyl vapor decomposition method having a critical step because of the tendency of the tantalum to volatilize at the temperature of operntion of the filament. The preferred recipe comprises volatilizing tantalum by resistance henting until the current drops by about 40%, cutting the voltage back to build up the tungsten, and then gradually building the temperature back up to balance the rate of tungsten deposition with the rate of tantalum volatilization. (AEC)
- Inventors:
- Issue Date:
- OSTI Identifier:
- 4736408
- Patent Number(s):
- 3069584
- Assignee:
- U.S. Atomic Energy Commission
- Patent Classifications (CPCs):
-
C - CHEMISTRY C23 - COATING METALLIC MATERIAL C23C - COATING METALLIC MATERIAL
H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01K - ELECTRIC INCANDESCENT LAMPS
- NSA Number:
- NSA-17-008570
- Resource Type:
- Patent
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
- Subject:
- INSTRUMENTS AND INSTRUMENTATION; CARBONYLS; CATHODES; CURRENTS; DIFFUSION; HEATING; IMPURITIES; ISOTOPES; MASS SPECTROMETERS; PLATES; POTASSIUM; PRODUCTION; TANTALUM; TEMPERATURE; TUNGSTEN; TUNGSTEN COMPOUNDS; VAPORS; VOLATILITY; WIRES
Citation Formats
Frazer, J W. METHOD OF MAKING TUNGSTEN FILAMENTS. United States: N. p., 1962.
Web.
Frazer, J W. METHOD OF MAKING TUNGSTEN FILAMENTS. United States.
Frazer, J W. Tue .
"METHOD OF MAKING TUNGSTEN FILAMENTS". United States.
@article{osti_4736408,
title = {METHOD OF MAKING TUNGSTEN FILAMENTS},
author = {Frazer, J W},
abstractNote = {A method of making tungsten filaments is described in which the tungsten is completely free of isotope impurities in the range of masses 234 to 245 for use in mass spectrometers. The filament comprises a tantalum core generally less than 1 mil in diameter having a coating of potassium-free tantalum-diffused tungsten molecularly bonded thereto. In the preferred process of manufacture a short, thin tantalum filament is first mounted between terminal posts mounted in insulated relation through a backing plate. The tungsten is most conveniently vapor plated onto the tantalum by a tungsten carbonyl vapor decomposition method having a critical step because of the tendency of the tantalum to volatilize at the temperature of operntion of the filament. The preferred recipe comprises volatilizing tantalum by resistance henting until the current drops by about 40%, cutting the voltage back to build up the tungsten, and then gradually building the temperature back up to balance the rate of tungsten deposition with the rate of tantalum volatilization. (AEC)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1962},
month = {12}
}