Investigation of sintered tungsten rhenium additive alloys for high temperature space application
In the quest to obtain enhanced bare work functions and increase their utility for thermionic energy conversion in future space applications, four tungsten rhenium alloys (W-3%Re, W-10%Re, W-25%Re, W-30%Re) were tested and found to have effective work functions of 4.87 +/- 0.04 eV, 4.80 +/- 0.04 eV, 4.94 +/- 0.04 eV, and 5.04 +/- 0.04 eV, respectively at an operating temperature of 1950 K. Tests were conducted at progressively increasing temperatures up to 2350 K and the effective work functions were found to increase uniformly with temperature. The effect of adding 1% ThO/sub 2/, to each one of the above mentioned alloys was to marginally increase the work functions to 4.83 +/- 0.04 eV, 4.82 +/- 0.04 eV, 4.96 +/- 0.04 eV and 5.06 +/- 0.04 eV, respectively. The work functions exhibited trends similar to that of the W, Re alloys, with increase in temperature and rhenium content. Normal spectral emissivities of W, W-3%Re, W-25%Re and W-30%Re were evaluated with a sophisticated photon-counting pyrometer. At 1400 K these alloys were found to have emissivities of 0.599, 0.521, 0.476, and 0.610, respectively, and in each case the values decreased with increase in operating temperature. W, 25%Re had the lowest and most stable values in the range of temperatures (1400 K to 2500 K) tested. The thoriated samples exhibited the same behavior as the W, Re samples but were observed to be more stable.
- Research Organization:
- Arizona State Univ., Tempe (USA)
- OSTI ID:
- 5429009
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
300403 -- Thermionic Converters-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
360104* -- Metals & Alloys-- Physical Properties
ACTINIDE COMPOUNDS
ALLOYS
CHALCOGENIDES
DIRECT ENERGY CONVERTERS
ELECTRODES
EMISSIVITY
FUNCTIONS
MECHANICAL PROPERTIES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RHENIUM ALLOYS
SURFACE PROPERTIES
THERMIONIC CONVERTERS
THORIUM COMPOUNDS
THORIUM OXIDES
TUNGSTEN ALLOYS
VERY HIGH TEMPERATURE
WORK FUNCTIONS