Future space applications such as outer planetary orbiters, lunar and planetary bases, high capacity communications and space based manufacturing demand high power units such as Thermionic Energy Converters (TEC) for their efficient operation. In such applications, higher temperatures translate into higher power levels at lower weight and in order to have energy conversion at higher temperatures, it is necessary to develop refractory alloys with excellent thermal, thermionic and mechanical properties. The elevated temperature softening and recrystallization characteristics of sintered samples of thoriated (1 Mol.% ThO2) tungsten (W), rhenium (Re) alloys were the principal areas of investigation in the current research activity. Five alloys of W with 0 at.% Re, 3 at.% Re, 10 at.% Re, 25 at.% Re and 30 at.% Re, each compounded with 1 Mol.% ThO2 were subjected to vacuum annealing in the temperature range of 1400 K to 2500 K in order to obtain their one-hour recrystallization temperatures along with their grain growth characteristics. It was found that the addition of 1 Mol.% ThO2 actually raised the recrystallization temperature of sintered W to 1810 K and that of the W, 25 at.% Re alloy to 2100 K. The alloys were found to have coarse as well as fine ThO2 particles distributed in them, the consequence of which was a wide variation in microhardness values.
Thermionic emitter material characteristics at elevated temperatures
Eigenschaften von Emitterwerkstoffen bei der thermionischen Energieumwandlung bei erhoehten Temperaturen
1987
6 Seiten, 21 Bilder, 2 Tabellen, 12 Quellen
Aufsatz (Konferenz)
Englisch
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