The role of iridium in the work-function behavior of dilute-solution tungsten, iridium alloys

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:7267009

D'Cruz, L A

Requirements of thermionic electrode materials have emphasized the need for substantial improvements in microstructural stability, strength and creep resistance at service temperatures in excess of 2,500K. This study utilized both chemical alloying and mechanical alloying procedures for the addition of iridium to submicron W powder followed by cold compaction and sintering. The shrinkage characteristics and microstructural development were studied in iridium-added tungsten compacts with a range of additive levels. An electron-emission study was subsequently carried out in order to evaluate the work-function behavior of the consolidated alloys. The work function was obtained from current-emission measurements from the electrode surface under UHV conditions in the temperature range of 1,800 to 2,500K using a Vacuum Emission Vehicle (VEV). The data show that the magnitude of the work function in these alloys varied with temperature and was sensitive to sub-surface iridium content.

• Research Organization: Arizona State Univ., Tempe, AZ (United States)
• OSTI ID: 7267009
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
300403 -- Thermionic Converters-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
DIRECT ENERGY CONVERTERS
ELECTRODES
ELEMENTS
FUNCTIONS
IRIDIUM
IRIDIUM ALLOYS
METALS
NESDPS Office of Nuclear Energy Space and Defense Power Systems
PLATINUM METAL ALLOYS
PLATINUM METALS
QUANTITY RATIO
THERMIONIC CONVERTERS
TRANSITION ELEMENTS
TUNGSTEN ALLOYS
WORK FUNCTIONS