INVESTIGATIONS OF CARBIDES AS CATHODES FOR THERMIONIC SPACE REACTORS. Quarterly Progress Report for the Period Ending May 31, 1963

Technical Report · Wed Sep 25 00:00:00 EDT 1963

DOI:https://doi.org/10.2172/4630177· OSTI ID:4630177

Two long-term test cells were fabricated and tested. One was loaded with a 30 UC--70 ZrC sample and the other with a 90 UC--10 ZrC samrple. The rates of vaporization of these samaples in vacuum were determined both in the absence and in the presence of a Ni anode maintained at 983 deg K with an electrode spacirig of 20 mils, hr order to set the baseline values. Measurement of the rates of vaporization of these samples under these conditions in the presence of Cs vapor at a pressure of about 1.8 torr are in preparation and will be continued for 1000 hr. Operation of the first test cell, containing the 90 UC- -10 ZrC emitter, was terminated after 510 hr because of leakage through a faulty metal gasket sealing the electron-gun compartment. The second test cell, containing a vapor-deposited W-clad UC emitter, was assembled and operated for a period of 111 hr. The test was terminated because a leak developed between the cell compartment and the electron-gun compartment. A control cell containing a solid W emitter is being assembled to check the modifications made in the design of the electron-gun channber and the filament in order to overcome such difficulties. Components for four other test cells were received. Fabrication of the emitters for these cells was partially completed. Measurements were completed on the vacuum vaporization rates of two cold-pressed and sintered 30 UC- 70 ZrC samples (B/sub 1/-9 and B/sub 1/-9a) at 2073 to 2273 deg K, and of a cold- pressed and sintered 90 UC--10 ZrC sample (B/sub 1-10)/ at 20l3 to 2085 deg K. The vacuuma emission of B/sub 1/-9 at 1700 to 2000 deg K and its open-pore fraction were also determined. The results are compared with those obtained on other UC-- ZrC samples. Physical redeposition studies were made in cases such as UC (2015 to 2083 deg K) with Ni anode at 558 to 983 deg K, 90 UC--10 ZrC (2027 to 2038 deg K) with Ni anode at 983 deg K, and 30 UC--70 ZrC (2082 to 2123 deg K) with Ni anode at 983 deg K. The activation, poisoning, and regeneration of the vacuum emission of a hyperstoichiometric UC sample were studied at 1670 to 2000 deg K. The hightemperature furnace, with the sample loading and testing fixtures in position, was tested at 2073 deg K. Minor mechani-cal difficulties encountered were corrected. The bearing guiding the loading rod was shifted to a cooler region of the furnace to avoid freezing of the rod by the bearing when the furnace is at a high temperature. The vacuum emmission of the stoichiometric UMoC/sub 2/ sample (D/sub 1/-2) was measured at 1750 to 2000 deg K. The rate of vacuum vaporization of a cold-pressed and sintered 30 UC--70 NbC sample (D/sub 1/- 3) was determined at 2050 to 2198 deg K. The compatibility between 98 wt% W--2 wt% Mo alloy and UCZrC (90 UC--10 ZrC and 30 UC--70 ZrC) was studied at 2073 deg K for a period of 24 hr (Run D/sub 2/-4). The diffusion samples after Runs D/sub 2/-1 (Ir, Re, and W-26Re versus UC), D/sub 2/-2 (85 wt-% W--15 wt-% Mo versus UC), and D/sub 2/-3 (98 wt-% W--2 wt-% Mo versus UC) were examined by electron- microprobe techniques. Electron-microprobe studies were made on the vapor- deposited W-clad hyperstoichiometric UC (5.02 wt% C, sample D/sub 3/-1) after it was subjected to diffusion-emission studies at 2073 deg K for a period of 838 hr. Two carbide samaples, one hypostoichiomaetric UC (4.70 wt% C/sub 3/ D/sub 3/-2) and the other 30 UC--70 ZrC (sample D/sub 3/-3) were clad with vapordeposited W and will be subjected to similar studies. (auth)

• Research Organization: John Jay Hopkins Lab. for Pure and Applied Science. General Atomic Div., General Dynamics Corp., San Diego, Calif.
• DOE Contract Number: NAS 3-2532
• NSA Number: NSA-17-041338
• OSTI ID: 4630177
• Report Number(s): GA-4391
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-63
• Country of Publication: United States
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
ACTIVATION
ANODES
BEARINGS
CARBIDES
CATHODES
CESIUM
COLD WORKING
COMPACTING
CONTROL
ELECTRODES
ELECTRON BEAMS
ELECTRON MICROSCOPY
ELECTRON PROBES
EMISSION
EVAPORATION
FABRICATION
FURNACES
HIGH TEMPERATURE
INTERMETALLIC COMPOUNDS
IRIDIUM ALLOYS
JOINTS
LEAKS
MATERIALS TESTING
MEASURED VALUES
MOLYBDENUM ALLOYS
NICKEL
NIOBIUM CARBIDES
POISONING
PRESSURE
REACTOR FUELING
REACTORS
REPROCESSING
RHENIUM ALLOYS
RODS
SINTERING
SPACE
TEMPERATURE
THERMIONICS
TUNGSTEN
TUNGSTEN ALLOYS
URANIUM ALLOYS
URANIUM CARBIDES
VACUUM
VAPORS
VELOCITY
ZIRCONIUM CARBIDES
NESDPS Office of Nuclear Energy Space and Defense Power Systems