Development and characterization of carbon-bonded carbon fiber insulation for radioisotope space power systems
The General-Purpose Heat Source (GPHS), an improved radioisotope heat source, employs a unique thermal insulation material, carbon-bonded carbon fiber (CBCF), to protect the fuel capsule and to help achieve the highest possible specific power. The CBCF insulation is made from chopped rayon fiber about 10 ..mu..m in diameter and 250 ..mu..m long, which is carbonized and bonded with phenolic resin particles. The CBCF shapes, both tubes and plates, are formed in a multiple molding facility by vacuum molding a water slurry of the carbonized chopped-rayon fiber (54 wt %) and phenolic resin (46 wt %). The molded shapes are subsequently dried and cured. Final carbonization of the resin is at 1600/sup 0/C. Machining to close tolerances (+-0.08 mm) is accomplished by conventional tooling and fixturing. The resulting material is an excellent lightweight insulation with a nominal density of 0.2 Mg/m/sup 3/ and a thermal conductivity of 0.24 W(m.K) in vacuum at 2000/sup 0/C. Several attributes that make CBCF superior to other known high-temperature insulation materials for the GPHS application have been identified. It has the excellent attributes of light weight, low thermal conductivity, chemical compatibility, and high-temperature capabilities. The mechanical strength of CBCF insulation is satisfactory for the GPHS application; it has passed vibration tests simulating launch conditions. The basic fabrication technique was refined to eliminate undesirable large pores and cracks often present in materials fabricated by earlier techniques. Also, processing was scaled up to incease the fabrication rate by a factor of 10. The specific properties of the CBCF were tailored by adjusting material and processing variables to obtain the desired results. We report here how work on CBCF characterization and development conducted at ORNL from 1978 through 1980 has contributed to the GPHS program to meet the requirements of both the Galileo and Ulysees Missions.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5567894
- Report Number(s):
- ORNL/TM-9381; ON: DE85013365
- Country of Publication:
- United States
- Language:
- English
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Carbon-bonded carbon fiber insulation for radioisotope space power systems
EVALUATION OF ALTERNATIVE FIBERS TO REPLACE NARC-RAYON FOR THE PRODUCTION OF CBCF
Related Subjects
07 ISOTOPES AND RADIATION SOURCES
RADIOISOTOPE HEAT SOURCES
THERMAL INSULATION
PRODUCTION
CARBON
DEGASSING
DENSITY
FIBERS
MECHANICAL PROPERTIES
THERMAL CONDUCTIVITY
ELEMENTS
HEAT SOURCES
NONMETALS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
360300* - Composite Materials- (-1987)
070300 - Isotopic Power Supplies