Hot pressed niobium carbide--graphite composites. Progress report

Technical Report · Thu Jun 01 00:00:00 EDT 1967

DOI:https://doi.org/10.2172/4406241· OSTI ID:4406241

Blay, J S

Declassfied 30 Aug 1973. An investigation was conducted to determine the manufacturability of hot-pressed 75--25 wt% NbC--graphite composites. Commercially available and custom ground superfine carbide and graphite powder combinations were evaluated; the hot pressing operation was studied; and machining techniques were developed. The relationship of the physical properties of the starting powders to thermal and mechanical properties of the composites was studied. Room temperature and 2400 deg C tensile, compressive, and flexural strengths were determined; tensile creep at 24OO deg C and compressive deformation (creep) at 2200 deg C were studied; and thermal expansion and specific heat to 5000 deg F were determined. In addition, the effect of a post hot-pressing heat treatment was studied. Evaluation of results shows that equally dense, high strength composites can be obtained by hot-pressing large or small billets. For the composition studied, the resulting structure of the superfine carbide graphite powders was a weak carbide continuous phase in a dominant continuous graphite phase. The resulting structure from commercially available carbide/graphite powders was a dominant carbide network. Optimum mechanical properties were obtained both at room temperature and at high temperature, using normal commercially available high purity powders. Thermal properties do not appear to be dependent on the physical properties of the powders. A post hot-pressing hightemperature heat treatment is important in improving the dimensional stability of the billets. Ultrasonic material removal techniques developed for rough machining and diamond tooling developed for final machining provided an economical high production method for manufacturing composite hardware. (auth)

• Research Organization: Westinghouse Electric Corp., Pittsburgh, PA (United States). Astronuclear Lab.
• Sponsoring Organization: USDOE
• DOE Contract Number: SUBNP-1
• NSA Number: NSA-29-003001
• OSTI ID: 4406241
• Report Number(s): WANL-TME-1630
• Resource Relation: Other Information: Declassified 30 Aug 1973. Orig. Receipt Date: 30-JUN-74
• Country of Publication: United States
• Language: English

Related Subjects

N50120* -Metals
Ceramics
& Other Materials-Ceramics & Cermets-Preparation & Fabrication
N77800 -Reactors-Space
Mobile
Propulsion
Transportation & Package Reactors
N79200 -Reactors-Reactor Components & Accessories
*COMPOSITE MATERIALS- MECHANICAL PROPERTIES
*GRAPHITE- FABRICATION
*NERVA REACTOR- REACTOR MATERIALS
*NIOBIUM CARBIDES- FABRICATION
FLEXURAL STRENGTH
HEAT TREATMENTS
HIGH TEMPERATURE
HOT PRESSING
MEDIUM TEMPERATURE
PHYSICAL PROPERTIES
POWDERS
SPECIFIC HEAT
TENSILE PROPERTIES
THERMAL EXPANSION
VERY HIGH TEMPERATURE
NESDPS Office of Nuclear Energy Space and Defense Power Systems