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Properties of Cast Columbium Carbide-carbon Alloys.

Asai-G; Paulson-DL; Kelly-HJ
NTIS: PB 198 283 :68 pages
Properties obtained for columbium carbide-carbon castings were compared with those of hot-pressed composites of similar composition. The properties were oxidation resistance in static air between 500 deg and 700 deg c, linear thermal expansion between 20 deg and 2,400 deg c, electrical resistivity between 20 deg and 1,500 deg c, microhardness between 20 deg and 1,500 deg c, and modulus of rupture between 1,300 deg and 1,800 deg c. Cbc-c castings differed markedly from hot-pressed material with respect to microstructure, electrical resistivity, and modulus of rupture, but behaved quite similarly with respect to oxidation resistance, thermal expansion, and hot hardness. In oxidation resistance, thermal expansion, and hot hardness both materials were independent of carbon content. Both castings and hot-pressed composites oxidize rapidly in air above 600 deg c, have thermal expansion coefficients very similar to columbium metal, and the logarithm of the hardness decreases linearly with increasing temperature. The higher electrical resistivity of hypereutectic castings over hypereutectic hot pressings was attributed to the presence of highly oriented graphite needles in the castings. The modulus of rupture of castings was 1- 1/2 to 2 times that of hot-pressed composites. Both materials displayed bend ductility above 1,800 deg c.
Publication Date
Document Type
IH; Report of Investigation;
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
RI 7479
NIOSH Division
Source Name
NTIS: PB 198 283