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Low-carbon boron carbides produced by CVD (chemical vapor deposition)

Conference ·
OSTI ID:6512056
Boron carbides with low C contents were produced from BCl/sub 3/ and CCl/sub 4/ by chemical vapor deposition at temperatures of 1020 to 1500/sup 0/C. The deposits were found to be between B/sub 13/C/sub 2/ and B/sub 11/C (8.3 to 13.3 at. %C) in composition by means of Auger electron spectroscopy. Raman spectroscopy demonstrates that the specimens contain very little free carbon. Further, disordering of C in the chains and icosahedra of the rhombohedral boron carbide structure for C contents of less than 20 at. % is indicated by the Raman results. Single-phase rhombohedral boron carbides with C contents as low as 12.5 at. % (approx. =B/sub 7/C) have been produced. The most B-rich specimens, containing 8.3 at. % (B/sub 11/C) or less C, were phase separated. At least one of the phases in the phase separated specimens is tetragonal. The electrical conductivity and Hall mobility of the B/sub 11/C specimen are reported.
Research Organization:
Sandia National Labs., Albuquerque, NM (USA); Jet Propulsion Lab., Pasadena, CA (USA)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
6512056
Report Number(s):
SAND-86-2804C; CONF-870438-19; ON: DE87010684
Country of Publication:
United States
Language:
English