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U.S. Department of Energy
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Nonoxide ceramic powder synthesis

Conference · · Combustion and Flame; (United States)
OSTI ID:6806497
;  [1]
  1. Phillips Petroleum Co., Bartlesville, OK (United States)

SiC was synthesized by injecting mixtures of carrier gas plus a silicon compound (Si(CH[sub 3])[sub 4], SiCH[sub 4]) into hot burned gas downstream of a fuel rich hydrocarbon-oxygen flame. The gas temperature during ceramic synthesis was measured at 1,500--1,650 C. Reaction stoichiometry was investigated by changing the carrier gas injected with the silicon compound. Both experimental data and equilibrium calculations show that SiC is stable in mixtures of CO and H[sub 2] at synthesis temperature. However, CO[sub 2] addition to the synthesis zone causes silicon oxidation to SiO[sub 2] with little SiC formation. Flame stoichiometry shows the same influence: mixtures around a molar C/O = 1, where the burned gas is CO and H[sub 2], favor ceramic synthesis. Richer flames are cooler and produce excessive soot while leaner flames produce H[sub 2]O and CO[sub 2] which oxidize silicon species. Two key results give guidance about the ceramic formation mechanism: (1) In these experiments silicon species do not equilibrate with the gas species. (2) SiC forms from reaction of SiH[sub 4] + C[sub 2]H[sub 4], which shows silicon species both breaking and forming chemical bonds during the reaction process. This result opens the possibility of a gas phase kinetic mechanism for ceramic powder formation. In general, these experiments present a new combustion driven material synthesis route that may apply to a variety of compounds.

OSTI ID:
6806497
Report Number(s):
CONF-940711--
Journal Information:
Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 100:1-2; ISSN CBFMAO; ISSN 0010-2180
Country of Publication:
United States
Language:
English