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Rapid carbothermal reduction of boron oxide in a graphite transport reactor
Author(s) -
Weimer Alan W.,
Roach Raymond P.,
Haney Christopher N.,
Moore William G.,
Rafaniello William
Publication year - 1991
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690370513
Subject(s) - carbothermic reaction , boron oxide , materials science , boron , boron carbide , nucleation , graphite , chemical engineering , precipitation , pyrolysis , oxide , carbide , metallurgy , chemistry , organic chemistry , physics , meteorology , engineering
Uniform submicron crystals of B 4 C, boron‐enriched boron carbide, and B 4 C/TiB 2 composite powders have been synthesized continuously by rapid carbothermal reduction at approximately 2,200 K in a 0.14 m ID × 1.68 m long pilot‐scale graphite transport reactor. A unique reactor design allowed for continuous feeding of a meltable boron oxide containing precursor, rapid heating rates that completed the carbothermal reduction reaction in seconds, and an expanded cooling that allowed for the precipitation in space of volatile excess boron oxides. Powder morphology resembled that of powder synthesized by laser pyrolysis of gaseous reactants. Rapid heating rates and minimized reaction times at high temperatures promoted nucleation with limited crystal growth. Dense parts fabricated from these powders had fine grains and extreme hardness.