SYNTHESIS OF NIOBIUM CARBIDE FROM AMMONIUM NIOBIUM(V) OXALATE PRECURSOR AT LOW TEMPERATURE IN ROTATING CYLINDER REACTOR

摘要

The reaction of oxalic precursor {(NH{sub}4)3[NbO(C{sub}2O{sub}4){sub}3]H{sub}2O}, was prepared from the Nb{sub}2O{sub}5, to niobium carbide (NbC) were performed in a rotating cylinder reactor scale-lab designed to niobium carbide powders synthesis at low temperature (1173 K). The NbC was prepared by a oxalic precursor and as well of commercial niobium pentoxide under flowing CH{sub}4 -H{sub}2 mixtures. The reactor was heated through a bi-partied electric furnace with programmable temperature. The reaction overall time was determined from the curve of methane absorption evolution by gas chromatograph (FID) analysis. The preliminary results showed that the conversion function depends on the rotation, temperature, mixture flow, CH{sub}4/H{sub}2 ratio and heating rate. The niobium carbide was characterized through X-ray diffraction and compared to the commercial products. The reaction of oxalic precursor {(NH{sub}4)3[NbO(C{sub}2O{sub}4){sub}3]H{sub}2O} to niobium carbide (NbC) in 3% (v/v) CH{sub}4/H{sub}2 yielded smallest grain size as well smaller overall time when compared with obtained direct by commercial Nb{sub}2O{sub}5, however it had small mass conversion due the solid carryover not controlled.