Preparation and Characterization of Niobium Carbide and Carbonitride

Kim, Hak Soo; Bugli, G.; Djéga‐Mariadassou, Gérald

doi:10.1006/jssc.1998.7993

Cited by 40 publications

(27 citation statements)

References 27 publications

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“…Nb(CN) powder is generally produced under a nitrogen atmosphere by the reduction and carburization of Nb 2 O 5 in the presence of carbon . The conditions for Nb(CN) synthesis under nitrogen can be determined from the Nb 2 O 5 –NbO 2 –Nb(CN) phase domains.…”

Section: Resultsmentioning

confidence: 99%

“…The niobium carbonitride has been synthesized by various methods. These include the heat treatment under nitrogen of niobium carbide prepared from niobium and carbon, the carbothermal reduction of niobium oxide under nitrogen, and the self‐propagating combustion of a mixture of niobium and carbon under nitrogen, Among these methods, the carbothermal reduction of niobium oxide is also a common process for synthesizing niobium carbonitride because of its low cost.…”

Section: Introductionmentioning

confidence: 99%

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Stability Domains of NbC and Nb(CN) During Carbothermal Reduction of Niobium Oxide

Kwon

Kim

2014

J. Am. Ceram. Soc.

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The Gibbs free energies of formation of Nb(CO) and Nb(CN) were calculated using ab initio simulation. Phase stability diagrams of the Nb 2 O 5 -NbO 2 -Nb(CO)-NbC/Nb(CN) system were constructed with respect to carbon activity, oxygen pressure, and the characteristics of solution formation. The constructed diagrams suggest that Nb 2 O 5 can be reduced without the formation of NbO owing to the formation of an Nb(CO) solid solution phase. The Nb(CO) phase might not be formed under a high partial pressure of nitrogen. This study demonstrates the absences of NbO and Nb(CO) during, respectively, the syntheses of NbC and Nb(CN) from Nb 2 O 5 . The constructed stability diagrams could also represent the conditions for syntheses of niobium carbide or stoichiometric niobium carbonitride by the carbothermal reduction of Nb 2 O 5 under argon or nitrogen. †

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stability Domains of NbC and Nb(CN) During Carbothermal Reduction of Niobium Oxide

Kwon

Kim

2014

J. Am. Ceram. Soc.

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“…However, previous work has shown that niobium pentoxide can be carburized from niobium monocarbide at 1173 K in a flux of CH 4 -H 2 mixture, using static-bed reactors for small samples and under very well controlled conditions (Kim, 1999;Teixeira da Silva et al, 1996;Li et al, 1998;Souza et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Niobium carbide synthesis by solid-gas reaction using a rotating cylinder reactor

Fontes

Gomes

Oliveira

et al. 2004

Braz. J. Chem. Eng.

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-A rotating cylinder reactor was designed for the synthesis of niobium carbide powders at 1173 K. Niobium carbide, NbC, was prepared by carbothermal reduction starting from commercial niobium pentoxide powders. The reactor was heated using a custom-made, two-part, hinged, electric furnace with programmable temperature control. The design and operational details of the reactor are presented. The longitudinal temperature gradient inside the reactor was determined. Total reaction time was monitored by a gas chromatograph equipped with an FID detector for determination of methane concentrations. The results show that time of reaction depended on rotation speed. NbC was also prepared in a static-bed alumina reactor using the same conditions as in the previous case. The niobium carbide powders were characterized by X-ray diffraction and compared with commercially available products. Morphological, particle size distribution and surface area analyses were obtained using SEM, LDPS and BET, respectively. Therefore, the present study offers a significant technological contribution to the synthesis of NbC powders in a rotating cylinder reactor.

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“…The nanoparticles are the secondary particles, which are made of primary crystals. 15,16 The comparison of characteristics of C, TiC and NbC aerogels is listed in Table 1. The TEM image (Fig.…”

Section: Resultsmentioning

confidence: 99%

Low temperature pseudomorphic synthesis of nanocrystalline carbide aerogels for electrocatalysis

et al. 2015

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Here we demonstrate a low-temperature pseudomorphic transformation of carbide aerogels for electrocatalysis. The sustaining temperature-gradient-driving transportation of a volatile metal compound and carbon diffusion-limited growth yield highly active, mesoporous, nanocrystalline TiC and NbC aerogels with high surface areas (265 and 159 m 2 g À1 ) and porosities (83.37 and 79.36 vol%) from carbon aerogels, respectively. View Article Onlinea r b is measured by a weight method, average of 3 samples. b r s is obtained from helium pycnometry. c V total is calculated by the single-point adsorption method. d Porosity is calculated via P ¼ 1 À r b /r s . This journal is

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Preparation and Characterization of Niobium Carbide and Carbonitride

Cited by 40 publications

References 27 publications

Stability Domains of NbC and Nb(CN) During Carbothermal Reduction of Niobium Oxide

Stability Domains of NbC and Nb(CN) During Carbothermal Reduction of Niobium Oxide

Niobium carbide synthesis by solid-gas reaction using a rotating cylinder reactor

Low temperature pseudomorphic synthesis of nanocrystalline carbide aerogels for electrocatalysis

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