Formation of aluminium carbide by carbothermal reduction of alumina: Role of the gaseous aluminium phase

Lefort, Pierre; Tétard, D.; Tristant, Pascal

doi:10.1016/0955-2219(93)90132-b

Cited by 40 publications

(20 citation statements)

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“…This is perhaps unsurprising as the requirement of an inert environment is also essential for synthesis of Al4C3 via conventional heating processes. 40,41 The reasons for the preferential formation of oxides and oxycarbides under such conditions can perhaps be explained by the reaction processes that may occur in the presence of oxygen (Table 3). [40][41][42] The extremely high enthalpy and Gibbs free energy values for the oxide and oxycarbide phases strongly support the observed requirement for an oxygen-free environment.…”

Section: -41mentioning

confidence: 99%

“…40,41 The reasons for the preferential formation of oxides and oxycarbides under such conditions can perhaps be explained by the reaction processes that may occur in the presence of oxygen (Table 3). [40][41][42] The extremely high enthalpy and Gibbs free energy values for the oxide and oxycarbide phases strongly support the observed requirement for an oxygen-free environment. Moreover, the oxycarbide phase Al2OC has been observed to appear in carbon-rich environments 44 which may also be explained by the solid phase reaction given below (equation 2).…”

Section: -41mentioning

confidence: 99%

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Rapid, energy-efficient synthesis of the layered carbide, Al₄C₃

2015

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The phase-pure binary aluminium carbide, Al4C3 can be synthesised in vacuo from the elements in 30 minutes via microwave heating in a multimode cavity reactor. The success of the reaction is dependent on the use of finely divided aluminium and graphite starting materials, both of which couple effectively to the microwave field. The yellow-brown powder product was characterised by powder X-ray diffraction, scanning electron microscopy / energy dispersive X-ray spectroscopy thermogravimetric-differential thermal analysis and Raman spectroscopy. Powders were composed of hexagonal single crystallites tens of microns in diameter (Rhombohedral space group R3 ̅ m; Z = 3; a = 3.33813(5) Å, c = 25.0021(4) Å) and were stable to 1000 °C in air, argon and nitrogen. Equivalent microwave reactions of the elements in air led to the formation of the oxycarbide phases Al2OC and Al4O4C.

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Section: -41mentioning

confidence: 99%

Section: -41mentioning

confidence: 99%

Rapid, energy-efficient synthesis of the layered carbide, Al₄C₃

2015

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“…[17][18][19][20] The reduction of alumina by CO can be presented by the following reaction: Depositing on the graphite particles, Al2O can be converted to Al vapour (Reaction (6)) and aluminium carbide (Reaction (7)): Equilibrium partial pressures of CO2 (Reaction (2)), Al (Reaction (3)) and Al2O (Reaction (4)) are presented in Fig. 10.…”

Section: Discussionmentioning

confidence: 99%

Low-temperature Synthesis of Aluminium Carbide

Zhang

et al. 2011

ISIJ Int.

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The Hall-Héroult process, the only commercial technology for aluminum production requires high energy and is a major origin of perfluorocarbons and green house gases. A promising alternative process, carbothermal reduction of alumina to metallic aluminum has advantages of lower capital cost, less energy consumption, and lower emission of green house gases. Carbothermal reduction processes under development are based on formation of aluminum carbide-alumina melts at high temperatures. Solid state carbothermal reduction of alumina is possible at reduced CO partial pressure. This paper presents results of experimental study of carbothermal reduction of alumina into aluminum carbide in argon, helium and hydrogen atmospheres at 1 500-1 700°C. The reduction rate of alumina increased with increasing temperature, and was significantly faster in helium and hydrogen than in argon. Increasing gas flow rate and pellet porosity, and decreasing pressure favour the reduction.

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“…No obstante, aún existen discrepancias sobre la eficacia del Al como antioxidante y los efectos que provoca en el comportamiento posterior del material. Sin embargo, la mayor parte de los estudios realizados se han llevado a cabo en materiales refractarios reales de distintas características composicionales y microestructurales, lo que dificulta el análisis de la atmósfera existente en el material y el conocimiento y discusión de los procesos termoquímicos que tienen lugar en estos materiales (13,14,15,16).…”

Section: Introductionunclassified

Determinación experimental y termodinámica de la influencia de la relación Al/C en la microquímica y microestructura de materiales de MgO-C-Al

Serena¹,

Saínz²,

Caballero³

2007

Bol. Soc. Esp. Ceram. Vidr.

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En el presente trabajo se ha establecido entre 1100º y 1800ºC la microquímica y microestructura de materiales de MgO-C-Al con elevado contenido en MgO y para diferentes relaciones Al/C, en condiciones fuertemente reductoras. Los resultados experimentales obtenidos se han discutido en función de la estabilidad termodinámica de las diferentes fases del sistema MgO-C-Al, determinadas teóricamente a distintas temperaturas y presiones parciales de Mg(g), Al(g) y CO (g). La combinación de ambos estudios, ha permitido realizar una descripción completa del proceso de reacción que tiene lugar en las composiciones estudiadas. Palabras clave: Magnesia, grafito, aluminio, estabilidad termodinámica, relación Al/C.Experimental and thermodynamic analysis of the Al/C ratio on the microchemistry and microstructure of MgO-C-Al materials.The microchemistry and microstructure of MgO-C-Al materials with high magnesia content and different Al/C ratio have been established between 1100º and 1800ºC, under strong reducing condition. The experimental results have been discussed as a function of thermodynamic stability of different phases of the MgO-C-Al system, theoretically determined at different temperatures and partial pressures of Mg(g), Al(g) and CO(g). Both studies have allowed established a complete description of the reaction process in all compositions studied. Keywords: Magnesium oxide, graphite, aluminium, thermodynamics stability, Al/C ratio INTRODUCCIóNEl desarrollo de materiales compuestos oxido/no óxido intenta conjugar las excelentes propiedades físico-químicas a alta temperatura de los óxidos con la mejora de las propiedades termomecánicas, resistencia a la corrosión y conductividad térmica que confieren los no óxidos.Los refractarios de MgO-grafito presentan, por tanto, la elevada refractariedad del MgO con la mejora de las propiedades termomecánicas y el aumento de la resistencia a la corrosión química que aporta el grafito. Sin embargo su empleo está limitado en gran medida por la oxidación del grafito que reduce drásticamente la vida útil del material.(1,2).Con el fin de evitar la oxidación del grafito es usual la incorporación de aditivos de carácter antioxidante al material para fijar el oxigeno, por formación del oxido correspondiente, disminuyendo así la presión parcial de oxígeno, potenciando al mismo tiempo la reducción paralela del monóxido de carbono y la precipitación de carbono. Uno de los primeros elementos empleados para esta función y el de uso más extendido en la actualidad es el aluminio (3,4) aunque también se emplean el Si y el Mg(5), aleaciones de Mg-Al, carburos varios (B 4 C, SiC)(2) y carburos de aluminio tipo Al 8 B 4 C 7 (6).La inclusión de polvos metálicos como Al en la formulación de materiales de MgO-C es por tanto, una práctica común en la actualidad (3,4,7). Su reacción con los constituyentes del refractario(8) y los de la atmósfera en equilibrio dan lugar a nuevas fases que mejoran las propiedades mecánicas del material (9,10). Por otro lado, el proceso de reacción del Al ayuda a reducir...

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Formation of aluminium carbide by carbothermal reduction of alumina: Role of the gaseous aluminium phase

Cited by 40 publications

References 3 publications

Rapid, energy-efficient synthesis of the layered carbide, Al₄C₃

Rapid, energy-efficient synthesis of the layered carbide, Al₄C₃

Low-temperature Synthesis of Aluminium Carbide

Determinación experimental y termodinámica de la influencia de la relación Al/C en la microquímica y microestructura de materiales de MgO-C-Al

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Formation of aluminium carbide by carbothermal reduction of alumina: Role of the gaseous aluminium phase

Cited by 40 publications

References 3 publications

Rapid, energy-efficient synthesis of the layered carbide, Al4C3

Rapid, energy-efficient synthesis of the layered carbide, Al4C3

Low-temperature Synthesis of Aluminium Carbide

Determinación experimental y termodinámica de la influencia de la relación Al/C en la microquímica y microestructura de materiales de MgO-C-Al

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Product

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Rapid, energy-efficient synthesis of the layered carbide, Al₄C₃

Rapid, energy-efficient synthesis of the layered carbide, Al₄C₃