FORMATION OF ALUMINUM CARBIDE BY CARBOTHERMAL REDUCTION OF ALUMINA - ROLE OF THE GASEOUS ALUMINUM PHASE

Formation of aluminium carbide by carbothermal reduction of alumina un der an atmospheric pressure of argon involves the following reactions occurring from 1400-degrees-C: (i) The decomposition of alumina: 2Al2O 3 half arrow right over half arrow left 4 Al + 3O2 and the correlative formation of carbon monoxide: 3O2 + 6C half arrow right over half arr ow left 6CO (ii) The intermediate formation of the oxycarbide Al2OC fo r partial pressures of carbon monoxide of about 5 x 10(-3) Pa: 4 Al 2CO half arrow right over half arrow left 2 Al2OC (iii) The final prod uction of Al4C3, when the partial pressure of carbon monoxide becomes lower, accompanying the decomposition of the oxycarbide, may be by: 4 Al + 3C half arrow right over half arrow left Al4C3 Gaseous aluminium can be detected experimentally by an emission spectrometer from the lo west temperatures (1400-degrees-C) and all along the different steps.