アルミナの高温炭素還元に関する基礎研究

抄録

For the purpose of obtaining fundamental thermodynamic data for the carbothermic reduction of alumina, two types of experiments were carried out. In the first type of experiments, alumina was reduced with graphite powder at 2173K in a graphite crucible in an atmosphere of argon in the presence of iron at 2173K. In the second, a liquid Al-Fe-C ternary alloy was equilibrated with both graphite and Al₄C₃ in a graphic crucible in an atmosphere of argon at temperatures between 2073 and 2373K.
Alumina was reduced fairly fast and the aluminum content in the resultant Al-Fe-C alloy increased with time for at least the first 90min, but the evaporation of aluminum from the alloy and the formation of Al₄C₃ through the reaction between Al in the alloy and C from the crucible caused the aluminum content to decrease gradually. From the equilibration experiments it has been found that the activity coefficient of Al in the Al-Fe-C alloy and the equilibrium alloy composition can be adequately obtained by applying the regular solution model to the liquid alloy and by using the data of a functions available from literature along with the standard Gibbs energies of formation of the existing chemical species in the system.