Thermodynamics of Phase Equilibria in FeO-TiO2-Al2O3 System.

This scientific paper discusses the information on the structure of the three-component system FeO-TiO2-Al2O3, which is necessary for the creation of heat-resistant oxide materials. The structure of binary systems: FeO-Al2O3, FeO-TiO2, and Al2O3-TiO2 is described, and the data on the FeO-TiO2-Al2O3 system are presented. The thermodynamic data of all compounds of the system are given, on the basis of which the change in the Gibbs free energy in the temperature range of 8 00-1 900 K for twenty-one exchange reactions was calculated. It has been established that the triangulation of the FeO-TiO2-Al2O3 system changes in five temperature ranges: up to 1 408 K (TiO2 exists in the polymorphic modification-anatase), 1 408-1 537 K (TiO2 exists in the polymorphic modification-rutile and pseudobrookite is stable), 1 537-1 630 K (thialite is stable), 1 630-2 076 K (rearrangement cannot occur) and above 2 076 K (the presence of the stoichiometric compound Al4TiO8 is allowed). Two-phase equilibria up to 1 408 K are stable: Al2O3-FeTiO3, FeTiO3-FeAl2O4, and FeAl2O4-Fe2TiO4; in the temperature range of 1 408-1 537 K: FeAl2O4-TiO2, FeAl2O4-FeTi2O5, FeAl2O4-FeTiO3, and FeAl2O4-Fe2TiO4; in the temperature range of 1 537-1 630 K: FeAl2O4-TiO2, FeAl2O4-FeTi2O5, FeAl2O4-FeTiO3, FeAl2O4-Fe2TiO4, and FeAl2O4-Al2TiO5; in the temperature range of 1 630-2 076 K: FeTi2O5-Al2TiO5, Al2TiO5-FeTiO3, FeTiO3-Al2O3, FeTiO3-FeAl2O4, and FeAl2O4-Fe2TiO4; over 2 076 K: FeTi2O5-Al2TiO5, FeTi2O5-Al4TiO8, Al4TiO8-FeTiO3, Al4TiO8-Fe2TiO4, Al4TiO8-FeO, and Al4TiO8-FeAl2O4. [ABSTRACT FROM AUTHOR]