This paper gives consideration to the three-component FeO–MgO–TiO2 system that is a part of the four-component MgO–Al2O3–FeO–TiO2 system which serves to produce materials with valuable properties. The structure of binary FeO–TiO2 and MgO–TiO2 systems is described and the available data on the FeO–MgO–TiO2 system are analyzed. We present the thermodynamic data on all system compounds and calculate change of the free Gibbs energy in the temperature range of 800 to 1900 K for three exchange reactions. It was established that the triangulation of the FeO–MgO–TiO2 system changes in three following temperature ranges: at the temperatures of up to 1115 К, at 1115 to 1413 К (the restructuring of conodes here occurs) and above 1413 K (stable pseudobrookite is formed). It was shown that the following two-phase equilibria are stable: MgTi2O5–FeTiO3, FeTiO3–MgTiO3, MgTiO3–Fe2TiO4, Fe2TiO4–Mg2TiO4 and Mg2TiO4–FeO at the temperatures of up to 1115 K; MgTi2O5–FeTiO3, FeTiO3–MgTiO3, FeTiO3–Mg2TiO4, Fe2TiO4–Mg2TiO4 and Mg2TiO4–FeO in the temperature range of 1115 to 1413 K; and MgTi2O5–FeTi2O5, MgTi2O5–FeTiO3, FeTiO3–MgTiO3, FeTiO3–Mg2TiO4, Fe2TiO4–Mg2TiO4 and Mg2TiO4–FeO at the temperatures of above 1413 K.

Among the materials that attract attention from the point of view of creating refractory products with increased heat resistance, one can single out materials based on compositions of the MgO – Al2O3 – TiO2 system. As a result of the thermodynamic analysis of the MgO – Al2O3 – TiO2 system, it was found that the partition of the system into elementary triangles will change in three temperature ranges: I – up to 1537 K, II – in the temperature range 1537 – 2076 K and above 2076 K. It has been established that up to a temperature of 2076 K there is a concentration range of spinel phases: magnesium aluminate spinel – quandylite. Above 1537 K, there is a concentration range: tialite – karroite, which meets the requirements for materials with high heat resistance. The elementary triangle TiO2 – Al2TiO5 – MgTi2O5 can be used to obtain heat–resistant materials based on Al2TiO5 stabilized by MgTi2O5. To obtain heat–resistant periclase–spinel materials, an elementary triangle Mg2TiO4 – MgAl2O4 – MgO is recommended, in which only compounds with a cubic crystal lattice are present. Thus, the division of the MgO – Al2O3 – TiO2 system into elementary triangles and the analysis of the geometrical–topological characteristics of the phases of the system made it possible to select in the system under study the regions of compositions that have optimal properties for obtaining materials with the specified optimal properties.

No abstract

No abstract

Prediction of the phase composition is one of the most important tasks in the development of new refractory materials and their operation in thermal units. The most complete information on phase interactions and thermodynamic stability of phase combinations is contained in the phase diagrams. The article presents thermodynamic studies of the three - component system MgO – FeO – Al2O3, which is of great interest for the production of refractory materials with high performance characteristics. Based on the analysis of binary systems of this system, it was found that, the stable phases are MgO, FeO, Al2O3 and MgAl2O4, FeAl2O4. The results analysis of calculating the Gibbs energy for the reaction (FeO + MgAl2O4 = MgO + FeAl2O4) indicates the thermodynamic stability of the phases combination of MgO, FeAl2O4 to a temperature of 1141 K. Above the temperature of 1141 K FeO and MgAl2O4 are stable phases. Thus, in the system MgO – FeO – Al2O3 up to the temperature of 1141 K, the phases MgO – FeAl2O4 and MgAl2O4 – FeAl2O4 coexist, above this temperature — FeO – MgAl2O4 and MgAl2O4 – FeAl2O4. The data obtained make it possible to predict thermally stimulated phase changes that give the effect of thermoplasticity and will be important for obtaining refractory materials with high performance characteristics based on the MgO — FeO — Al2O3 system.