Thermodynamic Analysis of the Deoxidizing Ability of Strontium in Liquid Iron in the Presence of Aluminum

• Published in: Steel in translation 2021-10, Vol.51 (10), p.710-717
• Main Authors: Makrovets, L. A., Samoilova, O. V., Mikhailov, G. G., Bakin, I. V.
• Format: Article
• Language: English
• Subjects: Aluminates; Aluminum; Aluminum oxide; Chemical equilibrium; Chemistry and Materials Science; Corundum; Deoxidizing; Electrolytes; Hercynite; Interaction parameters; Iron and steel making; Liquid metals; Materials Science; Mathematical analysis; Phase diagrams; Solid solutions; Strontium; Strontium oxides
• ISSN: 0967-0912; 1935-0988
• DOI: 10.3103/S0967091221100090

A phase diagram for the FeO–SrO–Al 2 O 3 ternary oxide system has first been constructed, is which hercynite FeAl 2 O 4 and strontium aluminates Sr 4 Al 2 O, Sr 3 Al 2 O 6 , SrAl 2 O 4 , SrAl 4 O 7 , and SrAl 12 O 19 can form. According to the calculation, solid solutions of oxides are not formed in the system, which is consistent with the literature data. In the simulation, the optimum energy parameters of the theory of subregular ionic solutions have been selected for the oxide melt components (FeO, SrO, and Al 2 O 3 ). The thermodynamic analysis of the deoxidizing ability of strontium in liquid iron in the presence of aluminum has been made by constructing the surfaces of solubility of strontium and aluminum in a metal at steelmaking temperatures of 1550 and 1600°C and carbon concentrations of 0.1 and 0.4%. The equilibrium constants of the reactions of formation of strontium aluminates Sr 3 Al 2 O 6 and SrAl 2 O 4 from the metal melt components have been calculated for the temperature range of 1550–1650°C. It has been found that the rest of the strontium aluminates can form in a liquid metal only at temperatures above 1750°C. A thermodynamic database for the investigated systems is presented, which includes temperature dependences of equilibrium constants for the reactions occurring between components, first-order interaction (Wagner) parameters for elements in liquid iron, and energy parameters of the theory of subregular ionic solutions (for the oxide melt). The calculation has shown that strontium monoaluminate SrAl 2 O 4 and corundum Al 2 O 3 are the most probable products of the interaction in the Fe–Al–Sr–O and Fe–Al–Sr–C–O systems.