A Thermodynamic Model for Evaluation of Mass Action Concentrations of Ce 2 O 3 -contained Slag Systems Based on the Ion and Molecule Coexistence Theory

Abstract According to the ion and molecule coexistence theory (IMCT) for molten slags and corresponding phase diagrams, a thermodynamic model for the evaluation of mass action concentrations (designated by N i for structure unit i) for Ce 2 O 3 -Al 2 O 3 , CaO-Al 2 O 3 -Ce 2 O 3 and CaO-Al 2 O 3 -SiO 2 -Ce 2 O 3 slag systems has been formulated. The results show that when the mole fraction of Ce 2 O 3 is at 0.49 in the binary slag, the mass action concentration of Ce 2 O 3 ·Al 2 O 3 achieves its maximum value 0.90. In a composition area of CaO/Al 2 O 3 (mass fraction ratio) from 0.7 to 1.5 and Ce 2 O 3 content (mass fraction) from 0 to 45% of the ternary slag at 1773 K, the results show that trends of calculated N Al 2 O 3 are in good agreement with reported measured trends of a Al 2 O 3 . The iso-curves of N Ce 2 O 3 and N CaO are also drawn from the calculated results. A thermodynamic model of the equilibrium between 55.83%CaO-23%Al 2 O 3 -11.17%SiO 2 -10%Ce 2 O 3 quaternary slag and molten steel containing aluminum has been further discussed. Results indicate that certain content of Ce would be dissolved in steel, which increases with the increasing of temperature and aluminum content, and when the aluminum content is 0.02%, the corresponding cerium content is in the range of 1.87 to 13.30 ppm at 1873 K. In summary, using Ce 2 O 3 to replace Al 2 O 3 can effectively reduce N Al 2 O 3 , certain content of Ce can dissolved in steel.