Mathematic simulation of atomic structure of multicomponent oxide-fluoride melt for continuous casting machines

Abstract

Determination of relation between oxides melts properties, based on silicates and calcium alum-silicates and magnesium and their chemical composition and structure is an important condition to provide a rational slag mode in a continuous casting machines mold. A mathematical simulation of slag melts and casting powders accomplished. The oxide-fluoride system was chosen for the simulation, for which the structure after solidification was determined by experiment. Results of molecular-dynamic simulation of CaO–SiO2–Al2O3–MgO–Na2O–K2O–CaF2–FeO system, correspondent to industrial casting powders composition, used during steel casting for slag formation in a CCM mold (35.35 % SiO2; 30.79 % CaO; 8.58 % Al2O3; 1.26 % MgO; 13.73 % CaF2; 7.57 % Na2O; 0.88 % K2O; 1.82 % FeO). Taking into account the concentration, a re-calculation was accomplished to mole shares and correspondent number of ions in the model for each component calculated. Simulation of the 8-component oxide-fluoride melt with 2003 ions size in the main cube (a side length of 31.01 Å) was accomplished at the experimentally determined temperature of solidification onset (1257 K) under periodic boundary conditions and fixed volume. The Coulomb interaction was taken into account by the Ewald–Hansen method. The time step was 0.05t0, where t0 = 7,608×10–14 sec is the internal unit of time. The melt density was taken as 3.04 g/cm3 based on the experimental data. The inter-particle interaction potentials were chosen in the Born–Mayer form. According to the simulation results, the structure of sub-crystalline groups of atoms present in the melt at the temperature of the onset of solidification was determined. A discussion of the simulation results and their comparison with the literature data presented.