Molecular dynamics simulations of microstructural properties of CaO–SiO2–TiO2 fluorine-free slag systems

Abstract

The microstructural properties of F-free slag, the CaO–SiO2–TiO2 (CST) systems, are investigated by molecular dynamics (MD) simulations. The results show that in the CST system, the average bond length of Si–O remains in 1.61 Å. The addition of TiO2 contributes to the increase in the concentrations of 4-coordinated Si and 4-coordinated Ti. Increasing the amount of CaO decreases the proportion of bridging oxygen (BO) atoms and the degree of network connectivity (Q3 and Q4), suggesting the simplification of melt polymerisation. Substituting CaO with SiO2 and maintaining a constant TiO2 level causes the microstructure of the slag to become more complex. Both SiO2 and TiO2 contribute to the more complex structures of the melts. Simultaneously, Si–O–Ti linkages are more favourable than Si–O–Si or Ti–O–Ti linkages. Thus, TiO2 is regarded as network former in terms of its structure within CST system when the content of TiO2 excessed 28 mass%.