Effective Mechanism of B2O3 on the Structure and Viscosity of CaO–SiO2–B2O3‐based Melts

Abstract

To have a further study for fluorine‐free mold fluxes, the structure, viscosity characteristics, and crystallization behavior of CaO–SiO2–B2O3‐based melts are studied combing molecular dynamics (MD) simulation and various experiments. The results show that, in the ternary CaO–SiO2–B2O3 glass system, stable structural units of [SiO4]4− tetrahedral, [BO3]3− trihedral, and [BO4]5− tetrahedral formed and the B2O3 addition polymerizes the Si–O network structure to some extent, whereas the influence on B–O network structure various with its content. In fluorine‐free mold fluxes, the viscosity at 1300 °C and melting temperature decrease with B2O3 addition, whereas the polymerization degree of slag network structure changes little, indicating that the melting property change plays a predominant role in decreasing the viscosity at 1300 °C. Moreover, due to the solid precipitation, the viscosity‐temperature curve of fluorine‐free slag in the range w(B2O3) = 4–6 wt% shows the characteristics of alkaline slag, whereas it shows the characteristics of acidic slag in the range w(B2O3) = 8–12 wt%. The MD simulation and experiment results are verified and complemented each other.