Effective Mechanism of B 2 O 3 on the Structure and Viscosity of CaO–SiO 2 –B 2 O 3 ‐based Melts

To have a further study for fluorine‐free mold fluxes, the structure, viscosity characteristics, and crystallization behavior of CaO–SiO 2 –B 2 O 3 ‐based melts are studied combing molecular dynamics (MD) simulation and various experiments. The results show that, in the ternary CaO–SiO 2 –B 2 O 3 glass system, stable structural units of [SiO 4 ] 4− tetrahedral, [BO 3 ] 3− trihedral, and [BO 4 ] 5− tetrahedral formed and the B 2 O 3 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 B 2 O 3 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 (B 2 O 3 ) = 4–6 wt% shows the characteristics of alkaline slag, whereas it shows the characteristics of acidic slag in the range w (B 2 O 3 ) = 8–12 wt%. The MD simulation and experiment results are verified and complemented each other.