Use of a Structural Model to Calculate the Viscosity of Liquid Silicate Systems

A viscosity model for binary and ternary silicate melts is proposed in this article. The temperature dependence of viscosity is expressed using the Arrhenius equation and the composition dependence is made through the concentration of oxygen bridges (Si–O–Si) in the silica structure. A previous proposed structural thermodynamic model is used to calculate the content of oxygen bridges. The model requires only three parameters to obtain a good agreement between experimental and calculated data for the SiO2–CaO, SiO2–MgO, SiO2–MnO, and SiO2–Na2O binary systems. The viscosity of ternary systems is calculated with the model assuming a linear function of the parameters from binary systems; however, the content of oxygen bridges is calculated using the structural thermodynamic model for ternary systems. Comparison is made between the experimental and model results for the SiO2–CaO–MgO, SiO2–CaO–MnO, and SiO2–Na2O–MgO systems. The viscosity model can take into account the effect of substituting one metal oxide for another in the ternary systems.