An Avramov-based Viscosity Model for the SiO2-Al2O3-Na2O-K2O System in a Wide Temperature Range

A modified Avramov equation is employed to describe the viscosity of silicate melts in the SiO2-Al2O3-Na2O-K2O system and its subsystems with associate species obtained from thermodynamic description and used as structural units. Two modifications to the Avramov equation are proposed: i) a stronger dependence of viscosity input of each structural unit on its concentration ii) the “fragility” parameter dependent on the melt composition at a given point. The model describes the viscosity reasonably well for most of the experimental data in the wide compositional range and in a temperature range from fully liquid to supercooled melts. Approaches to further improve the model are discussed