Influence of CaF₂on viscosity of aluminosilicate melts

Abstract

A model is developed to estimate the viscosity of aluminosilicate melts containing CaF2, in which the influence of chemical composition is expressed by different types of oxygen ions and CaF2 clusters. In this study, CaF2 is assumed to have no effect on the relative amounts of different structures Qi (i = 0–4) (where the superscript refers to the number of bridging oxygen in a given structural unit), but only acts as a diluter. The viscosity model can be well applied to CaO–FeO–CaF2–SiO2, CaO–Al2O3–CaF2–SiO2, CaO–Na2O–CaF2–SiO2 and CaO–FeO–CaF2–Al2O3–SiO2 melts. From the isoviscosity curves of the CaO–CaF2–SiO2 system plotted by the present model, it can be concluded that the substitution of CaF2 for CaO makes the viscosity decrease in an acidic composition area but almost keeps constant in the basic composition area.