A Raman-Structure Model for the Viscosity of SiO2-CaO-Al2O3 System

The relationship between structure and viscosity of molten slags is investigated using the Raman spectroscopy technique. To this end, a group of 20 synthetic slags in the SiO2-CaO-Al2O3 ternary system is considered. The slag compositions are close to industrial slags in silicon and ferrosilicon production, namely SiO2 contents of 35 to 75 wt pct, CaO contents of 10 to 40 wt pct, and Al2O3 contents of 5 to 40 wt pct. Using a green source laser with 532 nm wavelength, the Raman spectra are measured within the wavenumbers on the order of 200 to 1300 cm−1. To model viscosity using the Raman spectroscopy data, the ratio of low and high wavenumber vibrational bands is introduced as a structure-related Raman parameter (R). The Arrhenius equation is employed for the temperature dependency of the slag viscosity, where its parameters are linked to the R parameter through curve fitting. To model the relationship between structure and viscosity, experimental viscosity data are adopted from the literature. Comparing the model predictions and experiments, a good agreement is found between the model and measured values of viscosity.