High-temperature Viscosity Analysis of Aluminosilicate Melts and the Comparison to Empirical Models

Understanding the high-temperature viscosity of aluminosilicate near liquid–solid transition is important in the metallurgical industry and fiberization processes, but the experimental determination of viscosity is time and cost consuming. To date, a number of viscosity models have been reported, yet their applicability at such temperature remains questionable. In this paper, the high-temperature viscosities of nine aluminosilicate compounds are measured by rheometer FRS 1600, which allows precise measurements under controlled conditions. Both rotational and oscillation modes are utilized to evaluate the shear viscosity and complex viscosity. The measured viscosities are then compared with empirical models in the literature. It is found that the Urbain model and FactSage simulation output reasonable prediction on viscosities for most of compositions, with an order of magnitude error. We also found none of the models showed a good agreement for Fe-rich multicomponent systems, even Kondratiev model of which Fe content was an important design factor. The results suggest that Urbain model and FactSage simulation are a fair choice for approximating the viscosities for aluminosilicate system (35–56 wt% SiO2, 11–20 wt% Al2O3, 6–37 wt% CaO, and 2–10 wt% MgO) at 1150–1400 °C, but the viscosity models have errors at given temperature range due to their limitation in design composition and temperature.