Diffusive dissolution of α-alumina in industrial soda-lime silica glass

Abstract

This study advances the understanding of alumina dissolution mechanisms in industrial soda-lime-silica glass. Electron Probe Micro-Analysis (EPMA) revealed diffusion-controlled behavior between 1300 and 1450 ° C, with interface melt compositions varying significantly with temperature. These variations align with thermodynamic predictions. At temperatures $\ge$ 1400 °C, the interface enters the peraluminous field, while at lower temperatures, it lies in the domain of excess charge-balancing cations. Compositional profiles, including uphill diffusion at $\ge$ 1400 °C, necessitate a multicomponent diffusion matrix approach. Two primary exchange mechanisms are identified: the first involves alumina and charge-balancing cations (mainly Mg+Ca), and the second involves silica and charge-balanced alumina. However, alumina diffusivity can be approximated using an effective binary diffusion coefficient (EBDC), which correlates with the viscosity of the interface melt, even when a viscosity maximum is present. These results emphasize the importance of multicomponent approaches to understanding mineral dissolution and diffusion, particularly in peraluminous systems.