Atomic-molecular perspectives on local high-temperature structure and transport properties of CaCO3-foamed glass

Abstract

Significant gaps remain in understanding of gas-melt interfaces in foamed glass systems. We attempt to address these gaps by reporting on the transition of local structure, ionic (molecular) diffusion, and melt viscosity of CaCO3-foamed soda-lime-silica glass using molecular dynamics calculations and experimental analyses. Our calculations show that despite the continual increase in network modifying CaO, the melt network experiences an abnormal polymerization process in the initial stage because of Na ion penetration from the melt skeleton to the interface. The percolation probability decays from the surface to the center of melt because of the gradual polymerized network structure, boosting nonmonotonic changes in the [SiO4] species, equilibrium constants, and average residual charge per O atom. Furthermore, the diffusion capacities of melt ions and CO2 molecules peak at 6 wt% CaCO3 addition, attributed to the combined effects of melt depolymerization and interface constraint. The viscosity jump occurring at 1 wt% CaCO3 addition results in the optimal sample with an even cellular glass framework and strong matrix. These findings contribute to the precise control of foamed glass with optimal performance.