Molecular Dynamics Simulation Research of the Effect of K+ Ions on the Microstructure of Al2O3-SiO2-K2O Silicate Melts.

Understanding the structural and dynamic properties of Al2O3-SiO2-K2O melts is essential for optimizing their performance in high-temperature industrial applications. In this study, molecular dynamics simulations were employed to study the effect of the K2O content on the microstructure of the Al2O3-SiO2-K2O melt, with a focus on viscosity variations and the distribution of ionic associations. The results reveal that Si-O predominantly exists in a stable tetrahedral configuration. The increase of K2O content increases the coordination number of Al-Si while decreasing that of K-Si, in line with the computed distribution of associations. The K2O content has a minimal effect on the O-Si-O bond angle distribution, suggesting that K+ does not disrupt the [SiO4]4- tetrahedral structure. However, the average Si-O-Si bond angle initially decreases and then increases, indicating a transition from tightly packed to more loosely arranged [SiO4]4- tetrahedra. This structural transition explains the observed viscosity trend, which first increases and then decreases. Furthermore, ion diffusion force analysis reveals that the self-diffusion coefficient of Si particles decreases and then increases with the K2O content, further supporting the viscosity results.