EFFECT OF MgO and CaO ON THE STRUCTURE AND FIBRE SPINNABILITY OF ALUMINOSILICATE GLASS MELTS WITH A MOLECULAR DYNAMICS SIMULATION AND RHEOLOGICAL STUDY

Aluminosilicate glass serves as the fundamental system for high-modulus and high-strength glass fibres, with the melt spinnability crucial for the production of fibres. This study employs molecular dynamics simulations to investigate the structure of glass melts, examining the impact of substituting Al₂O₃ with CaO and MgO on the bond lengths, coordination numbers, and structural units. Additionally, rheological properties were explored through DSC, high-temperature viscosity, with assessments of the fibre spinnability. The findings revealed that the simulated structure of the glass melts aligned with previous studies. As the (Ca+Mg)/Al ratio increased, the coordination numbers of silicon and aluminium deviated from four, with a markable decrease in the concentrations of the bridging oxygen and Q⁴ units in the glass networks, signifying the structural degradation in the glass melt. The reduced polymerisation of the glass melt led to a decrease in the high-temperature viscosity. The fibre spinnability index (Kfib) declined, yet it remained larger than one, indicating excellent fibre capability for glass melts. Finally, the relationship between Kfib and NBO/T can be expressed as Kfib=25414.5*exp(-9.399* NBO/T)+2.981, with an R² of 0.981, providing a predictive tool through high-temperature molecular dynamics simulations and the established relationship between Kfib and NBO/T.