Molecular dynamics simulations study on structure and mechanical properties of Na2O–CaO-Al2O3-B2O3-SiO2 glasses with different Al2O3/B2O3 ratio

Abstract

The structure and mechanical properties of Na2O–CaO-Al2O3-B2O3-SiO2 glass were simulated using molecular dynamics simulations, with Al2O3 replacing B2O3. The simulated elastic modulus (E) increases while the fracture toughness (KIc) decreases, consistent with the experimental findings. The increase in Al2O3/B2O3 enhances the proportion of [AlO4] in the glass network, while reducing the proportion of [BO4] and [BO3], thereby increasing dissociation energy and atomic packing density, ultimately improving the E of the glass. The fracture process of glasses involves both elastic and plastic deformations. Elastic deformation primarily includes bond length extension, bond angle bending, and changes in coordination numbers of Ca2+ and Na+. Plastic deformation primarily results from changes in coordination numbers of B3+ and Al3+ during stretching, with reduced [BO3] and [BO4] decreasing the plastic region and subsequently reducing KIc. This study will provide a theoretical basis for adjusting E and KIc values for aluminoborosilicate glass.