Strengthening Potentials of Lithium-Doped Soda–Lime–Silicate Glasses Through Surface Crystallization of Quartz-ss

Abstract

The formation of a crystallized surface layer, having a lower coefficient of thermal expansion (CTE) than the parent glass, can be exploited to place the glass surface under compression during cooling from crystallization temperature and hence improve mechanical properties. In our study, we focused on the understanding of the compositional dependency of the surface crystallization of quartz solid solutions (Qz-ss) with potentially low CTE. Specifically, we investigated the crystallization of melt-prepared soda–lime–silicate glasses with variable Al₂O₃ content that were doped with lithium in exchange for sodium. Further, the role of ZnO and MgO in the crystallization was evaluated. Despite rather complex glass compositions, the observed cell parameters of the obtained Qz-ss are close to the corresponding ternary Li₂O─Al₂O₃─SiO₂ (LAS) system. Further, a simple model was applied to predict the in-plane stresses in the surface. For modeled compositions down to 5.5 mol% Al₂O₃, formation of a compressive layer for the complete range of the crystalline content can be observed. Our findings illustrate the potential of strengthening glasses through surface crystallization as an alternative to thermal- and chemical strengthening to make glass-packaging more weight competitive. The results can help to optimize glass compositions that can be strengthened by this method.