Surface crystallization in a Li₂O–ZrO₂–SiO₂–Al₂O₃ glass

ABSTRACT

Growth kinetics of crystallized surface layer in a LZSA glass composition, 11.7Li₂O·12.6ZrO₂·68.6SiO₂·7.1Al₂O₃ (wt%), was studied. For the production of the LZSA glass, it was used commercial raw materials (Li₂CO₃, ZrSiO₄, SiO₂, Al₂O₃) which were mixed and melted at 1550 °C for 120 min and then poured into a metallic mold. Samples of the obtained glass were cut and subjected to heat-treatments at different temperatures (825 - 925 °C) and times (30 - 150 min) for formation and growth of crystalline layer. Cross-sections of the heat-treated samples were ground and polished such that images of the formed crystallized layers could be visualized and measured by microscopy. Results showed that it is possible to obtain LZSA glasses with crystallized layers formed by β-spodumene, zircon and lithium silicate, which present thicknesses between 13 and 665 µm and grow at rates varying from 0.4 to 4.8 µm/min in the studied temperature range.

Glasses; crystallization kinetics; surface crystallization