Crystallization and Properties of Some Glasses Based on Li-silicates

Abstract

Crystallization in lithium silicate glasses containing progressive additions of cement kiln dust was investigated using XRD and SEM analyses. Different properties were characterized by dilatometer, microhardness, and density measurement techniques. Crystallization of the base glass is shown to give lithium di and metasilicate phases. However, the introduction of cement kiln dust in such glass leads to the development of wollastonite as well. The subsequent incorporation of cement kiln dust in the base glass increases the wollastonite crystallization in addition to dominant Li-metasilicate phases. Crystallization in long period heat-treatment shows the formation of Li₂Ca₃Si₆O₁₆ in the entire sample containing cement kiln dust. Gradual decrease of the coefficient of thermal expansion (CTE) and the Vickers hardness values takes place in the crystallized glasses, from 12.8 to 8.2 × 10₋₆ °C₋₁ (20°-500°C) and from 5.89 to 5.04 GPa respectively, with the incorporation of cement kiln dust. At the same time, the increase in density of the crystallized glasses, from 2.42 to 2.67 g.cm₋₃is observed. The results are discussed on the basis of current reported results on crystallization of glasses.

Keywords:

• Glass-ceramic
• Li-silicate
• Wollastonite