Thermal properties of 60P2O5–(40−x)Al2O3–xNa2O glasses.

Phosphate glasses are important materials in many fields. However, their usage can be limited due to water corrosion. Addition of Al2O3 significantly improves the water resistance, and as such, the glass of superior water durability can be obtained. Thus, it may be considered as a matrix for waste immobilization. In the paper, thermal properties of 60P2O5–(40−x)Al2O3–xNa2O glasses are presented. The materials were investigated with the application of DSC/TG method and observations of shape change during heating in a heating microscope. Water durability studies are also presented. It was evidenced that glass of low Na2O content crystallizes during heating, which limits their application in waste vitrification. Nevertheless, the obtained glass–ceramic material is characterized by a superior water resistance. The water durability decreases with sodium content. The obtained results are discussed from a waste immobilization point of view, and the optimal glass composition containing 15 mol% of Na2O is indicated due to it low viscosity, melting temperature and very good water resistance. [ABSTRACT FROM AUTHOR]