Ceramics-Silikáty 53 (3) 171-179 (2009)

CRYSTALLIZATION OF CALCIUM ZINC ALUMINOSILICATE GLASSES

A. A.Omar, S. A.M.Abdel-Hameed

The crystallization behaviour of some glasses in the CaO–ZnO–Al₂O₃–SiO₂ system was investigated using different heat-treatment parameters. Cr₂O₃ and CaF₂ were used as nucleating agents. Differential thermal analysis, X-ray diffraction, dilatometry and scanning electron microscopy were used in this study. Melilite, α- and β-willemite, anorthite, wollastonite, pseudowollastonite and petedunnite phases developed in the investigated glasses. The formation of compatible and incompatible phase assemblages and the effect of Cr2O3 and CaF2 are illustrated. Glass-ceramics with fine-grained microstructures and CTE values ranging from 36 to 73 × 10-7 K^-1 in the 20-700°C range were obtained.

Keywords: Glass; Glass ceramics; Willemite