Ceramics-Silikáty 46, (1) 15 - 23 (2002)

The effects of compositional variation, nucleation catalyst and thermal treatment on the nature, type and stability field of crystallizing phases and microstructure formed in CaO and/or MgO aluminosilicate glasses are described using differential thermal analysis (DTA), X-ray powder diffractometry (XRD) and scanning electron microscopy (SEM). Wollastonite solid solution was formed in calcium aluminosilicate glass-ceramics, however, with MgO replacing CaO, pyroxene solid solution was developed. The addition of the nucleants brings varieties of aluminosilicate phases e.g., plagioclase, melilite and spodumene developed together with fluorite, fluorosilicate and/or TiO₂-bearing phases. Intense uniform bulk crystallization with fine-grained microstructure was achieved by an addition of TiO₂ or CaF₂ rather than LiF. The role of the nucleating agents during the formation of the crystal phases and the microstructure of the resultant glass- -ceramics are discussed.