Ceramics-Silikáty 50, (2) 88 - 97 (2006)

The development of low cost glass-ceramic based on various contents of Egyptian blast furnace slag and granite rock has been investigated. The effect of granite / slag replacements on the crystallization characteristics of the glasses and the resulting microstructure, are traced by differential thermal analysis (DTA), x-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Varieties of melilite phase of gehlenite type, wollastonite solid solution and anorthitic plagioclase phases were mostly formed depending on the granite/slag ratios in the glasses. The types of the crystallized phases formed are discussed in relation to the compositional variation of the glasses and thermal treatment applied. SEM micrographs showed that granite/slag replacement promoted a uniform volume crystallization of fine-grained interlocked microstructure, which is achieved by increasing the granite content in the glasses. The addition of LiF as nucleation catalyst enhanced the crystallization characteristics of the glasses. The increase of granite at the expense of slag in the glasses led to improve both the thermal expansion characteristics and the chemical durability of the materials investigated.