ABSTRACT
This paper is mainly directed toward development of tough glass-ceramics by improving the mechanical properties of cordierite glass-ceramics from modified Egyptian basalt rocks using different amounts of zirconia (ZrO2). Crystallization behavior of modified basalt glass was studied. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to study the phases developed and microstructure. Microhardness was measured for free and ZrO2 containing glass-ceramics at different heat-treatments to study the effect of adding ZrO2; on the hardness of these samples. Toughness increased with increasing amount of transformable ZrO2, which process is probably caused by crack deflection due to the high stress field around the transformed ZrO2.