Preparation and characterization of nucleated glass-ceramics based on basaltic rocks

Glass-ceramics were prepared from basaltic rocks and by-pass cement dust. The effects of addition of the nucleating agents Cr2O3, ZrO2, and CaF2 on crystallization, phase assemblages, and microstructure were investigated. The glasses were melted at a temperature of around 1400 degrees C and heat-treated at 1000 degrees C for 2 h; the produced glass was examined by DTA, while glass-ceramics was examined by XRD and SEM. The presence of Cr2O3, ZrO2, and CaF2 was found to enhance and favor the crystallizability of wollastonite, quartz formation, and retarded the formation of gehlenite. Cr2O3 and ZrO2 are much better than CaF2 in promoting homogeneous nucleation as well as in the growth of the extremely fine-grained microstructure of aluminous pyroxene, wollastonite, quartz, and magnetite with uniform crystal size that is below 50 nm in the glass containing Cr2O3. Mechanical and physical properties, such as microhardness, bending strength, density, and thermal expansion coefficient of the glass have been examined. The results demonstrate that the glass-ceramics have a potential for a wide range of application, such as building materials.