The effect of Bi2O3 and TiO2 additives on the micro structural properties of magnezit waste–quartz–kaolin–alumina ceramic system

In the present study, the aim was using natural raw material and industrial waste materials to obtain MgO-Al2O3-SiO2 (MAS) glass ceramic. The crystallization kinetics of Bi2O3 influence of on MgO-Al2O3-SiO2-TiO2 glass ceramics system was investigated by microstructural and structural properties. In this study TiO2 was nucleating agent. In addition, the fact that MAS glass-ceramics, which are high-tech ceramics, will be produced from waste materials when recycling is so important in these days. This industrial waste usage gives originality to this thesis study. In accordance with this purpose; the recipes were prepared by adding wt.%20 quartz, %35 M. Waste, %25 Kaolin, 20% Alumina ; then this raw materials and wastes %0 , %2,5, %5 ve %10 ratios Bi2O3 and %8 TiO2 excess were added and 4 different recipes have been prepared. The prescriptions giving the stoichiometric balance in the experimental part were found from the triple balance diagram of MAS (magnesium alumina silicate). The mixtures weighed precisely were mixed with 1 hour ball mill, 110oC drying during 24 hours, glass melting at 1500 oC, then graphite mould casting, and at the end annealing at 600 ° C for 1 hour. The obtained glass; to the aim for diagnose of phases XRD analysis were examined, for the determination of its thermal properties DTA, SEM analyzes were performed for the determination of microstructural properties. The glasses, at 1100 oC, 1150 oC, 1200 oC and 1250 oC; 1-3-5- and 10-hours heat treatment utilized and obtained the glass-ceramics. XRD, SEM, hardness and bulk density have been measured and calculated. Activation energy was evaluated for the crystallization of the cordierite phase formed in the studied system. The crystallization mechanism was investigated by applying DTA measurement. As a result the dominant crystallization mechanism for this system is bulk crystallization by three-dimensional growth. The average calculated values of crystallization formation of crystal phases from the glass matrix were measured to be 410 kJ mol-1 and viscous flow for the and 390 for non-added Bi2O3. It was observed that the crystallization value decreased with addition of Bi2O3. At %2.5 , 5 and 10 Bi2O3 addition, the crystallization activation energy was calculated to be 336 ± 4 kJ mol-1 , 218 ± 1 and 170 ± 3 kJ mol-1, and the viscous flow activation energy was measured 377 ± 2 kJ mol-1, 403± 7 and 407± 21 kJ mol-1, respectively. Keywords: MAS glass-ceramics, Bi2O3, Crystallization kinetics, Industrial waste