Zeolite usage as source of silica to produce cordierite in MgO-Al2O3-SiO2 system

In this study, natural zeolite was used as source of silica to produce cordierite. MgO and Al2O3 were added to zeolite to obtain the cordierite stoichiometry. Mixture of these raw materials was mechanically activated for different durations. The mechanically activated powder mixture was characterized using XRD, DSC, SEM, specific surface area, and particle size analyzer. The pycnometer method was used to measure the densities of mechanically activated powder mixtures. Mechanically activated for 60 min powder mixture was sintered at 1150-1350 degrees C for 1 h. The sintering behavior of the samples was determined by measuring the linear shrinkage, density, and apparent porosity. The phases in the sintered samples were identified by XRD. Cordierite and spinel phases were detected for sintered at a temperature higher than 1150 degrees C but corundum accompanied to cordierite and spinel at 1150 degrees C. The microstructure of the samples was examined using both SEM and AFM. The sintering behavior and microstructural properties of the samples changed with an increase in the sintering temperature. As the apparent porosity increased with increasing sintering temperature, linear shrinkage and density values decreased. Density values were determined as 2.31-2.69 g/cm(3) depending on the temperature. The grains coarsened at higher temperature and the average grain size depending on the temperature was 1.34-1.96 m. From the results optimum sintering temperature was determined as 1250 degrees C. Dense material was produced at a temperature as low as 1250 degrees C using zeolite as raw material