Microwave combustion synthesis of MgO-Al2O3-SiO2-ZrO2 ceramics: Sinterability, microstructure and mechanical properties

MgO-Al2O3-SiO2-ZrO2 ceramic system is considered as one of most interesting systems due to the possibility of forming cordierite-zirconia composite which has unique properties. The goal of the present work is to synthesize MgO-Al2O3-SiO2-ZrO2 ceramics by microwave combustion technique. The synthesized ceramic powders included up to 30 wt % zirconia. The prepared powder was calcined at different temperatures up to 1375 °C and the formed phases were examined by x-ray analysis (XRD). The morphology and particle size of as-synthesized and calcined powders were tested by transmission electron microscope. The synthesized powder was pressed and sintered at different firing temperatures up to 1430 °C. Bulk density and apparent porosity of sintered pellets were determined by Archimedes method. XRD was also used to investigate the phase composition of sintered bodies. Scanning electron microscope was used to examine the microstructure of sintered composites. Compressive strength and thermal shock resistance of sintered bodies were also evaluated. The results revealed that the microwave processing technique was effective to synthesize nano cordierite-ZrO2 containing composites. The addition of zirconia led to improving the thermal shock resistance, stabilizing the composites up to 1400 °C without deformation and led to delaying their fusion as compared with that composition without zirconia.