An oxide ceramic based composite of Al2O3-SiO 2-ZrO2 (ASZ) system was developed and investigated using a pressureless sintering route. The effect of compositions of each component on the microstructure, density, and hardness properties were studied. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to investigate the phase composition of ASZ composite system. The results showed that with varying ZrO2 content, keeping the silica content constant and the alumina as a matrix, the densification tends to decrease as the content of zirconia increases starting from 10 wt. of the composition. XRD peaks suggested a fully developed alumina, mullite and zirconia phases formed by the solid and liquid phase reaction sintering. The experimental results reveal also the hardness value was in the range of 10-12.5 GPa, the highest value for a composition of 80wt. Al2O3-10wt. SiO2-10wt. ZrO2. Copyright © 2012 Inderscience Enterprises Ltd.