Microstructure Development in Mullite-Cordierite Ceramics

The evolution of the microstructure in mullite-cordierite bodies containing 36 wt% cordierite has been studied in samples fired at 1490°C for varying times. This material reaches its final density very quickly once the cordierite becomes molten. However, densification, which is not accompanied by any significant coarsening of the mullite phase, appears almost entirely to result from particle–particle rearrangement. Consequently, the ultimate density of these materials appears to be limited by the inability of molten cordierite to penetrate all mullite-mullite grain boundaries.