Physico-mechanical, Refractory Properties and Microstructure of In-situ Mullite-Cordierite Composites

摘要

In situ mullite cordierite composites were prepared from kaolin, talc and alumina in the range 5 to 35 percent cordierite at 1 300, 1400, and 1500 deg C and 3 h soaking time. XRD and SEM results revealed the complete formation of cordierite-mullite composites at 1400 deg C. At 1500 deg C, all cordierite had transformed into mullite and glassy phase leading to a sudden and optimal densification at 20 percent cordierite. Samples of 25-35 percent cordierite did not show better densification in spite of the larger amount of melt formed from cordierite dissociation. However, the highest cold crushing strength was attained in these samples owing to their well-distributed mullite grains and compacted microstructure. All the samples revealed high thermal shock resistance at all firing temperatures, while samples fired at 1500 deg C exhibited the highest refractoriness under load through the formation of highly refractory mullite phase.