Synthesis of cordierite ceramics with a mixture of kyanite and TALC

Cordierite based ceramics were prepared by heating a mixture of kyanite and talc. Two different mixtures were prepared: one with a coarse commercial kyanite which had a particle size of <37 μm (-325 mesh size), and another with an attrition-milled kyanite which had an average particle size of 0.7 μm. The samples were heated to 1200°C, 1300°C and 1350°C. The kyanite particle size influenced the shrinkage behavior during firing. For the sample that contained the coarse kyanite, the total contraction was nearly zero because the expansion that occurs during the decomposition of kyanite compensates for the sintering shrinkage. That expansion did not occur for the sample with the finer kyanite. The samples heated at 1350°C contained particles of cordierite dispersed in a glassy matrix, but the microstructure was finer, denser and more homogeneous for the samples that contained the finer kyanite.