Thermal stress analysis of cordierite materials subjected to thermal shock

Cordierite disks were obtained by slip casting and sintering at 1,450 °C for 2 h. Sintered disks were indented at the center of one flat surface. The fracture strength of indented disks was measured in biaxial flexure. The critical temperature differential was determined by sudden cooling of the center of the indented surface at high temperature, using a high-velocity air jet at room temperature. The initial temperature was successively increased by 10 °C until crack propagation was detected with the naked eye. Temperature and stress distributions during air impinging were calculated by a finite element analysis. The heat transfer coefficient was estimated by fitting experimental temperature profiles. A radial variation of the coefficient that considers its increment beyond the stagnation region and a diminution toward the disk periphery was assumed. The calculated cordierite thermal stresses were analysed in relation to experimental data. Also, the comparison with alumina tested in similar conditions was included.