Thermal shock behaviour of mullite ceramic

The aim of this work is to study some aspects of the thermal shock of mullite ceramic. Mullite samples are submitted to mild thermal shock by quenching in a compressed air flow using a Biot number β=0.3. The cooling duration is 6 s with a superficial heat exchange coefficient h=600 W/m2°C. This duration is sufficient for the transient thermal stress to reach its maximal value. The critical temperature difference ΔTC found equal to 750 °C was obtained by measuring the retained mechanical strength and the Youngʹs modulus. For determining the failure time and ΔTC, we used the acoustic emission technique. Finally, the thermal shock experiments are modelled by a two dimensional cooling model, allowing a precise determination of the induced stress intensity factor KI.