Factors influencing the thermal shock behavior of ceramics

The application of ceramics often requires resistance to tensile stresses developed by steep thermal gradients. Among the most popular test techniques to evaluate thermal stress/shock resistance is the down-quench test where the strength retained is determined after the sample is quenched from an elevated temperature into a fixed temperature bath. When the temperature difference is sufficient to cause a loss in strength, this temperature difference represents the critical temperature drop, ΔTc The thermal shock resistance becomes greater as ΔTc increases. However, heat conduction within the sample during quenching results in temperature (and surface tensile stresses) gradients that are less in thin samples as compared to thick samples. In fact, the ΔTc values for a given material will decrease and then reach or approach a constant value with increase in sample thickness.