Thermal shock resistance of ceramic materials in melt immersion tests

A melt immersion test is applied to determine the relative resistance of ceramic materials to thermal shock failure under high heat flux conditions. The testing method is demonstrated mainly for Al₂O₃ pellets, while AlN is included to represent elevated thermal shock resistance. In order to quantify the resistance to crack formation, the critical temperature difference ΔT_c between sample and metal melt is determined from the failure probability distribution of a set of pellets.

In quenching tests correspondence of ΔT_c with the thermal shock parameter R = σ(1 − μ)/E was found, if the initial surface temperature of the sample was correctly estimated. This assessment was the main concern of the evaluation work.

ΔT_c resulting from heating tests was correlated with the maximum tensile stress in the sample by modeling calculations. The stress limits determined show that the ultimate bending strength could serve as a rough approximation for the materials tested.