The thermal shock behaviors of yb:YAG transparent ceramics

The thermal shock resistance is a major concern of the Yb:Y3Al5O12 (Yb:YAG) transparent ceramic considered as a potential solid-state laser material. Its thermal shock behavior was investigated by the standard water-quenching and indentation-quenching thermal shock measuring methods. The residual flexural strength and Vickers radial cracks were measured as a function of thermal shock temperature difference (ΔT). It showed that after the thermal shocking of ΔT=130°C a reduction in residual flexural strength was observed, and there was a ΔT of 120°C at which the longitudinal cracks (aligned parallel to the sample's length) grew radically. A good correspondence was found between the results of the thermal shock critical temperature difference (ΔTc) obtained by the standard water-quenching method and estimated by the indentation-quenching test. The analysis of the indentation fracture mechanics was used to account for the cracking responses. The analysis confirmed that the thermal stress induced by the thermal shock is much greater in the transverse direction than in the longitudinal direction, resulting in the unstable longitudinal cracks propagated at first.