The suddenly catastrophic reduction of the strength of materials in thermal shock is a long-standing problem in the thermo-structural applications of ceramics. The mechanism of reduction is traditionally considered to be crack initiation when the stresses induced by a thermal gradient exceed the strength of the materials. Therefore, studying the crack patterns both on the surface and in the interior of the ceramics after thermal shock plays a key role in understanding the mechanism of strength reduction
A team of researchers, led by SONG fan, at the Institute of Mechanics, Chinese Academy of Sciences, has been studying on the crack patterns. The crack patterns generated in a real ceramic plate and in a plate stacked by ceramic slabs under quenching are experimentally studied. The results here reveal that there are some distinct differences between the two crack patterns. The reasons that caused the differences are the size and boundary effects of the slabs. These crack patterns are very useful to understand the failure mechanisms of ceramic materials in thermal shock.
The research entitled “Crack Patterns in Ceramic Plates after Quenching” has been published online in JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 93(10), 3006-3008, DOI: 10.1111/j.1551-2916.2010.03971.x
Fig. Thermal shock crack patterns on the interior surfaces of the real plate and the slabs in the stacked plate quenched in water at DT of (a), (b) 180 K; (c), (d) 230 K; and (e), (f) 380 K, where narrow bands stand for the surfaces and wide bands show the interior surfaces.