Thermal shock failure

Thermal shock (or thermoshock) failure is a very prominent failure mode in ceramics. Indeed, based on the fractographic experience of the present authors, it is apparent that more than one-third of all rejections of ceramic components are caused by thermal shock. 

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Thermal shock failures using water result from the water vapor entering the enamel layer through small, submicroscopic cracks formed at the instant of shock. The water condenses in the cracks and in the bubbles of the enamel traversed by the cracks. On subsequent heating, the vapor from the entrapped water expands to cause spalling of the enamel layer. Other quenchant Hquids, such as toluene, oils, and other organic Hquids, also cause fine, almost invisible cracks, but thermal shock failures do not result with these quenchants on subsequent heating (39). 

Thermal shock resistance is a direct function of enamel thickness. The greater the residual compressive stress in the porcelain enamel, the greater is the resistance to thermal shock failure. Thin coatings, such as one-coat enamels or the two-coat enamels having alow expansion titania covet coat, provide excellent thermal, shock resistance. 

Figure 1. For several glass ceramics, the temperature interval causing thermal shock failure, AT, is approximately inversely proportional to the linear coefficient of thermal expansion of these materials. Glasses and alumina ceramics have less thermal shock resistance than glass ceramics of comparable thermal expansion. ...

Fig. 9. Mean thermal shock failure temperature (burner test, minimum 15 units) for 400 cell ceramic monoliths and catalysts of various types.

G Montes, M Robertson and A Puckett, A characterisation of thermal shock failures in cultured marble vanity tops . Proceedings ofANTEC 88, Brookfield, CT, USA, Society of Plastics Engineers, 1988. 

Fellner, M. and Supandc, P. (2002) Thermal shock failure ofbritfle materials. Key Eng. Mater., 223, 97-106. 

Kitagawa,], etal. (1989). Effect of DPF volume on thermal shock failures during regeneration, SAE Paper No. 890173. 

Kitagawa,], et al. (1990). Analyses of thermal shock failure on large volume DPF, SAE Trans. 900113. 

Thermal shock failure occurs when tlie thermal gradients generated in a part are so pronounced that differential thermal strains exceed the ability of the material to sustain them witliout yielding or feature. 

Disadvantages. Because of their high thermal expansion, soda-lime-sihca glasses are prone to thermal shock failure, and because of their relative softness, they have limited... 

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