A study was conducted of the effect of a spatial variation in heat transfer coefficient during forced convection and the effect of temperature dependence of the heat transfer coefficient during free convection on the magnitude of thermal stress encountered during the thermal shock testing of brittle ceramics by the quenching method. For specimens with circular geometry, the results obtained by the finite element method indicate that, depending on the value of the Biot number, a factor of three spatial variation in heat transfer coefficient changes the tensile thermal stresses on cooling by a maximum of about 17% over the value for spatially uniform heat transfer. On heating, the corresponding tensile thermal stresses are lower by a maximum of about 6%. In free convection for a heat transfer coefficient, h, proportional to ΔTi1/4, where ΔTi is the instantaneous temperature difference between the specimen and quenching medium, the stresses are appreciably less than those for ΔTi‐independent heat transfer for the same initial value of h at the onset of the thermal quench. The validity of the dependence of h on ΔTi was established experimentally. The relevance of this result to the interpretation of thermal quenching studies is discussed.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of the American Ceramic Society|
|State||Published - Jan 1 1983|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry