抄録
For evaluating the thermal shock resistance of ceramics precisely by quenching test, one must know the heat transfer coefficient h between quenching liquid and surface of specimen, when a critical temperature difference Δθc is measured. However, few studies have been devoted to quenching liquids applicable to thermal shock test of ceramics, and the heat transfer coefficient is estimated from the Δθc value when needed. In general, h in a quenching liquid exhibits a maximum value in the temperature region where the heat transfer mode changes from bubble boiling to transition stage. Therefore, it may be meaningless to measure the Δθc value for some ceramics, which are fractured by thermal stress near the region of maximum h. In this study, the temperature changes at two different positions in the specimen were measured by using various quenching liquids and the results were analyzed. The useful so-called heat transfer coefficient for thermal shock test was obtained from the temperature difference. On the basis of this method, the mixture of mineral oil and butanol was proved to be a suitable quenching liquid for thermal shock test, in which h did not show maximum in the usual quenching temperature difference range of 150 to 450°C of ceramics.
