Quantitative Evaluation of Thermal-Shock Resistance

Abstract

Abstract The dependence of thermal-shock resistance on two parameters k and σf/Eα (when k is conductivity, σf the fracture stress, E the elastic modulus, and α the coefficient of thermal expansion) is experimentally demonstrated by the fact that the relative ratings of two materials may change with a change of quench severity. The theory of thermal-shock resistance of a disk quenched at the periphery is developed, making use of the results of Jaeger. Two criteria for failure are considered; namely, the maximum normal-stress criterion, and the criterion of maximum “risk of rupture” based on the Weibull statistical theory. Equipment for subjecting these specimens to a wide range of quench severities of known surface heat-transfer coefficients is described, and results are presented for thermal-shock tests of steatite and glass disks. The results for steatite are then utilized for determination of thermal-shock parameters by four independent methods, the results showing good agreement.