A new method for assessing the structural safety of refractory ceramics based on a three-factor comprehensive criterion

Abstract

Traditional structural safety criteria are difficult to apply in assessing the structural safety of refractory ceramics. Herein, a three-factor comprehensive criterion for structural safety assessment of high-temperature refractory ceramics is proposed based on the failure mechanism of refractory ceramics. For the critical temperature difference criterion, the temperature of refractory ceramics changes sharply (530 °C) after the boiler stop for 120 s. Correspondingly, the left critical crack length is found to be 21 μm and the crack finally propagates to 10.87 cm (with a crack density of N = 1 cm−3) under thermal shock. For strength attenuation criterion, the cracks initiate when the compressive and tensile stress values caused by thermal shock exceed the inherent strength of refractory ceramics. Hence, the average stress of 20 MPa can be selected as the applied stress level, where the calculated life of refractory ceramics is comparable to the actual life. For the stress intensity factor criterion, the stress intensity factor (K I ) increases with the increase of crack depth (a) and crack length (c) during crack propagation, but it decreases when a and c increase to certain values. These results reveal that the three-factor comprehensive criterion is highly applicable in analyzing the failure of refractory ceramics, providing support for the maintenance decisions during practical applications.