Thermal Shock Resistance of Ultra-High-Temperature Ceramics Under Aerodynamic Thermal Environments

摘要

A model of thermal stress field from literature with temperature-dependent thermophysical properties is updated using an appropriate expression of thermal strain due to free thermal expansion. The thermal shock resistance of the ultra-high-temperature ceramic plate under aerodynamic thermal environments is then studied by combining the proposed analytical method of heat for thermal shock. The numerical simulation is conducted to examine the theoretical model. The results from the model agree well with those from the simulation. The study shows that for the given material and thermal shock initial temperature the same heat transfer condition (product of surface heat flux and plate thickness) results in the same critical failure temperature difference. The critical failure time is inversely proportional to the square of the surface heat flux and is proportional to the square of the plate thickness, that is, the ultra-high-temperature ceramic plate has the same critical failure dimensionless time. The thermal shock resistance of ultra-high-temperature ceramics decreases as the heat transfer condition increases. The critical heat transfer condition is introduced to characterize the thermal shock resistance of ultra-high-temperature ceramics similar to using the strength in representing the fracture-resistance ability of the materials.