A NUMERICAL STUDY ON THERMAL FRACTURE OF PRECRACKED CERAMIC COATINGSIN HIGH-HEAT-FLUX ENVIRONMENT

The thermomechanical fracture and interface delamination of thermal barrier coatings (TBCs) in a high-heat-flux environment is the result of large surface temperature and thermal gradient across the coating thickness and the resulting viscoplastic deformations induced in the ceramic material. The maximum coating surface temperature has been used as the key loading parameter in previous studies. The current study explores the effects of several other thermal loading parameters on thermomechanical response and fracture behavior of TBCs with or without preexisting surface cracks. Results show that for a constant maximum surface temperature, the thermal fracture of the coating is increased by (i) an increased temperature difference across the coating, (ii) longer heating duration, and (iii) more aggressive coating surface cooling after heating. These results provide insights into TBC thermal fracture mechanisms and can potentially improve the design of the morphology of preexisting cracks in the coating to reduce fatal interface fracture.