Damage and Failure Characterization of Nanostructured Ceramic Coatings Under Uniaxial Tensile Loading

Ceramic coatings will be subjected to the interaction of various complex loads during service. Therefore, it is very important to study the damage evolution and failure mechanism of the ceramic coating/alloy substrate system. In this paper, based on the finite element method and by introducing the cohesive zone model, the crack initiation and propagation of nanostructured ceramic coatings under tensile loads are simulated. The results show that the cracks inside the coating are mainly induced by tensile stress, the cracks are initiated on the outer surface of the coating, and the cracks are first initiated in the middle part of the tensile specimen. In addition, based on the simulation results of crack evolution and the Taylor expansion of the control stress, the damage rate of the nanostructured coatings is characterized quantitatively to discover the failure mechanism of the coatings under uniaxial tensile load. The results show that the damage of the coating increases with the increase of the stress, and obeys the power law characteristic with the power exponent of 0.5. The simulation results are consistent with the predictions of the model.