In order to clarify the failure behavior of plasma sprayed thermal barrier coating (TBC) systems under the complicated modes of thermal-mechanical-chemical loadings, the stress rupture property evaluation and failure analysis were conducted in air and high-temperature corrosive environments for two kinds of ZrO_2-Y_2O_3 TBC systems ; one is an advanced type with the segmented top-coat and another is a conventional one. Static creep loading was found to cause the typical creep failure for both TBC systems even in the aggressive environment with almost similar manner to in air. On the contrary, it was revealed that dynamic fatigue loading tends to bring about a significant rupture life reduction both in air and in corrosive environment, since the penetration crack pre-existing in the top-coat is capable to provide a nucleation site for the fatigue crack. For the TBC system with the segmented top-coat, however, the even distribution of a number of fatigue cracks is effective to suppress substantially a rapid crack propagation, so as to result in the prolonged failure life as compared to the conventional TBC system.
