: Thermal Barrier Coatings (TBCs) are widely applied to internally cooled gas turbine component parts to lower the base metal temperatures. Such coatings eventually fail due to thermal cycling and are generally subjected to large cyclic stresses. In this research, fracture failure of TBC under thermal cycling is investigated. According to microstructural attributes of as-sprayed as well as sintered plasma sprayed ceramic coatings, a model is proposed to simulate the nonlinear stress- strain behavior of plasma sprayed ceramic coatings under compression and changes of the stress- strain behavior due to sintering at high temperature. The results of the parametric analyses indicate that the major part of changes of the stress-strain behavior in the sintering process is due to surface diffusion which lowers the density of the microcracks. A numerical model is also proposed to investigate the performance of the TBC under thermal cycling. The simulation results explain the experimentally observed cracking patterns. The growth of oxide layer and the sintering of the top coat layer are realized to be the main sources of fracture in TBCs. Finally, the crack behavior in the top coat layer is investigated by using the Modified Crack Closure Integral (MCCI) technique. Keywords: Thermal Barrier Coating (TBC), Sintering, Modified Crack Closure Integral (MCCI), Fracture, Plasma Spray .
