Abstract
Failure of thermal barrier coating (TBC) layer, especially spalling-off of ceramic coating layer, results not only in degradation of thermal barrier properties. but also in crucial damage to turbine components. The spalling of ceramic coating layer will follow the crack initiation on propagation along the interface between ceramic top-layer and metal bonding layer. In the present study fatigue crack growth tests of TBC with various porosity were carried out at room and elevated temperatures. It is found that the interface crack induced by a pre-introduced notch propagates along the interface under mixed mode condition, and its growth behavior can be well characterized by using the parameter [numerical formula]. which corresponds to the change of energy release rate. It is also found that the crack propagation resistance decreases with the increase of the porosity of the top ceramic coating. The crack propagation resistance also becomes weaker under the elevated temperature than under room temperature.
