Effect of microstructure on thermal cycle fatigue resistance in a SPS-TBC

Abstract

The turbine blades of gas turbine engines used in thermal power plants are coated with a thermal barrier coating (TBC) made of ceramics to provide heat resistance. In recent years, gas turbines for power generation have been utilized as a regulating power source for engines, which are subject to frequent start-up and shutdown and output fluctuations. In this context, the suspension plasma spraying (SPS) method, which has been developed recently, has been studied intensively because it has a porous columnar structure and superior thermal cycle properties compared with the conventional atmospheric plasma spraying method. In this study, we evaluated the thermal cycle properties of TBCs with different microstructures prepared by varying the deposition conditions of the SPS method, and investigated the effect of microstructures on the thermal cycle properties. The experimental results indicated that the thermal cycle fatigue life of SPS-TBC increased with decreasing column diameter. The effect of microstructure on the thermal cycle fatigue life was discussed based on the thermal stress in top-coating evaluated by the FE analysis.