ABSTRACT
Thermal barrier coatings (TBCs) are also selected as the topic of a special chapter, because of their important roles in protecting gas turbine components, as the requirement of increasing the gas turbine engine firing temperature is demanded for high power and performance. In this chapter, microstructural evolution in terms of thermally-growth oxides (TGO) and crack evolution is discussed in detail for air-plasma sprayed (APS) TBCs. A crack number density (CND) theory model is developed for crack evolution driven by the Evans-He-Hutchinson spherical wedge-cracking mechanism, which give a very good description of crack-size distribution as function of cyclic-thermal exposure time in APS-TBC, and hence it can be used for TBC life prediction. Other TBC life prediction models are also critically reviewed.
