Delamination buckling and spalling of plasma-sprayed thermal barrier coatings

The delamination buckling and spalling of plasma-sprayed thermal barrier coatings is modelled using basic concepts from fracture mechanics and the theory of crack propagation. An upper bound for the maximal allowable thickness of a coating is derived which takes into account the fracture toughness of the coating as well as the mismatch in both thermal and mechanical properties of the coating and the substrate, the difference between the ambient temperature and the temperature at which the coating was bonded to the surface, the time required for the roll to make a complete revolution, and the number of cycles the roll is subjected to.