During the coating preparation process

differences in the morphology

size

molten state

flight path

and spreading behavior on the substrate of the feedstock result in a certain degree of undulation within and among the adjacent coating layers. Changes in the geometry of the interface of the coatings make the morphology at the interface more complex

showing irregular and inhomogeneous structural characteristics. It also further makes the stress distribution at the interface uneven

leading to unpredictable failure of the self-healing TBCs at the interface

in the subsequent service process

which in turn leads to the warpage or delamination failure of the entire coating. Finite element software was used to simulate the effect of the variation of the surface morphology on the residual stress which is inside the coating and at the interface. By establishing the cosine ideal interface model

it is found that when the wavelength L of interface Ⅰ and interface Ⅱ increases

both the maximum S

22

tensile stress and compressive stress of interface Ⅰ and interface Ⅱ decrease. When the amplitude A of interfaces Ⅰ and Ⅱ increases

the stress is affected by both interface roughness and interface buffer stress. Varying the phase offset d between the peaks at the upper and lower interfaces

it is found that the microstructural characteristics of interface Ⅰ have a greater influence on the tensile stress at the peaks of interface Ⅱ . When the valley of interface I faces the peak of interface Ⅱ

this morphology pattern can reduce the maximum tensile stress of interface Ⅱ by 25.7% and avoid excessive stresses at interface Ⅱ. Further

the failure mechanism of the coating is systematically investigated

which provides a more comprehensive theoretical guidance for the optimal control of the interface of the self-healing thermal barrier coatings and the optimal design of the processing technology.