Finite element analysis of the effect of thermal cycles and ageing on the interface delamination of plasma sprayed thermal barrier coatings

The present study provides a numerical simulation of the interface crack development in thermal barrier coatings, deposited using plasma spray method. The proposed model benefited from the SEM image obtained from our previous experimental studies so that the geometry was placed in a model with the dimensions of the tested specimens. In this study, the longitudinal and lateral growth effects of TGO, the creep effect of all coating layers, and the effect of thermal mismatch between layers were investigated on the stress distribution of the coating. The results obtained from previous experimental observations revealed that the separation occurs in the TC/TGO interface. Therefore, in the numerical study, it was defined as the cohesive layer. The separation of cohesive layer in various thermal ageing periods was further explored alongside the cooling-heating thermal cycles. The results obtained by the finite element analysis indicated that as the thermal ageing period increased, the interface separation was enlarged and cracks started to nucleate from other points of the interface. Separation behavior of TC/TGO interface was evaluated once increasing ageing period and thermal cycles.