Sintering characteristics of plasma-sprayed TBCs: Experimental analysis and an overall modelling

In this study, sintering behaviour of plasma-sprayed thermal barrier coatings (PS-TBCs) was investigated experimentally and theoretically. Results show that the sintering kinetics of PS-TBCs is highly stage-sensitive. The sintering proceeds significantly faster at initial short thermal exposure (<20 h), while it slows down dramatically at following long thermal exposure. A detailed examination on microstructural evolution of the PS-TBCs was carried out to understand their sintering behaviour. Results show that, different from the conventional sintering theory, the healing of 2D pores was dominantly responsible for the stage-sensitive sintering kinetics during thermal exposure. In brief, the sintering characteristics of the PS-TBCs are highly structure specific. In addition, a structural model was developed based on the structural characteristics of the PS-TBCs; and the model predicts a well consistent sintering behaviour with experiments. Finally, an outlook towards TBCs with higher performance was put forward.