Evaluation of the long-term adhesion properties of thermal barrier coatings reinforced with SiC-ZrB2 particles under thermal cycling conditions.

This paper presents the results of the adhesion resistance before and after cyclic thermal treatments in NiCoCrAlY bond-coat (BC) coatings reinforced with dispersed SiC-ZrB 2 particles and conventional NiCoCrAlY. The ASTM-C-633 standard test method for the adhesion or cohesion strength of thermal spray coatings was used. The microstructure and morphology of the coatings were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Microhardness and coefficient of thermal expansion were also measured. The addition of SiC-ZrB 2 particles improved the long-term adhesion resistance by 1825 % compared to the system without reinforcement after 275 cycles. This improvement is attributed firstly to a self-healing mechanism and secondly to the lower thermal expansion coefficient (32.60 % lower) of the BC layer reinforced with SiC-ZrB 2 , which delayed the formation of cracks at earlier stages associated with CTE mismatch. [ABSTRACT FROM AUTHOR]