An experimental investigation on thermo-mechanical buckling delamination failure characteristic of air plasma sprayed thermal barrier coatings

Abstract

The primary intention of this work is to investigate the thermo-mechanical buckling delamination failure characteristic of air plasma sprayed thermal barrier coatings (TBCs) under compression tests at high temperature. The TBCs samples with a pre-delamination were firstly designed and they had been successfully prepared by air plasma sprayed technique. The main novelty of this paper is that the first work to validate and obtain three kinds of the interface failure forms in TBCs system during compression tests, i.e. buckling delamination, edge delamination and global buckling failure. The effects of the initial delamination length, temperature gradient and applied mechanical load on the delamination resistance of the TBCs system were discussed in detail. It is difficult to observe buckling delamination or edge delamination failure phenomena until the initial delamination length in TBCs reaches or exceeds 4 mm or more. For edge delamination failure, the interface fracture toughness ( Γ i II), energy release rate ( G ss edge) and stress intensity factor ( K II) between the TBC/TGO interface were 35 J m − 2 , 38.8 J m − 2 and 0.97 MPa m at high temperature gradient, respectively. Using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), it was inferred that the delamination fracture located within the ceramic coating close to the TBC/TGO interface. The results agree well with other experimental and theoretical results.