Thermo-mechanical fatigue evaluation of a thermal barrier coating bond-coatless system

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:756

Article

Kromer, R.^1,3  Mauget, F.²  Despres, L.^1,2  Costil, S.¹  Cormier, J.² 

[1] Univ Bourgogne Franche Comte, ICB LERMPS UMR 6303, UTBM, F-90010 Belfort, France

[2] ISAE ENSMA, Inst Pprime, Dept Phys & Mecan Mat, CNRS,UPR 3346, Teleport 2,1 Ave Clement ADER,BP 40109, F-86961 Futuroscope, France

[3] Univ Bordeaux, Inst I2M, Bordeaux, France

关键词: Thermal barrier coating;    Superalloy;    gamma '-rafting;    Thermo-mechanical fatigue;    Thermal-overaging;   

DOI  :  10.1016/j.msea.2019.04.020

来源: Elsevier

【 摘 要 】

Thermal barrier coating systems are often subjected to complex thermo-mechanical loading involving a combination of mechanical stresses under complex thermal gradients, in addition to the contribution of oxidation to the damage processes. Recently, a thermal-barrier coating bond-coatless system has been developed using prior surface treatments. Atmospheric plasma spray (APS) Yttria-Stabilized-Zirconia (YSZ) is deposited on the AM1 nickel-based single crystalline superalloy substrate. The substrate has been either grit-blasted or laser textured before thermal spraying. The durability of these systems are investigated performing out-of-phase load controlled thermo-mechanical fatigue (TMF) tests in the 500-1100 degrees C and 120-700 MPa temperature and stress ranges. The contribution of a prior thermal over-aging of 200 hat 1100 degrees C has also been investigated. The damage mechanisms during out-of-phase TMF of the different TBC bond-coat-less systems have been studied and compared to the ones obtained during isothermal creep at 1100 degrees C/120 MPa. It is shown that a prior thermal over-aging favors cycling ratcheting during TMF cycling due to the degradation of the substrate microstructure. In addition, the coating damage mechanisms are observed to depend on the prior-surface treatment and thermal over-aging. Cracks perpendicular to the interface in the top coat have been observed whatever the specimens and microstructural state. Top coats are debonded for grit-blasted substrates while crack bifurcation above key holes is observed for laser textured substrates, leading to a better top coat TMF durability.

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