6533b7d8fe1ef96bd126a0c3

RESEARCH PRODUCT

Comportement en fatigue thermomécanique à haute température d’un système barrière thermique texturé par laser

subject

description

In service life of Thermal Barrier Coating (TBC) systems for blade applications can be limited by the top-coat (TC) spallation under thermo-mechanical fatigue (TMF) loadings. To improve its TMF life, laser texturing at the bond-coat/top coat interface in the CMSX-4 Plus / γ-γ’ BC/ EB-PVD TC system has been investigated.Thanks to the study of the laser-matter interaction, it seems that the different Ni-based single crystal superalloys have similar laser ablation behaviors and they present almost no sub-surface damage after ablation. Nevertheless, the formation of melted matter near created cavities, possibly recrystallized, is often observed.Different patterns (holes, lines, grids) have been developed at the BC surface, in order to increase the mechanical anchoring without modifying the TC microstructure. To discriminate the surface morphologies by the evaluation of the spallation lifetime of textured TBC systems, 1150°C thermal cycling tests have been carried out. Furthermore, to validate the developed technological solution, thermal gradient mechanical fatigue (TGMF) tests in engine simulated environment have been performed using samples with and without textured surfaces (MAATRE test bench). The results shows that laser textured patterns slow down the spallation of the TC, without promoting crack initiation.