Direct observations of erosion-induced ferroelasticity in EB-PVD thermal barrier coatings

Imaging of the presence and location of erosion-induced ferroelastic toughening was completed on 8-weight percent yttria-stabilized zirconia EB-PVD thermal barrier coatings using confocal polarized Raman spectroscopy. A combination of measurements made using ultraviolet and visible laser radiation was conducted to determine the location and extent of ferroelastic twinning present at and below the eroded surfaces as well as along fracture surfaces of the coatings. Ferroelastic twinning events were identified at three major locations within and on the coating: the erosion surface, just below the surface, and in the bulk of the coating. The results shown here reveal that not all fracture events result in a ferroelastic response. This suggests there may be an opportunity to increase the toughness of thermal barrier coatings by increasing the possibility that a crack can produce a ferroelastic twin in the coating.