In situ SANS study of pore microstructure in YSZ thermal barrier coatings Original Research Article

Air plasma sprayed yttria stabilised zirconia (YSZ) thermal barrier coatings (TBCs) were investigated by means of SANS. The measurements were performed in situ at different temperatures up to 1200 °C and ex situ after annealing at 1200 °C up to 100 h. Scattering curves were described by three populations of pores. The parameters of nanometric and medium-sized (20 nm) pores were determined. Specimens produced under different spray parameters showed qualitatively similar behaviour of nanometric and medium-sized pores during thermal exposure at elevated temperatures. The population of nanopores increased strongly at about 800 °C. The evolution of volume and size of nanopores and medium-size pores at 1200 °C indicated their sintering. The elimination of these pores coincides with the increase of Youngʹs modulus.