Suspension plasma sprayed (SPS) coatings can be produced with fine powder particles and tailor-made porosity.This allows to achieve low thermal conductivity which makes the coatings attractive as e.g. topcoats in thermalbarrier coatings (TBCs). Used in gas turbine applications, the TBCs are exposed to high temperatures which leadsto alterations of the microstructure. To obtain coatings with optimized properties, possible microstructurealterations like closing of pores and opening of cracks have to be taken into account. Hence, in this study, TBCtopcoats consisting of 8 wt.% yttria-stabilized zirconia (YSZ) were heat treated in air at 1150\ub0C and thereafterinvestigated using scanning electron microscopy, X-ray diffraction, and nuclear magnetic resonance (NMR)cryoporometry. For all investigated samples, the porosity decreased as a result of the heat treatment. The finerpores and cracks disappeared and the larger pores grew slightly and achieved a more distinct shape as thematerial seemed to become more compact
