Preparation of nanostructured YSZ granules by the spray drying method

The suspensions of nanosized YSZ powder with different binder (polyvinyl alcohol, PVA) contents were agglomerated into plasma sprayable feedstocks. The agglomeration was performed by the spray drying method. Two types of morphologies (spherical and non-spherical) were obtained after spray drying of the ball milled and non-ball milled nanopowders. The suitable granules size distributions (25–150µm, average size=45±3µm) with good apparent density (before calcination treatment=800kg/m3 and after calcination=900kg/m3) and flowability (before calcination=0.31g/s and after calcination=0.41g/s) for plasma spraying were obtained with 5wt% PVA and calcination temperature up to 800°C. Finally, the correlation between the granules shape and the resulting coating porosity and thermal insulation capability was investigated.