Spray drying of nanometric SYSZ powders to obtain plasma sprayable nanostructured granules

This study addresses the correlation between the feedstock agglomerates with their resulting coating microstructure and thermal insulation capability. To this end, the Y2O3 and Sc2O3 codoped in ZrO2 (SYSZ) nanopowders were synthesized by the polymeric sol–gel method, their suspensions were agglomerated into plasma sprayable feedstock by the spray drying method, and finally, the effect of feedstock morphology on the microstructures and thermal insulation capability of APS coatings was investigated. The coating microstructure consisted of semi-molten feedstock agglomerates surrounded by fully molten particles that acted as binders. Solid irregular SYSZ granules yielded coatings with lower porosity and thermal insulation capability than the porous spherical YSZ ones.