In this study, agglomerated nanocrystalline ZrO2--Y2O3 powder was calcinated from 900 to 1300 °C for 2 h. The calcinated nanopowder was used as feedstock and deposited by air plasma spraying on a NiCoCr bond coat applied to a nickel substrate via low pressure plasma spraying. For comparison, conventional ZrO2-Y2O3 topcoats were also produced. Nanostructured and conventional thermal barrier coatings were calcinated from 1050 to 1250 °C for 2-20 h. Experimental results indicate that monoclinic tetragonal phases in the agglomerated nanopowder were transformed into cubic phase after calcination. The cubic phase content increased with increasing calcination temperature. High temperature calcination can make the yttria segregated at grain boundaries dissolve in zirconia. Different from the phase constituent of the as-sprayed conventional TBC, which consisted of diffusionless transformed tetragonal, the as-sprayed nanostructured TBC consisted of cubic phase containing high yttria. No phase transformations were observed in either TBC after calcination.

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