Structural evolution of thermal-sprayed yttria-stabilized ZrO2 thermal barrier coatings with annealing - A neutron diffraction study

We studied the influence of the annealing temperature on the atomic structu re of yttria-stabilized tetragonal zirconia (YSZ) which was deposited as a 300 mum thick thermal barrier coating (TBC) on nickel superalloy substrates by plasma spraying. To obtain neutron powder diffraction patterns of the b arrier coatings we used an experimental technique where the sample is rando mly rotated in the neutron beam. The time-averaged neutron diffraction patt ern was then analyzed using the Rietveld refinement technique without any n eed for corrections. This allowed the comparison of the average crystals st ructures from bulk tetragonal samples obtained via common ceramic routes an d those of micrometer thick films deposited on substrates using plasma spra y or other nonequilibrium techniques.