Electron microscopy and diffraction studies of suspension-plasma-sprayed ZrO2 + 8 wt.% Y2O3 coatings

The microstructure of ZrO2 + 8 wt.% Y2O3 coatings has been studied by means of transmission electron microscopy (TEM) including selected-area electron diffraction (SAED) and electron backscatter diffraction (EBSD). The coatings were suspension-plasma-sprayed onto stainless steel substrates. The parameters spray distance and torch scan speed had been varied. Both diffraction methods have confirmed the tetragonal lattice structure of the suspension-plasma-sprayed zirconia. The combination of TEM and EBSD allowed a detailed analysis of the size, shape and orientation of grains. The microstructure of the coatings is mainly lamellar, consisting of columnar grains. Additional microstructural features indicate that powder particles have been subjected to different modifications during spraying. The influence of the variation of spraying parameters on the microstructure is marginal.