Structure-Processing-Property Relationships of Suspension Sprayed 7 Wt.% Y2O3-ZrO2

Suspension plasma spraying (SPS) permits coatings to be produced from sub-micron and nano-scale diameter ceramic particles, a capability which is not possible with the related technique of air plasma spraying (APS).  SPS also has the capacity to produce microstructures which are unique from yttria-stabilized zirconia (YSZ) APS coatings, including the formation of columns that eminate from the substrate. The experimental spray parameters controlling the development of these unique microstructures will be discussed.  The porosity within SPS YSZ coatings was characterized using small angle X-ray scattering on samples in the as-deposited condition and following a 50-hr, 1200°C heat treatment.  The relationships between these results and the different processing conditions will be presented, along with a comparison to similar porosity data from APS YSZ coatings.  Lastly, the microstructural information will be connected to the thermal conductivities of the SPS coatings.