INFLUENCE OF POWDER SIZE DISTRIBUTIONS ON MICROSTRUCTURAL FEATURES OF FINELY STRUCTURED PLASMA SPRAYED COATINGS

This paper is devoted to the production of finely structured ceramic coatings by Suspension Plasma Spraying (SPS). It mainly consists in injecting in a Direct Current (D.C.) plasma jet a suspension containing submicronic ceramic particles. The presented work is aimed at producing yttria stabilized zirconia (YSZ) electrolytes of Solid Oxide Fuel Cells (SOFC). First, the effect of powder size distributions on the flattening of collected splats is studied. Second, the influence of these powder size distributions on the microstructural features of coatings is highlighted. It is shown that a narrow powder size distribution centred on about 1 μm should be used to produce coatings with a reduced porosity.