Spray-drying of ceramics for plasma-spray coating

The spray-drying process of ceramics which are candidate materials for ther mal barrier coatings (TBCs), i.e. 3YSZ + 0, 2, 4, 6 wt.% Al2O3, is discusse d in this paper. The two most important properties of spray-dried powders t o determine the coating quality are density and particle size. Polyethylene imine (PEI) acts as both an organic binder and a dispersant giving low visc osity in the suspension. The optimised suspension composition is: greater t han or equal to 33.6 vol.% powder + 1.8 wt.% PEI + ethanol, and operational parameters of the spray-dryer: drying temperature 175 degreesC, feeding ra te 55 cm(3)/min, feeding pressure 1.013 x 10(4) Pa. (C) 2000 Published by E lsevier Science Ltd. All rights reserved.