Fabrication of Porous YSZ for High Temperature Abradable Coating Application by Flame Spraying

High performance gas turbine requires application of high temperature ceramic abradable coating at high temperature turbine sectors. In this study, porous YSZ coating deposition was attempted directly through deposition of surface-melted spray particles by flame spraying to develop the novel method to fabricate ceramic abradable coating. The commercially available YSZ powders were spheriodized by plasma jet and screened to a limited particle size range for control of spray particle melting state. YSZ coatings were deposited at different flame powers and spray distances. The porosity of the coating was estimated by image analyzing from the cross section. The results showed that porous YSZ coating with a porosity level of up to 60% can be successfully deposited by controlling particle melting degree. The influence of spray particle melting degree, depending on spray distance and flame power, on coating microstructure and porosity was examined for the optimization of porous coating microstructure.