Thermophysical Properties of Air Plasma Sprayed Zirconia Coating Deposited by Reconstituted Nanosize Particles

ZrO2-3mol% Y2O3 coating was deposited by air plasma spraying using reconstituted nanosize particles. The microstructure was examined by SEM and TEM. The thermal conductivity was calculated based on the specific heat and thermal diffusivity detected by DSC and laser flash method. The results show that the thermal barrier zirconia coating with thermal conductivity ranging from 0.63-0.80 W/(m·K) is obtained. This can be attributed to the homogeneous distribution of micro-size pores and amounts of micro-cracks with average length of about 10 μm, to which heat flow is nearly perpendicular. The phase transition of t to m can result in the change of thermophysical properties. The grain growth and the decrease of porosity lead to increase of thermal conductiviy of as-sprayed coating.