Development of Porous YSZ Coatings with Modified Thermal and Optical Properties by Plasma Spray Physical Vapor Deposition

Porous and feather-like yttria-stabilized zirconia coatings have been deposited by plasma spray physical vapor deposition (PS-PVD) at the deposition rate of around 200 µm/min. The porosity of the coating reached > 50% and the overall thermal conductivity was reduced less than 0.5 W/mK, both of which were fundamentally independent of the coating thickness up to 120 µm. Such coating structures were characterized by their high scattering coefficients at light wavelength from 2 to 6 µm, and thus the transmittance to infrared was reduced significantly compared to the splat structure coating with the identical thickness. The thermal properties of these coatings were retained even after annealing at temperature ∼1500°C for 130 hours.