THERMAL CONDUCTIVITY OF NANOPOROUS YSZ THERMAL BARRIER COATINGS FABRICATED BY EB-PVD

ZrO(2)-4mol% Y(2)O(3) (YSZ) coatings were deposited by EB-PVD. The YSZ coatings consist of porous-columnar structure containing nano pores and intercolumnar gaps between columnar grains. The laser flash method and differential scanning calorimeter were used to measure the thermal diffusivity and specific heat of the coated samples. The thermal conductivity of EB-PVD coatings decreased with increasing measuring temperature as well as porosity. The thermal conductivity of the coating layer alone was also calculated based on thermal diffusion results for the double layers specimens consisting of the combined coatings and substrate. The response function method was employed to obtain an accurate value for the thermal conductivity of the coatings layer. The thermal conductivity of coatings layer showed increasing tendency with increasing the coatings thickness.