Thermal conductivity of EB-PVD ZrO₂-4 mol% Y₂O ₃ films using the laser flash method

The variation in thermal conductivity and thermal diffusivity of ZrO ₂-4 mol% Y₂O₃ coatings deposited onto Inconel substrates by EB-PVD is examined as a function of coating thickness using the laser flash method. The coatings are found to consist of columnar grains with a feather-like microstructure. The thermal conductivities of the coatings are calculated using two methods: the first involves separating the coating from the substrate and measuring the thermal diffusivity directly; the second uses thermal diffusion results from coatings still attached to the substrate and is based on the response function method. The results of both methods are in excellent agreement, and show that the thermal conductivities of the coatings increase with increasing coating thickness. The results also confirm that the double layer method can be used successfully to calculate the thermal conductivities of thin film coatings.