Thermal conductivity imaging of thermal barrier coatings

The use of time-domain thermoreflectance (TDTR) method at a fixed delay time to image the thermal conductivity of the cross-section of thermal barrier coatings with micron-scale resolution was described. The method is used to measure the thermal conductivity of amorphous SiO ₂, single crystal 8 wt% YSZ, and a NiCr alloy. The thermal conductivity of the as-deposited yttria-stabilized zirconia coatings is found to be 1.84±0.08 W m ^-1 K ^-1 in the in-plane direction and 1.7±0.25 W m ^-1 K ^-1 in the through-thickness direction. The in-plane thermal conductivity is found to increase to 2.2±0.0 W m ^-1 K ^-1 after 500 furnace cycles.