Thermal Property Measurements of YSZ-Al2O3 Ceramic Composites

Thermal barrier coatings (TBCs) are used in gas turbine engines to achieve a higher working temperature, and thus lead to a better efficiency Yttria-stabilized-zirconia (YSZ), a material with low thermal conductivity, is commonly used as the top coat layer to provide the thermal barrier effect. Recent studies demonstrated that YSZ-Al2O3 composite layer could reduce the oxygen diffusion through the TBC, thus YSZ-Al2O3 composite layer potentially could be used to mitigate the spalling induced failure of a TBC coating. The goal of this study is to investigate the effect of the addition of Al2O3 on the thermal properties of YSZ based TBCs. In this study, a stainless steel die was used to make disk shaped samples with 0, 1, 2, 3, 4 and 5 wt% Al2O3 /YSZ powder ratios under uniaxial pressure. A laser flash system was used to measure the thermal diffusivity for all samples and the porosity of the samples is measured using mercury porosimetry. It is found that adding Al2O3 to YSZ decreases the thermal conductivity and increases the porosity of the ceramic composites.