Measured and Predicted Thermal Conductivities for YSZ Layers: Application of Different Models

Abstract

Thin yttria-stabilized zirconia (YSZ) coatings were deposited on stainless steel substrates from liquid feedstocks by plasma spray technology. The porosity of the coating has a substantial effect on its thermal properties depending on the morphology and the orientation of the pores. Properties of four different YSZ layers (“cauliflower-like†and dense) were measured by the laser flash diffusivity method from RT to 800 ºC. Different analytical models for the thermal conductivity were applied and compared for the purpose of validation for thermal barrier coatings (TBCs) prepared by hybrid water-stabilized plasma spraying torch (WSP-H). Additionally, the influence of the substrate thickness, thermal stability of the coating and atmosphere during the measurement was carefully investigated. Afterwards, the models for prediction of the thermal conductivity values were applied.