Low-thermal-conductivity plasma-sprayed thermal barrier coatings with engineered microstructures

The solution precursor plasma spray (SPPS) process has been used to deposit ZrO2–7 wt.% Y2O3 thermal barrier coatings (TBCs) that contain alternate layers of low and high porosities (layered-SPPS). The thermal conductivity of the layered-SPPS coating is found to be lower than those of both a SPPS coating with distributed porosity and an air-plasma-sprayed coating of the same composition, in the temperature range 100–1000 °C. Analytical and object-oriented finite element (OOF) models have been used to analyze the experimental thermal conductivity data. The OOF model is better at describing the experimentally measured thermal conductivities than the analytical model, and the OOF model captures accurately the effect of real microstructures on the thermal conductivities of these plasma-sprayed TBCs.