Evolution of thermal conductivity of dysprosia stabilised thermal barrier coating systems during heat treatment

Dysprosia stabilised zirconia coatings offer a potential reduction in thermal heat transfer for thermal barrier coating systems with the added benefit of being producible with existing equipment and spray knowledge. However, there is little information on the long term performance of such systems relative to the standard coatings. Whilst a low thermal conductivity is important for a gas turbine; sintering resistance is important to maintain properties over the lifetime of a component.In this study, four dysprosia stabilised zirconia coatings are compared with a standard yttria stabilised coating in present industrial use.Samples were exposed to isothermal furnace conditions at 1150 °C from 5 to 200 h to observe the sintering resistance of the coating systems. Tests carried out include microstructural analysis with SEM, thermal conductivity measurements using laser flash analysis and porosity changes monitored using image analysis.

► Thermal barrier coatings based on dysprosia stabilised zirconia were produced.
► Thermal properties and microstructure were characterised after heat treatment.
► Thermal conductivity of the dysprosia coatings is lower than standard yttria coatings.
► High purity DySZ coatings show greater sintering resistance than standard YSZ.