Effect of high-temperature infrared emissivity on thermal cycling performance of magnetoplumbite-type thermal barrier coatings under thermal gradient condition

The study aims to investigate the influence of infrared emissivity on thermal barrier coating (TBCs) for service applications. Two double-layer TBCs, namely RMgAl11O19/YSZ (marked as RMA/YSZ, R=La, Pr) and conventional single-layer YSZ TBCs, were comparatively tested using a burner rig facility. The microstructure, infrared emissivity, and thermal cycling performance of the three TBCs were investigated. The results demonstrate that the emissivity of PrMA/YSZ has been improved by approximately 20% compared to LaMA/YSZ in the wavelength range of 2-6 mu m, owing to an improvement in electronic transition. Due to higher emissivity, the surface temperature of PrMA/YSZ decreased by 70 degrees C under the same heat flux, leading to a reduction in coating aging and substrate temperature. Accordingly, PrMA/YSZ exhibited the highest thermal cycling lifetime among the three coatings.