Preparation and characteristics of three-layer YSZ–(YSZ/Al2O3)–YSZ TBCs

Novel three-layer YSZ–(YSZ/Al2O3)–YSZ (6 wt.% Y2O3 partially stabilized ZrO2) thermal barrier coatings (TBCs) were successfully prepared on Ni-based superalloy substrate using composite sol–gel and pressure filtration microwave sintering (PFMS) techniques. The coatings were evaluated for the cyclic oxidation resistance, thermal barrier effect and the presences of phases and microstructures. FE-SEM results indicate that the coatings were dense and crack-free. The coatings maintained their structural integrity when they were exposed at 1100 for 100 h. They exhibited superior oxidation resistance, spallation resistance and thermal insulation property compared with single-layer YSZ coatings. Moreover, the detailed mechanisms were discussed in order to understand the improved performance of the three-layer TBCs.