High-temperature cyclic oxidation behavior of Al2O3–YAG composite coating prepared by EPD and microwave sintering

Abstract Al2O3–YAG (Y3Al5O12) composite coatings were successfully fabricated on NiCoCrAlY alloy substrates by electrophoretic deposition (EPD) in Y3+ doped composite sol–gel suspensions and pressure filtration microwave sintering (PFMS). The composite coating was dense, crack-free and had good adherence with substrate even after cycling oxidation at 1000 °C for 200 h. Filed emission SEM showed that nano-size YAG particles were embedded in α-Al2O3 matrix. The high-temperature cyclic oxidation tests revealed that the oxidation resistance and spallation resistance were greatly improved. The oxidation resistance of alloy is mainly determined by α-Al2O3 sealing effect and reactive elements effects (REE) on the thermally grown oxide (TGO) scale. Moreover, the enhanced fracture toughness and strength of this composite coating can be attributed to the nano/submicro composite structure and YAG particles toughening effects.