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Abstract: With the aid of three-point bending test the mechanical behavior of the NiCrAlY coating systems with or without barrier layer was analyzed. Together with the results from tensile adhesion test the damage mechanism of the investigated systems was discussed. It is found that the damage behavior was mainly dependent on the interfacial adhesion and the overlayer property. With a strong or weak interfacial adhesion and the brittle or ductile overlayer different damage mechanism was developed during test. The presence of residual stress and brittle precipitates or flaws at the coating/substrate interface influenced the interfacial adhesion property. The thermal exposure treatment improved the interfacial strength and the overlayer ductility. [Copyright &y& Elsevier]

Abstract: The microstructural evolution of the NiCrAlY/CrON system during vacuum heat treatment and thermal exposure was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The elastic modulus and residual stress of the coating system were measured by nanoindentation and photo-stimulated luminescence spectrum (PSLS) methods, respectively. It was shown that the series reaction of β→γ′→γ took place in the NiCrAlY coating, which contributed to a decrease in the Young’s modulus. The replacement of Cr2O3 by Al2O3 during thermal exposure resulted in an increase of the Young’s modulus of the barrier layer. A change in the residual stress in the barrier layer was due to a combination of thermal and growth stresses. [Copyright &y& Elsevier]