Abstract No.:
2663

 Title:
Isothermal oxidation behavior of NiCoCrAlTaY coating deposited by high velocity air-fuel spraying

 Authors:
Guan-Jun Yang / School of Materials Science and Engineering, Xi'an Jiaotong University, China
Xu-Dong Xiang/ DongFang Turbine Co., Ltd., China
Lu-Kuo Xing/ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, China
Ding-Jun Li/ DongFang Turbine Co., Ltd., China
Chang-Jiu Li/ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, China
Cheng-Xin Li/ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, China

 Abstract:
The performance of thermal barrier coatings is significantly influenced by the oxidation and corrosion behavior at high temperature of MCrAlY bond coat. Low pressure plasma spraying and high velocity oxy-fuel spraying are widely employed to deposit MCrAlY bond coats. In this paper, NiCoCrAlTaY bond coats were deposited by high velocity air-fuel (HVAF) spraying, and the microstructure and surface morphology of the bond coat were examined and their effects on the isothermal oxidation behavior were examined. Results show that the as-sprayed coating presents a dense microstructure and some partially melted particles in a near spherical morphology were deposited on the coating surface. A uniform ±-Al2O3 oxide scale was formed on the HVAF sprayed MCrAlY coating surface after the pre-oxidation treatment in an argon atmosphere. A small fraction of mixed oxides including NiCr2O4 was formed when the MCrAlY coating was oxidized at 1000oC for 8 hours. The amount of the mixed oxides did not significantly increase in 200 hours of oxidation. The analysis of cross-sectional microstructure reveals that the mixed oxides were formed through small splashed particles that adhered on the coating surface and did not well bond to the underlying bulk particles. Except the small amount of the mixed oxides, the ±-Al2O3 oxide scale was homogeneously grown on the surface of the bond coats in 200 hours at 1000oC in air.

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