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采用喷雾造粒、化学冶金包覆和固相合金化技术制备了Ni Co Cr Al Y/Al2O3复合粉体,并采用超音速火焰喷涂技术制备了Ni Co Cr Al Y/Al2O3复合涂层。采用SEM、XRD和马弗炉对该涂层和粉体的显微结构和抗氧化性能进行了研究。结果表明,Al2O3颗粒表面均匀致密的包覆着一层Ni Co Cr Al Y合金,Ni Co Cr Al Y/Al2O3复合粉体呈球形,颗粒大小均匀。超音速火焰喷涂Ni Co Cr Al Y/Al2O3复合涂层与基体结合良好,涂层孔隙率仅为(0.41±0.05)%。涂层抗氧化性能良好,氧化动力学曲线分为3个阶段:大斜率直线阶段,系数较小的抛物线阶段和斜率几乎为零的直线阶段。涂层在850℃氧化96 h以后,涂层氧化增重为2.5 mg·cm-2左右。复合涂层中氧化物膜的形成和Al2O3硬质相的加入是涂层抗氧化性能提高的主要原因。
Ni Co Cr Al Y / Al 2 O 3 composite powders were prepared by spray granulation, chemical metallurgy coating and solid-phase alloying. Ni Co Cr Al Y / Al 2 O 3 composite coatings were prepared by supersonic flame spraying. The microstructure and oxidation resistance of the coatings and powders were investigated by SEM, XRD and muffle furnace. The results show that the surface of Al2O3 particles is uniformly and densely coated with a layer of Ni Co Cr Al Y alloy. The Ni Co Cr Al Y / Al 2 O 3 composite powders are spherical with uniform particle size. The supersaturated flame sprayed Ni Co Cr Al Y / Al 2 O 3 composite coating was well bonded with the matrix, and the porosity of the coating was only (0.41 ± 0.05)%. The oxidation resistance of the coating is good. The oxidation kinetics curve is divided into three stages: the large slope straight-line phase, the small coefficient parabola phase and the almost zero straight-line slope phase. After oxidation of the coating at 850 ℃ for 96 h, the weight gain of the coating is about 2.5 mg · cm-2. The formation of oxide film and the addition of Al2O3 hard phase in the composite coating are the main reasons for the improvement of the oxidation resistance of the coating.