目的 研究等离子喷涂 NiCoCrAlY/ Al2O3 高温固体润滑耐磨涂层在 850 ℃时的高温抗氧化性能和抗氧化机理。 方法 采用喷雾造粒、化工冶金包覆技术制备 NiCoCrAlY/ Al2O3 复合粉体,并采用等离子喷涂技术在 45#钢表面制备 NiCoCrAlY/ Al2O3 复合涂层。 采用 SEM 和 XRD 研究粉体和涂层的显微结构和物相组成,并采用马弗炉研究复合涂层在 850 ℃的恒温氧化动力学曲线,通过研究氧化 96 h 以后涂层表面的组织形貌,探讨 NiCoCrAlY/ Al2O3 复合涂层的抗氧化机理。 结果 NiCoCrAlY 合金层均匀致密地包覆在 Al2O3 颗粒的表面,包覆层厚度约为 3 ~ 5 μm。 复合粉体的主要组成为 Al2O3 相和 NiCoCrAlY合金相,没有其他杂质相的存在。 等离子喷涂 NiCoCrAlY/ Al2O3 复合涂层氧化动力学曲线分为大斜率直线、抛物线和系数几乎为 0 的抛物线等 3 个阶段。 氧化 96 h 以后,涂层的氧化质量增量为 4. 9 mg/ cm2 左右,表面形成了一层连续的氧化物保护膜,经 EDX 分析,氧化膜层主要由 Al,O,Cr 和 Ni 组成。 结论 等离子喷涂 NiCoCrAlY/ Al2O3 复合涂层具有良好的高温抗氧化性能,涂层中 Ni,Cr,Al 的氧化以及硬质相Al2O3 的加入是涂层抗氧化的主要原因。

Objective To study the oxidation resistance and oxidation-resistance mechanism of atmospheric plasma-sprayed NiC- oCrAlY / Al2 O3 wear-resistant coatings at 850 ℃ . Methods The NiCoCrAlY / Al2 O3 composite powder was prepared by the technolo- gy of spray granulation, chemical and metallurgical coating and solid state alloying. The NiCoCrAlY / Al2 O3 composite coating was prepared by atmospheric plasma-spray technology using the prepared powder on the surface of 45# steel. The microstructure and phase composition of the powder and coating were studied by SEM and XED. The oxidation kinetic curve at constant 850 ℃ was explored with muffle furnace and the oxidation resistance mechanism of the APS sprayed NiCoCrAlY / Al2 O3 composite coatings was investigated through analysis of morphology of the coating surface after 96 h of oxidation. Results The Al2 O3 was evenly and closely coated with NiCoCrAlY alloy and the thickness of NiCoCrAlY alloy was 3 ~ 5 μm. The phase compositions of composite powder were mainly NiCoCrAlY and Al2 O3 without other impurities. The oxidation kinetics curves of the coatings can be divided into three stages: severely sloping, parabolic and slightly parabolic stages. The value of oxidation weight gain was about 4. 9 mg / cm2 after 96 h of oxidation. The oxide film was formed and the phase compositions of oxide film were Al,O, Cr and Ni according to the EDX a- nalysis. Conclusion The NiCoCrAlY / Al2 O3 composite coating exhibited excellent oxidation resistance property. The reason of oxi- dation resistance of the coating was the oxidation of Ni, Al and the addition of Al2 O3 .