镍基耐高温自润滑刷式封严涂层研究

为满足先进航空发动机刷式封严对涂层材料自润滑耐磨性能的要求,采用等离子喷涂技术制备了NiCoCrAlY-Cr_2O_3和NiCoCrAlY-Cr_2O_3-AgMo两种复合涂层;采用扫描电子显微镜、X射线衍射、拉曼光谱和高温摩擦磨损试验等分析测试手段研究了涂层的物相组成、微观结构、力学性能以及摩擦磨损性能。结果表明:研制的两种新型涂层具有较低的孔隙率、较高的显微硬度和结合强度,从20℃到800℃的磨损量都在10~(-5)mm~3·N~(-1)·m~(-1)数量级,显示出优异的耐磨性能;NiCoCrAlY-Cr_2O_3涂层在摩擦系数随着温度的升高而降低,在800℃达到最低值0.3;NiCoCrAlY-Cr_2O_3-AgMo涂层从400~800℃的摩擦系数一直保持在0.23左右。对其摩擦机理的研究表明:400℃时涂层与高温合金GH4145对磨件之间形成连续的含Ag润滑膜,600℃以上时摩擦表面生成的Ag_2MoO_4自润滑相显著降低了涂层的摩擦和磨损。

Investigation of Ni-Based Brush Seal Coatings With Self-Lubricating Property at Elevated Temperature

In order to meet the requirement of self-lubricating and wear resistant properties of brush seal coatings for advanced aeroengines,two kinds of novel composite coatings,NiCoCrA1Y-Cr2O3 and NiCoCrA1Y-Cr2O3-AgMo,were prepared with plasma spray technology.Microstructures,phase compositions,mechanical properties,friction and wear performances of the above coatings were characterized and analyzed with scanning electron microscopy (SEM),X-ray diffraction (XRD),Raman spectroscopy and CSM high-temperature tribometer.The results show that both coatings exhibit very low porosity,high microhardness and tensile strength.The wear rates of two coatings are all at the order of 10-5 mm3.N-1·m~,indicating the excellent wear resistance.The friction coefficient of the coating NiCoCrAlY-Cr2O3 decreases with temperature increasing,which shows a minimum value of 0.3 at 800℃.NiCoCrAlY-Cr2O3-AgMo coating keeps a lower friction coefficient of about 0.23 from 400℃ to 800℃.Investigation of friction and wear mechanisms show that at 400℃,a lubricating film containing Ag is formed between the coating and the counterpart,while Ag2MoO4 formed above 600℃ effectively reduces the friction and wear at high temperatures.