多孔聚酰亚胺含油轴承保持架的磨损机理研究

On Wear Mechanism of Porous Polyimide Oil-containing Bearing Cage

在实际运转过程中,空间含油轴承保持架在兜孔、引导面上均表现出不同程度的磨损发黑现象,认清其磨损机理对于指导含油材料设计、提升空间轴承性能至关重要.采用冷压热烧结的方法制备了多孔聚酰亚胺(PPI)材料,通过打磨处理改变PPI表面形态,继而研究了表面形态对其摩擦磨损及摩擦界面输供油性能的影响,并在此基础上提出了含油材料的磨损模型.结果表明,PPI材料的磨损发黑源于孔隙边缘的微区承载,在高压载荷作用下孔隙边缘会发生剪切变形、断裂,产生的摩擦热会诱发聚酰亚胺材料或润滑油的分解和碳化.含油保持架的磨损会对轴承持续运转产生影响,孔隙边缘发生的剪切变形以及产生的磨屑会封堵保持架表面孔隙,破坏摩擦界面输供油路径,导致摩擦系数的波动和磨损的持续变大,对轴承的运转稳定性和摩擦噪音产生潜在的负面影响.

In the actual operation process,the space oil-bearing cage exhibits different degrees of wear and blackening on the pockets and guide surfaces,and it is important to recognize the wear mechanism so as to guide the design of oil-containing materials and improve the performance of space bearings. In this paper,porous polyimide (PPI) material is prepared by cold pressing and hot sintering. The morphology of PPI is changed by grinding treatment,and then the influences of surface morphology on friction and wear and oil supply performance of friction interface are studied. Finally,possible wear model of oil-containing materials is addressed. The results show that the blackening of the PPI material is caused by the micro-region bearing at the edge of the pore. Under the high-pressure load,shear deformation and fracture occur at the edge of the pore. The frictional heat generated will induce the decomposition of the polyimide material or lubricating oil. The wear of the oil-containing cage can affect the operation of the bearing. The shear deformation at the edge of the hole and the generated grinding debris can block the pores on the surface of the cage and destroy the oil supply path of the friction interface,resulting in fluctuation of friction coefficient and increasing of wear volume,and has a potential negative impact on the running stability of the bearing and the friction noise.