Oil-impregnated porous polyimide (iPPI) materials are usually used as retainer for bearings. In these bearings, balls and rings, balls and retainers are two different kinds of contact. In this paper, the friction and wear properties of iPPI were investigated using steel (disc)—steel (ball)—iPPI (pin) double-contact friction test rig for simulating the actual contact in bearings. The results show that compared with that of iPPI—steel single contact, the friction coefficient of iPPI—steel in double contacts is lower and decreases with the amount of additional oil. The surface of iPPI in single contact suffers more wear compared with that in double contacts. Different from single contact, the worn surfaces of iPPI in double contacts are blackened. The Raman spectra of worn surfaces of balls and discs indicate that α-Fe₂O₃ and Fe₃O₄ were formed during rubbing of the double contacts. Many nanoscale iron oxide particles are found on the worn surfaces of iPPI in double contacts; on the contrary, few particles could be found on the surface in single contact. In double-contact friction, the nanoscale wear debris penetrates inside the iPPI material through the process of extruding and recycling of oil, which is the mechanism of the blackening of the iPPI worn surfaces. The studies show that the double-contact friction method is a new and effective method to study the friction in bearings, especially for those with polymer retainer.

油浸多孔聚酰亚胺 (iPPI) 材料通常用作轴承的保持器。在这些轴承中，滚珠和套圈、滚珠和保持器是两种不同的接触方式。本文采用钢（盘）—钢（球）—iPPI（销）双接触摩擦试验台模拟轴承中的实际接触，研究了iPPI的摩擦磨损性能。结果表明，与iPPI-钢单触头相比，iPPI-钢双触头的摩擦系数较低，且随着加油量的增加而减小。与双触点相比，单触点iPPI表面磨损更大。与单触点不同，双触点iPPI的磨损面是发黑的。球和盘磨损表面的拉曼光谱表明α-Fe ₂O ₃和Fe ₃ O ₄在双触点的摩擦过程中形成。在双触点的 iPPI 磨损表面发现许多纳米级氧化铁颗粒；相反，在单次接触的表面上几乎没有发现颗粒。在双接触摩擦中，纳米级磨屑通过油的挤压和循环过程渗入iPPI材料内部，这就是iPPI磨损表面黑化的机理。研究表明，双接触摩擦法是研究轴承摩擦的一种新的有效方法，特别是对于带有聚合物保持器的轴承。