An oil-impregnated porous polyimide (PI) retainer is used in space rolling bearings to improve the lubrication performance, which depends on the release of lubricant from the pores, and therefore is closely related to the pore size. To study the effect of pore size, in this work, PI materials with different pore sizes were prepared by preheating the retainer tube billet during the limit pressing process, and then the friction tests were conducted with the ball-on-ring mode. The results show that the applied load deforms the pores, allowing the lubricant to be squeezed out from the pore; the centrifugal effect induced by rotation also makes the lubricant migrate out of the pore. Therefore, for the same pore sizes, the friction coefficients decrease with the increasing loads and rotation speeds. In addition, it was found that there exists an optimal pore size for the best lubrication properties of porous PI material. Furthermore, the optimal pore size should be larger for lubricants with high viscosity. The microscopic mechanism for lubricant outflow from pores is clarified by molecular dynamic simulations. The insights gained in this study can guide the preparation of oil-impregnated porous retainers under different working conditions.

含油多孔聚酰亚胺（PI）保持器用于空间滚动轴承以改善润滑性能，这取决于润滑剂从孔隙中的释放，因此与孔径密切相关。为了研究孔径的影响，在这项工作中，通过在极限压制过程中预热保持管坯来制备具有不同孔径的PI材料，然后用球环模式进行摩擦试验。结果表明，施加的载荷使孔隙变形，使润滑剂从孔隙中挤出；旋转引起的离心作用也使润滑剂从孔隙中迁移出来。因此，对于相同的孔径，摩擦系数随着载荷和转速的增加而减小。此外，结果发现，对于多孔 PI 材料的最佳润滑性能，存在一个最佳孔径。此外，对于高粘度的润滑剂，最佳孔径应该更大。通过分子动力学模拟阐明了润滑剂从孔隙流出的微观机制。在这项研究中获得的见解可以指导在不同工作条件下制备油浸多孔固定器。