The friction properties of oil-impregnated porous polyimide (PPI) material are closely related to surface pore size which is subject to changes during processing. Though the pores inside PPI, designed according to requirements of applications, could not be changed conveniently, surface pores are easy to be modified. To study the effects of surface pores, pores on PPI surface was enlarged by laser scanning and shrunk by spreading a thin layer of finer polyimide particles on PPI surface during molding. Oil absorption of PPI materials was tested with a U-tube test rig and a contact angle goniometer. The friction tests were carried out on a ball-on-disc tribometer. The results shows that though larger surface pores may increase oil absorption-extrusion, the friction coefficient gets higher. The friction coefficient can be decreased by shrinking surface pores. Larger surface pores make oil extrude easily but lead to low capacity of oil film, vice versa. Therefore, a balance exists between oil absorption-extrusion and the capacity of oil film by fabricating proper surface pore size. In this paper, the oil-impregnated friction coefficient is reduced by 18.8 % through spreading finer powder filtered by 400 mesh on PPI material surface.

油浸多孔聚酰亚胺（PPI）材料的摩擦性能与表面孔径密切相关，在加工过程中会发生变化。PPI内部的孔隙是根据应用要求设计的，虽然不能方便地改变，但表面孔隙很容易被修饰。为了研究表面孔隙的影响，通过激光扫描扩大 PPI 表面的孔隙，并在成型过程中通过在 PPI 表面散布一层较细的聚酰亚胺颗粒来缩小孔隙。PPI 材料的吸油性使用 U 型管试验台和接触角测角仪进行测试。摩擦试验在球盘摩擦计上进行。结果表明，虽然较大的表面孔隙可能会增加吸油挤出，但摩擦系数会变高。可以通过收缩表面孔隙来降低摩擦系数。较大的表面孔隙使油容易挤出，但导致油膜容量低，反之亦然。因此，通过制造适当的表面孔径，在吸油-挤出和油膜容量之间存在平衡。本文通过在PPI材料表面撒上400目过滤的细粉，使含油摩擦系数降低18.8%。