“…More attention has been paid to oil self-lubricating material, which has good self-lubricating properties, because of its internal porous structure (Wang et al, 2014a(Wang et al, , 2014b(Wang et al, , 2013, and it is very suitable when difficulties are faced during lubricating oil supply and also for avoiding contamination (Lu and Liu, 2013;Pan et al, 2015). Of all these porous materials, polymer-based composites have attracted more attention in many fields (Huang et al, 2015;Tang et al, 2015;Chen et al, 2015). In the USA, polyimide (PI) porous material has already been used in different kinds of high-precision terminal systems, such as aircraft and inertial navigation of satellites (Blum and Ovaert, 2013).…”