Characteristic parameter to predict the lubricant outflow from porous polyimide retainer material

The lubrication performance of oil-impregnated porous polyimide retainer depends on the release of lubricant from the pores. The centrifugal effect induced by rotation is one of the important inducements of lubricant outflow. In this paper, molecular dynamics simulations and experiments are conducted to investigate the lubricant outflow process in the porous polyimide material. The results show that the lubricant outflow can be controlled by five features: pore sizes, rotation speeds, radii of rotation, lubricant viscosities, and surface tensions. Inspired by molecular dynamics simulation results and experimental observations, a characteristic parameter is proposed to evaluate the lubricant outflow state. This new understanding may help expand the use of porous material to improve lubrication in space bearing.