The Effect of Pore Structure on the Self-Lubrication Performance of Porous Liquid Storage Materials

When porous liquid storage self-lubricating materials are subjected to external forces, the lubricating oil stored in the pores will be squeezed out to participate in lubrication due to the deformation of the porous skeleton, thereby improving the lubrication state and achieving self-lubricating function. The self-lubricating performance is closely related to the internal micro pore structure morphology. Therefore, this article adopts 3D printing technology. In order to make the research content suitable for engineering applications, the porosity of 10% to 30% of oil bearing in actual engineering is referenced, A porosity of 20% was selected as the reference value for pore structure design, and three different pore structures of porous liquid storage materials, namely square center circle, square angle circle, and spherical center circle, were prepared. The cell structures of square angle circle and square center circle were square, while the cell structure of spherical center circle was spherical. The effects of different pore structure parameters on the mechanical properties, oil storage performance, permeability performance, and self-lubricating performance of the porous structure were studied under a porosity of 20%. The results showed that under the action of external forces, due to the spherical cell structure of the center circle, its stress and strain distribution was more uniform. As the load increased, lubricating oil could continuously precipitate, while the center circle and corner circle were square cell structures. Under the action of external forces, more obvious stress concentration phenomena would occur, and local large pore deformation hindered the pore channels, leading to hindered precipitation of lubricating oil. Under larger loads, the precipitation of lubricating oil would be hindered; the greater the tortuosity of the pore structure, the greater the flow resistance of the fluid, the smaller the fluidity in the pore channel, and the more difficult it was to precipitate. The smaller the pore size, the stronger the capillary force on the oil, and the lubricating oil could adsorb well in the pores. Therefore, under the effect of thermal effect, due to the air expansion coefficient being greater than the lubricating oil expansion coefficient, the amount of lubricating oil precipitated in this structure was more sensitive to temperature changes and could precipitate more lubricating oil, but the oil storage performance and permeability were poor; under low load conditions, the oil storage and holding performance were positively correlated with the self-lubricating performance of porous materials, and the same conclusion was reached under low-frequency sliding conditions; however, as the load continued to increase, the stress concentration effect of the square corner circle and the square center circle was stronger, and the larger deformation in the local area blocked the hole passage, making it difficult for lubricating oil to flow and weakening the ability of lubricating oil to separate. The spherical center circle could continuously precipitate lubricating oil, improving the lubrication state. At this time, the stress concentration effect of the cell structure gradually became the main factor affecting the self-lubricating performance; with the increase of sliding frequency, the frictional heating power increased, leading to an increase in temperature. The amount of lubricating oil precipitation in all three structures increased, but the square angle circle with smaller curvature could precipitate more lubricating oil under the thermal effect, continuously improving lubrication performance.