电场驱动下卵磷脂颗粒在织构表面的聚集与润滑

It is an advanced lubrication technology to manipulate the aggregation of lecithin particles by an electric field, which can improve the lubrication properties of friction surfaces by the synergistic effect of lubricating particles and texture. This work aims to solve the problems of high adhesion wear and friction of titanium alloy (Ti6Al4V) and ultra-high molecular weight polyethylene (UHMWPE) artificial joint materials. The lubrication lecithin particles were aggregated at the friction interface by an electric field to achieve the effect of friction reduction and anti-wear. The lubrication is related to the particle concentration, and only when the critical concentration is reached, will a better lubrication be shown. If the active boundary lubricant particles aggregate and migrate in a direction, the lubrication of the previously lacking lubrication interface can be improved. The oil-in-water nanoemulsion was successfully prepared with deionized water and lecithin as the continuous phase and dispersed phase. The average particle size of lecithin without any dispersant was 2 087 nm; After adding oleic acid dispersant, the average particle size was 305.2 nm, indicating that the particle size was reduced and the dispersion performance was improved. When sodium dodecyl benzene sulfonate (SDBS) was used as a dispersant in the nanosolution by ultrasonic wave, the resulted particle size ranged from 200 to 500 nm. An electrophoresis bench of lecithin particles was built, and electrophoresis experiments were carried out on different concentrations of emulsion with graphite as the cathode and a textured titanium alloy disc as the anode, and the electrophoresis parameters such as voltage were changed, and the texture was filled with emulsion particles. The tests were set at 5 V, 10 V, 15 V, and 20 V, and the solution concentration was 0.1%, 0.2%, and 0.3%. The dimple depth of textured surface of the energized disc was less than that of the disc with the same surface texturing parameter unenergized in lecithin solution by 9.9 μm, which confirmed that lecithin nanoparticles aggregated in the dimple of the textured surface after energizing. At a large current density, the entire surface of the textured surface was covered by a lecithin layer and slightly oxidized; The main component of the surface oxides was rutile TiO₂, which would accelerate the wear of the UHMWPE. At a small current density, it could be observed that the lecithin particles were filled in dimples of the surface texture, which had good lubricating properties and achieved a coefficient of friction as low as 0.075. At a lecithin solution concentration of 0.3%, the texture exhibited the best low-friction properties, and UHMWPE had the lowest wear rate. Since the lecithin particles in the texture of the friction interface were continuously transported to the friction gap with the shear fluid, the phospholipid layers formed a film on the surface after demulsification, which had better lubrication. In the study, lecithin nanoparticles were filled in the surface texture of Ti6Al4V alloy by electrophoresis, which improved the wear resistance of the material, and the preparation and electrophoresis-related processes of lecithin were explored, and the anti-wear mechanism was analyzed. It is expected to improve the life of artificial joints with Ti6Al4V alloy and UHMWPE.