Study On The Influence Of Liquid Droplet Lubricant Supply On Slider-on-disc Contact Film Thickness Under Limited Lubricant Supply Based On Surface Modification

Conformal contact is a typical contact in mechanical parts.Generally,to guarantee the lubrication performance,excessive amount of lubricant is supplied and thus results in the high power consumption and waste of resources.Therefore,tribologists propose the concept of lubrication with limited lubricant supply,that is,through controlling lubricant supply the machine parts can work in the optimal lubricant regime for reducing friction and wear.In this thesis,surface modification is used to realize more usage of oil to improve the lubrication performance of conformal contact under limited lubricant supply.With the slider bearing lubricant film test rig,droplet oil supply is obtained by the way of transfer film and surface coating with surface texture,and the film thickness was experimentally studied under limited oil supply.According to the experimental results,the influences of different oil supply models on the oil film lubrication of the slider-on-disc contact are analyzed numerically.Firstly,the influences of oleophobic FAS(C₁₃H₁₃F₁₇O₃Si)film on lubricating film are studied under limited lubricant supply.Part of the FAS film can be spontaneously transferred to the glass disc surface through the oil film.Due to dewetting of FAS transfer film,the oil replenishment at the outlet of the contact area is significantly enhanced.Lubricant distribution on the disc surface changes from side-ridge-type to liquid-drop-type and aggregates to the central lubrication track,which can enhance the oil supply at the inlet,and therefore higher film thickness is obtained.Secondly,using the glass disc with anti-finger AF film,the influence of the surface texture of the inlet siden of the slider on the lubricant film was studied under limited oil supply.The lubricant on the surface with coated AF presented itself in the form of droplet under the limited oil supply.As speed increases,the lubricant droplet can creep to the front side of the slider owing to the capillary force.The lubricant was collected at the front of the inlet area and the contact area could not obtain an effective oil film-bearing capacity.Increasing lubricant supply and using low viscosity lubricant can alleviate the creep phenomenon.The surface texture on the slider side can actively transport the lubricant to the contact area,and significantly enhance the lubrication performance.Finally,in terms of the distribution of the lubricant on the track observed in the experiments,two different oil supply models including the liquid droplet model and the side-ridge model were numerically analyzed.The influences of the speed,lubricant supply,load,and lubricant viscosity on the film pressure and the film thickness are studied,and the lubrication performance characteristics were compared between the droplet model and the two-side-ridge model.The results of the numerical analysis are in good agreement with the experiments.