| PAN Ling,WU Yunli,LIAN Jinliang,ZHENG Kaikui,GUO Jinyang.Influence of Thickener Components on Friction Performance of Lubricating Grease[J],54(5):83-92 |
| Influence of Thickener Components on Friction Performance of Lubricating Grease |
| Received:April 13, 2024 Revised:July 30, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.05.006 |
| KeyWord:friction reaction film thickening agent components friction performance lubricating grease molecular dynamics |
| Author | Institution |
| PAN Ling |
School of Advanced Manufacturing, Fuzhou University, Fujian Jinjiang , China;School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou , China |
| WU Yunli |
School of Advanced Manufacturing, Fuzhou University, Fujian Jinjiang , China |
| LIAN Jinliang |
School of Advanced Manufacturing, Fuzhou University, Fujian Jinjiang , China |
| ZHENG Kaikui |
School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou , China |
| GUO Jinyang |
School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou , China |
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| Abstract: |
| The influence of dicarboxylic acid and boric acid in the thickening agent components on the lubrication performance of lubricating grease on the surface of friction pairs was studied. The rough surface boundary lubrication system models with sinusoidal convex peaks and smooth wall reaction force field boundary lubrication system models were established respectively. The molecular dynamics simulation method was used to study the load-bearing capacity, shear resistance, and friction performance of the 12-hydroxystearic acid & azelaic acid grease system (A lubricating grease), the 12-hydroxystearic acid & dodecanedioic acid grease system (B lubricating grease), and the 12-hydroxystearic & acid azelaic & acid boric acid grease system (C lubricating grease). At the same time, lubricating grease with the same composition and content as the simulated one was prepared according to common grease preparation methods. Bond formation and frictional chemical reaction film analysis were conducted on C lubricating grease. Finally, combined with micro friction and wear tests of lubricating grease, the effects of dicarboxylic acid chain length and boric acid on the friction performance of lubricating grease were revealed. The results indicated that as the pressure increased, the density of lubricating grease increased and the phenomenon of delamination became more and more obvious during the pressurization stage. C lubricating grease containing boric acid in the component had a lower density in all areas, exhibiting the best load-bearing capacity when the pressure Pz=50 MPa. During the shearing process, C lubricating grease always separated the two rough peaks, the oil film did not break, and the bearing capacity was the highest. The maximum stress values of the B lubrication system containing long-chain dicarboxylic acid and the C lubrication system containing boric acid were reduced by 27.1% and 57.1%, respectively, compared with lubricating grease A. In the meanwhile, the friction coefficient of C lubricating grease was relatively stable at 0.090, which was 16.7% and 22.2% lower than that of B lubricating grease and A lubricating grease, respectively, indicating that C lubricating grease had excellent mechanical properties. Finally, the friction coefficient value of C lubricating grease was relatively stable, fluctuating within the range of 0.075-0.095. The friction and wear results indicated that the addition of boric acid to the thickening agent component significantly improved the physicochemical properties of lubricating grease, with friction coefficients and mean values ranging from 0.085 to 0.095 and 0.091, respectively. The simulation results were consistent with the experimental results. Through the above research, it can be found that compared with lubricating grease containing short chain dicarboxylic acid in thickeners, lubricating grease containing long chain dicarboxylic acid exhibits better shear resistance and friction performance. The structure of the thickener is strengthened, and lubricating grease exhibits better wear resistance and friction reduction performance when boric acid is added to the thickener. This is because under the action of boric acid, the lithium soap and boric acid groups in lubricating grease not only form coordination bonds, but also form a frictional chemical reaction film on the solid wall surface, significantly improving the physical and chemical properties of lubricating grease. |
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