| GUAN Qiang,ZHANG Xu-wei,HE Jiao,LI Zheng,WEI Yun-ling,REN Fu-e,GONG Nan,DING Hao-hao,WANG Wen-jian.Effect of WS2 and h-BN Nano-additive on Extreme Pressure and Anti-wear Properties of Semi-fluid Lithium Base Grease[J],51(8):233-242 |
| Effect of WS2 and h-BN Nano-additive on Extreme Pressure and Anti-wear Properties of Semi-fluid Lithium Base Grease |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.08.019 |
| KeyWord:WS2 h-BN nano additive anti-wear extreme pressure reactive film |
| Author | Institution |
| GUAN Qiang |
School of Mechanical Engineering, Southwest Jiaotong University, Chengdu , China |
| ZHANG Xu-wei |
Chengdu Shuguang Petrochemical Petrochemicals Co., Ltd., Chengdu , China |
| HE Jiao |
Chengdu Shuguang Petrochemical Petrochemicals Co., Ltd., Chengdu , China |
| LI Zheng |
Department of Mechanical and Electrical Engineering, Qingdao University of Technology, Shandong Linyi , China |
| WEI Yun-ling |
Department of Mechanical and Electrical Engineering, Qingdao University of Technology, Shandong Linyi , China |
| REN Fu-e |
Department of Mechanical and Electrical Engineering, Qingdao University of Technology, Shandong Linyi , China |
| GONG Nan |
Chengdu Shuguang Petrochemical Petrochemicals Co., Ltd., Chengdu , China |
| DING Hao-hao |
School of Mechanical Engineering, Southwest Jiaotong University, Chengdu , China |
| WANG Wen-jian |
School of Mechanical Engineering, Southwest Jiaotong University, Chengdu , China |
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| Abstract: |
| As a new type of lubrication additive, nanomaterial can significantly improve the lubrication characteristics of the lubricant, which can effectively reduce the friction and wear between two moving surfaces and maintain a good lubrication effect to protect and repair the damaged surface under some special working conditions. In this article, the effects of two kinds of lamellar nano-additives disulfide (WS2) and hexagonal boron nitride (h-BN) on the extreme pressure and anti-wear properties of lithium-based grease were studied, and the differences in lubrication properties between the two kinds of nanomaterials were compared. With WS2 and h-BN nanomaterial as additives, 100SN and KH150BS oil were uniformly mixed in a ratio of 3:1 as base oil, and 2# lithium grease as soap source, 00# lithium grease containing WS2 and h-BN nano-additives was prepared by the high-speed agitator and three-roll grinder respectively. At first, the dropping point and cone penetration of grease were measured, and then the long-wear and extreme pressure tests were carried out by using the MRS10A four-ball wear tester. In order to discuss the mechanism of action of WS2 and h-BN nano-additives, the scanning electron microscope (SEM) and optical microscope (OM) were used to observe the morphological characteristics of wear spots, and the elements on the wear spot surface were detected and analyzed by X-ray photon-electron spectroscopy (XPS). The results show that compared with base grease, the friction coefficient and wear spot diameter of grease containing WS2 nano additive can be reduced by 12.7% and 10.5% at the concentration of 0.5wt.%. The grease containing h-BN nano-additive can reduce the friction coefficient by 4.2% at the concentration of 0.25wt.%, and the wear spot diameter can be reduced by 22.14% at the concentration of 0.5wt.%; The addition of two kinds of nano-additives increased the maximum non-seizure load of grease by 40%. The morphology and contour characteristics observed by SEM and OM can show that WS2 and h-BN nano additives can effectively improve the surface quality of the wear spot, reduce the surface roughness of the wear spot, and play a certain role in repairing the worn surface. XPS element analysis shows that the WS2 nano additive will undergo tribo-chemical reaction on the friction surface to form Fe2O3, FeO, and FeS2 reaction films, while on the h-BN wear surface, it will mainly react to form B2O3, Fe2O3, FeO, and other reaction films. The formation of friction reaction film can improve the extreme pressure and anti-wear performance of lubricating grease, and the relatively low shear force in the case of interlamellar slip is the main reason why nano-additives can reduce the friction coefficient. The railway locomotive traction gear grease compounded with WS2 and h-BN nano additives is tested for physical and chemical performance according to the technical indicators of Q/CR762—2020 "Railway Locomotive Traction Gear Grease", and the measurement results fully meet Q/CR762—2020 "Railway Locomotive Traction Gear" Grease" standard. The film formation and slip effect of WS2 and h-BN nano-additives on the wear spot surface are the main reason for improving the lubrication performance of the grease. WS2 can better reduce the friction coefficient compared with h-BN, while h-BN can better reduce the wear, and both can effectively improve the extreme pressure performance of the grease. |
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