孙楠楠,晁珅,朱桂香,王永强,刘成龙,郭峰.往复运动条件下润湿梯度表面对限量供油润滑的影响[J].表面技术,2023,52(7):130-138.
SUN Nan-nan,CHAO Shen,ZHU Gui-xiang,WANG Yong-qiang,LIU Cheng-long,GUO Feng.Effect of Wettability Gradient on Oil Film Lubrication under Reciprocating Motion with Limited Lubricant Supply[J].Surface Technology,2023,52(7):130-138 |
| 往复运动条件下润湿梯度表面对限量供油润滑的影响 |
| Effect of Wettability Gradient on Oil Film Lubrication under Reciprocating Motion with Limited Lubricant Supply |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.07.010 |
| 中文关键词: 有限量供油 往复运动 油膜厚度 自集油 润湿梯度表面 载荷效应 |
| 英文关键词:limited oil supply reciprocating motion oil film thickness self-collecting oil wettability gradient surface load effect |
| 基金项目:内燃机可靠性国家重点实验室开放课题(skler-202003);国家自然科学基金项目(52175173) |
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| Author | Institution |
| SUN Nan-nan | State Key Laboratory of Engine Reliability, Shandong Weifang 261041, China;Weichai Power Co., Ltd., Shandong Weifang 261041, China |
| CHAO Shen | State Key Laboratory of Engine Reliability, Shandong Weifang 261041, China;Weichai Power Co., Ltd., Shandong Weifang 261041, China |
| ZHU Gui-xiang | State Key Laboratory of Engine Reliability, Shandong Weifang 261041, China;Weichai Power Co., Ltd., Shandong Weifang 261041, China |
| WANG Yong-qiang | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Shandong Qingdao 266520, China |
| LIU Cheng-long | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Shandong Qingdao 266520, China |
| GUO Feng | School of Mechanical and Automotive Engineering, Qingdao University of Technology, Shandong Qingdao 266520, China |
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| 中文摘要: |
| 目的 探究有限量供油条件下，润湿梯度表面对往复运动条件下的油膜润滑增效作用。方法 首先在玻璃试样表面制备一层疏油涂层，降低工作表面润湿性。其次，利用飞秒激光将一定宽度的条状图案刻蚀到掩膜板上，通过掩膜法，利用氧等离子刻蚀技术在玻璃块疏油涂层上构造不同宽度的亲油轨道，形成了润湿梯度表面。然后使用往复运动光弹流膜厚测量仪对亲油轨道的膜厚及油池变化进行测试。试验选用低黏度的PAO4基础润滑油，限量供给0.04 μL。钢球与玻璃试样表面构成点接触往复运动摩擦副模型。结果 具有一定亲油轨道宽度(0.2、0.4 mm)的润湿性梯度表面具有较好的集油性能。润湿性梯度表面在往复运动行程中心位置作用最为明显，在所给试验条件下膜厚最大为原始表面的3倍。钢球-钢块接触副的摩擦测试结果表明，本文提出的润湿梯度表面使摩擦因数最高下降30%。另外，由于载荷效应导致接触区外侧毛细集油作用减弱，乏油程度增加，随着载荷增加，润滑油膜减小。油滴在一定宽度亲油轨道的扩散仿真结果说明润湿性梯度表面可以有效地将润滑油限制在轨道内，有利于往复运动过程中润滑剂的回流。结论 提出的润湿性梯度表面有较强的集油作用，改善往复运动弹流接触副的供油和润滑状态。 |
| 英文摘要: |
| Starvation can usually be found in lubrication of machine elements due to insufficient oil replenishment, and the present study is to explore the role of wettability gradient on the lubrication film building under reciprocating motion with limited oil supply. On the glass block specimens, oleophilic lubrication tracks with oleophobic side regions were prepared. Oleophobic AF (anti-fingerprint) layers were fabricated on the glass block surface. With masks by femtosecond laser, oxygen plasma etching was used to remove prescribed strip area of the oleophobic AF layer on the glass block surface in such a way that oleophilic track with different width were obtained. A custom-made optical EHL (elastohydrodynamic lubrication) test rig, which was capable of reciprocating motion with pure rolling, was used to measure the film thickness and oil pools in the present study. Lubricated point contact was formed between the steel ball and the prepared glass block surface. PAO4 base oil was employed in the test with a limited supply of 0.04 μL. AFM measurement showed that there was typical nanoscale papillae structure on the AF layer, which contributed as well to the oleophobic behaviours of the low surface energy surface of the glass block. The wettability gradient was justified by the movement of a PAO4 droplet to the glass region when it was placed on the boundary of the AF region and the glass region due to the high surface energy of the original glass block. Measurements of film thickness and oil pools showed that the wettability gradient, which was created at the two sides of the oleophilic tracks, generally demonstrated better oil replenishment performance when the track width was 0.2 mm and 0.4 mm, and then the film thickness was higher. On the contrary, the film thickness with a full AF layer (the oleophilic track width was 0 mm) was even lower than that with the original glass block due to its weak affinity to the lubricant. Moreover, it was observed that the film thickness was mostly increased at the center of the stroke, and the film thickness may be up to 3 times as much as that by the original surface. At the two stroke ends only slight film thickness increase was obtained. For film thickness enhancement, wettability gradient worked more efficiently under high frequency or at high speed. When the oleophilic track width was 0.8 mm, which was much larger than the diameter of the contact area, the film thickness was similar to that of the original glass surface, indicating that the induced oil replenishment did not work. It can be understood that when the oleophilic track width and the contact region were of the similar size, the lubricating performance can be improved. A steel ball-on-steel block test was also used to assess the role of wettability gradient, and it was observed that the friction with wettability gradient lubrication track was always lower than that without wettability gradient, and the friction difference between the two increased with running time, and a friction decrease of 30% could be realized. In addition, it was displayed that at low speed, the load had no obvious influences on the film thickness with limited lubricant supply. At high speed, more starvation was observed for heavy loads, thus the wettability gradient worked better for such conditions. At last, the enhanced oil transportation by wettability gradient was numerically investigated with computational fluid dynamics. The simulation results show that the wettability gradient surface can effectively confine the lubricating oil in the track, which is beneficial to the oil replenishment during the reciprocating motion. The proposed wettability gradient is proved to be an effective way to enhance oil replenishment on the lubricated surface, and consequently the oil supply and lubrication state with reciprocating motion can be significantly improved. |
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