油水乳化液的边界润滑行为及机理分析
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摘要
在滑动轴承的实际应用中,难以避免水对润滑油的侵入污染;因此对油水乳化液的润滑研究至关重要。为探索轴承启停过程中油水乳化液的摩擦学行为及规律,研究了不同水含量对于油水混合体系边界润滑性能及磨损状况的影响。发现在含水量低于99.75%的乳化液中轴承钢间的摩擦因数与纯油润滑时相近,但磨损状况较纯油差;综合摩擦因数与磨损量测试,认为含水量为30%的乳化液,其减摩抗磨效果接近纯油润滑的情况。通过黏度和润湿行为的观测,给出了油水乳化液对于润滑作用机制的原理分析。当乳化液进入润滑接触区时,由于液下超疏水性质,水相极易被挤出接触区,而油相则趋向于在试样表面润湿,从而形成润滑油膜,起到承载和润滑效果。
Oil-water emulsion generally exists in the actual application of the sliding bearings. Hence, the lubricating property of emulsion is of great value for engineering. In order to explore the tribological behaviour of oil-water emulsion during the bearing start-stop process, effects of oil-water emulsions with different water content on boundary lubrication have been investigated. It is found that the friction coefficient of emulsion with water content less than 99.75 wt% is almost similar to that of pure oil, while the wear performance is much worse. Combining the friction and wear results, the emulsion with water content of 30 wt% is considered as the acceptable choice for the engineering applications. By investigating the viscosity and wetting behaviours, the lubrication mechanism of oil-water emulsion has been discussed. Owing to the better wettability than water, the oil phase in emulsion preferentially forms oil film on bearing steel surface, which acts an important role in bearing and lubrication.
Oil-water emulsion generally exists in the actual application of the sliding bearings. Hence, the lubricating property of emulsion is of great value for engineering. In order to explore the tribological behaviour of oil-water emulsion during the bearing start-stop process, effects of oil-water emulsions with different water content on boundary lubrication have been investigated. It is found that the friction coefficient of emulsion with water content less than 99.75 wt% is almost similar to that of pure oil, while the wear performance is much worse. Combining the friction and wear results, the emulsion with water content of 30 wt% is considered as the acceptable choice for the engineering applications. By investigating the viscosity and wetting behaviours, the lubrication mechanism of oil-water emulsion has been discussed. Owing to the better wettability than water, the oil phase in emulsion preferentially forms oil film on bearing steel surface, which acts an important role in bearing and lubrication.
引文
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[2]杨莹,路长厚.水包油乳化液润滑的动静压轴承静特性研究[J].润滑与密封,2008,33(7):25-27.YANG Ying,LU Changhou.Research on the static performance of hybrid bearing lubricated with the emulsion of oil in water[J].Lubrication Engineering,2008,33(7):25-27.
[3]ELIAS H,JEAN B,MICHEL F.Effects of water contamination of lubricants on hydrodynamic lubrication:rheological and thermal modeling[J].Journal of Tribology,2013,135:41707.
[4]王涛,王优强,王建,等.油水两相流润滑轧机油膜轴承的摩擦行为分析[J].表面技术,2016,45(10):89-95.WANG Tao,WANG Youqiang,WANG Jian,et al.Friction behavior of oil film bearing in oil-water two-phase flow lubricated rolling mill[J].Surface Technology,2016,45(10):89-95.
[5]JOSLYN H,CHRISTOPHE P,LEON J,et al.High-speed elastohydrodynamic lubrication by a dilute oil-in-water emulsion[J].Tribology Transactions,2018,61(2):287-294.
[6]BENNER J J,SADEGHI F,HOEPRICH M R,et al.Lubricating properties of water in oil emulsions[J].Journal of Tribology,2006,128:296-311.
[7]MA Liran,LUO Jianbin,ZHANG Chenhui.Effect of solid surface on the formation of thin confined lubricating film of water with micro-content of oil[J].Applied Surface Science,2010,256:6574-6579.
[8]马丽然,雒建斌.高水基乳化液成膜特性及机理研究[J].机械工程学报,2013,49(1):80.MA Liran.LUO Jianbin.Research on the lubricating characteristics and mechanisms of aqueous emulsions[J].Journal of Mechanical Engineering,2013,49(1):80.
[9]LIANG He,GUO Dan,MA Liran,et al.Investigation of film formation mechanism of oil-in-water(O/W)emulsions at high speeds[J].Tribology International,2017,109:428-434.
[10]温诗铸,黄平.摩擦学原理[M].北京:清华大学出版社,2002.WEN Shizhu,HUANG Ping.Principles of tribology[M].Beijing:Tsinghua University Press,2002.
[11]王慰祖,黄平.不同表面粗糙度的摩擦副润滑状态的Stribeck曲线研究[J].摩擦学学报,2004(3):254-257.WANG Weizu,HUANG Ping.Study on the lubrication statr of frictional pairs with different surface roughness based on stribeck curves[J].Tribology,2004(3):254-257.
[12]李鹤尊,张晓昊.利用Stribeck曲线评价润滑油性能的方法研究[J].润滑油,2009,24(5):61-64.LI Hezun,ZHANG Xiaohao.Study on the evaluation method of lubricating oils based on stribeck curves[J].Lubricating Oil,2009,24(5):61-64.
[13]胡志华,刘磊,周芳德,等.油水两相乳化液流动特性的试验研究[J].上海交通大学学报,2005(2):314-316.HU Zhihua,LIU Lei,ZHOU Fangde,et al.An experimental study on the flow characteristics for oil-water emulsions[J].Journal of Shanghai Jiaotong University,2005(2):314-316.