摘要
目的探究离子氮掺杂碳点([NCD_(S)][DEHP])添加剂在非极性基础油中的润滑增效作用。方法通过在基础油PAO4中添加少量质量分数为0.0025%、0.005%、0.01%的[NCD_(S)][DEHP]来配制润滑剂,采用点接触球-盘润滑油膜测量仪对油膜厚度进行测试,在润滑油膜演变过程中,研究了低添加量[NCD_(S)][DEHP]的润滑增益作用。利用原子力显微镜(AFM)和能谱仪(ED_(S))对基体表面形貌和化学组成进行分析,揭示其润滑成膜机制。结果在充分供油条件下,[NCD_(S)][DEHP]对成膜性能影响不大。然而,在限量供油条件下,由于[NCD_(S)][DEHP]中氮掺杂碳点(NCD)阳离子与磷酸酯(DEHP)阴离子的相互作用,能够促进润滑油卷吸进入接触区,使得油膜厚度增加、乏油程度降低,从而提高了基础油的润滑成膜性能。特别地,当添加[NCD_(S)][DEHP]质量分数为0.005%时,润滑成膜性能最佳。结论限量供油条件下,加入少量[NCD_(S)][DEHP]能提高PAO4的润滑性能,改善接触区的乏油程度;机理分析表明,DEHP阴离子在静电作用下会吸附在钢表面;同时,促进NCD阳离子吸附,生成一层吸附膜,提高了润滑成膜能力。
Lubrication is an effective way to alleviate friction and wear,and the development of high-performance lubrication additives is one of the effective ways to improve the lubrication performance of base oils.With the development of nanotechnology,nanomaterials have received wide attention in the field of lubrication due to their unique physicochemical properties.Carbon dots(CD_(S)),as a new type of carbon nanomaterials,have good application prospects in the lubrication field due to their small size,tunable surface functional groups,environmental protection,corrosion inhibition and strong interfacial adsorption ability.Most of the research on CD_(S) focuses on the field of friction and wear,but the research for the field of lubrication has not been carried out yet.In addition,low additive level of[NCD_(S)][DEHP]can improve the friction and wear performance of base oils,but whether it can improve the lubricating film forming properties needs to be further explored.Therefore,the work aims to investigate the lubricating film forming properties of[NCD_(S)][DEHP]at low additive levels.Low additive levels(0.0025%,0.005%,0.01%)of[NCD_(S)][DEHP]were added to PAO4 base oil and then subject to ultrasonic treatment to enable[NCD_(S)][DEHP]to be dispersed uniformly in PAO4.Static settling tests showed that[NCD_(S)][DEHP]could be dispersed in the base oil for at least 30 days.The viscosity of the four lubricants was tested with a rotational rheometer,and the results showed that the addition of[NCD_(S)][DEHP]had minimal effect on the lubricant viscosity.The film thickness was measured with a point contact ball-on-disc lubricant film tester and the surface morphology of the specimens and chemical elements were analyzed by AFM and ED_(S).Under fully flooded conditions,it could be seen by observing the film thickness curves of the four lubricants that[NCD_(S)][DEHP]had minimal effect on the film forming properties.However,under the limited lubricant supply conditions,by comparing the contact zone in the optical interferograms of the oil film with the variation of entrainment velocity and the corresponding film thickness curves of the four lubricants,it was found that low additions of[NCD_(S)][DEHP]could increase the film thickness of lubricants and improve the starvation degree of lubricant in the contact zone,thus improving the lubricating film forming properties of the base oil.In particular,the lubricating film forming properties were optimum when the addition of[NCD_(S)][DEHP]was 0.005%.Based on the optimal mass fraction,the lubricating film forming properties of[NCD_(S)][DEHP]were investigated by changing oil supply level.From the optical interferograms and the degree of oil film collapse in the center of the contact zone,it was found that[NCD_(S)][DEHP]could reduce the width of the oil starvation in the contact zone and improve the effect of oil starvation most obviously at a low oil supply amount(5μL).With the increase of oil supply amount,the lubrication enhancement effect of[NCD_(S)][DEHP]was weakened.[NCD_(S)][DEHP]consists of NCD cations and DEHP anions,which will be adsorbed on the steel surface under the electrostatic effect.At the same time,DEHP anions promote the adsorption of NCD cations and generate a layer of adsorption film,which promotes the lubricant to be entrainment into the contact zone,changes the oil distribution and oil film shape in the contact zone,alleviates the degree of oil starvation,and improves the lubrication film forming ability.
作者
郭杨
刘晓玲
王浩成
孙晓薇
孔薪茹
GUO Yang;LIU Xiaoling;WANG Haocheng;SUN Xiaowei;KONG Xinru(School of Mechanical and Automotive Engineering,Qingdao University of Technology,Shandong Qingdao 266520,China)
出处
《表面技术》
北大核心
2025年第13期51-61,共11页
Surface Technology
基金
国家自然科学基金(51475250,52375190)
泰山学者人才工程(TS20190943)。
关键词
离子氮掺杂碳点
添加剂
成膜性能
阴阳离子
润滑机理
ionic nitrogen-doped carbon dots
additive
film forming properties
anions and cations
lubrication mechanism
作者简介
通信作者:刘晓玲。
