Competitive Adsorption of Ionic Liquids Versus Friction Modifier and Anti-Wear Additive at Solid/Lubricant Interface—Speciation with Vibrational Sum Frequency Generation Spectroscopy

Lubricants

卷:8

Dien Ngo¹  SeongH. Kim¹  Huimin Luo²  Jun Qu³  Xin He³ 

[1] Department of Chemical Engineering and Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA;

[2] Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA;

[3] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA;

关键词: ionic liquids;    lubricants;    sum frequency generation spectroscopy;    base oil;    additives;   

DOI  :  10.3390/lubricants8110098

来源: DOAJ

【 摘 要 】

A modern lubricant contains various additives with different functionalities and the interactions or reactions between these additives could induce synergistic or antagonistic effects in tribological performance. In this study, sum frequency generation (SFG) spectroscopy was used to investigate competitive adsorption of lubricant additives at a solid/base oil interface. A silica substrate was used as a model solid surface. The lubricant additives studied here included two oil-soluble ionic liquids (ILs, [N888H][DEHP] and [P8888][DEHP]), an antiwear additive (secondary ZDDP), an organic friction modifier (OFM), and a dispersant (PIBSI). Our results showed that for mixtures of ZDDP and IL in a base oil (PAO4), the silica surface is dominated by the IL molecules. In the cases of base oils containing OFM and IL, the silica/lubricant interface is dominated by OFM over [N888H][DEHP], while it is preferentially occupied by [P8888][DEHP] over OFM. The presence of PIBSI in the mixture of PAO4 and IL leads to the formation of a mixed surface layer at the silica surface with PIBSI as a major component. The SFG results in this investigation provide fundamental insights that are helpful to design the formulation of new lubricant additives of desired properties.

【 授权许可】

Unknown