Tribological characteristics of phosphonium-based ionic liquids: the role of adsorption layer and tribofilms

IF 6.1 1区工程技术 Q1 ENGINEERING, MECHANICAL

Wear Pub Date : 2025-10-08 DOI:10.1016/j.wear.2025.206382

Shaoli Jiang , Debashis Puhan , Kazuya Kuriyagawa , Théo Yamana , Jean Michel Martin , Liyuan Zhang , Shutian Liu , Koshi Adachi , Motoyuki Murashima

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引用次数: 0

Abstract

Phosphonium-based ionic liquids (ILs) are increasingly recognized as promising lubricant additives, yet their performance under realistic automotive conditions remains poorly understood. This study evaluates three ILs [P₄₄₄₂][DEP], [P₄₄₄₄][C₂C₂PO₂S₂], and [P₆₆₆₁₄][NTf₂], as 1 wt% additives in polyalphaolefin (PAO4), benchmarked against the widely used anti-wear agent zinc dialkyldithiophosphates (ZDDP). Tribological performance was assessed via macroscopic ball-on-disc tests across λ ratios under boundary lubrication at 18 °C, 60 °C, and 80 °C, alongside nanoscale in-lubro AFM experiments to visualize tribofilm formation. SEM/EDX and Raman spectroscopy characterized the wear tracks.

Results show that [P₄₄₄₂][DEP] provides the lowest friction and wear at 18 °C, forming a thin, adsorbed, phosphate-rich tribofilm, whereas all ILs lose anti-wear efficacy at elevated temperatures, sometimes performing worse than neat PAO. AFM analyses reveal that mild sliding is insufficient to trigger tribofilm growth, suggesting that surface wear generates active sites critical for IL effectiveness. High adsorption kinetics of [P₄₄₄₂][DEP] appear fundamental in forming a nanoscale thick, solid-like film, explaining its superior performance.

This work highlights the limitations and potential of phosphonium-based ILs, emphasizing the need for tailored formulations to withstand automotive operating conditions. By linking macroscopic tribology with nanoscale film formation, it provides actionable insights for the design of next-generation additives for automotive and electric vehicle lubricants, bridging a critical gap in the field.

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磷基离子液体的摩擦学特性：吸附层和摩擦膜的作用

磷基离子液体（ILs）作为一种很有前景的润滑油添加剂越来越受到人们的认可，但人们对其在实际汽车工况下的性能仍知之甚少。本研究对三种il [P4442][DEP]， [P4444][C2C2PO2S2]和[P66614][NTf2]作为1 wt%的聚α -烯烃（PAO4）添加剂进行了评价，以广泛使用的抗磨剂二烷基二硫代磷酸锌（ZDDP）为基准。在18°C、60°C和80°C的边界润滑条件下，通过λ比的宏观球盘摩擦性能测试，以及纳米尺度的AFM实验来观察摩擦膜的形成。SEM/EDX和拉曼光谱表征了磨损痕迹。结果表明，[P4442][DEP]在18°C时提供最低的摩擦和磨损，形成一层薄的、吸附的、富含磷酸盐的摩擦膜，而所有il在高温下都失去抗磨效果，有时表现不如纯PAO。AFM分析显示，轻微的滑动不足以触发摩擦膜的生长，这表明表面磨损会产生对IL有效性至关重要的活性位点。[P4442][DEP]的高吸附动力学似乎是形成纳米级厚的固体状薄膜的基础，解释了其优越的性能。这项工作强调了磷基il的局限性和潜力，强调了定制配方以承受汽车操作条件的必要性。通过将宏观摩擦学与纳米级薄膜形成联系起来，该研究为下一代汽车和电动汽车润滑油添加剂的设计提供了可行的见解，填补了该领域的关键空白。

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来源期刊

Wear 工程技术-材料科学：综合

CiteScore

8.80

自引率

8.00%

发文量

280

审稿时长

47 days

期刊介绍： Wear journal is dedicated to the advancement of basic and applied knowledge concerning the nature of wear of materials. Broadly, topics of interest range from development of fundamental understanding of the mechanisms of wear to innovative solutions to practical engineering problems. Authors of experimental studies are expected to comment on the repeatability of the data, and whenever possible, conduct multiple measurements under similar testing conditions. Further, Wear embraces the highest standards of professional ethics, and the detection of matching content, either in written or graphical form, from other publications by the current authors or by others, may result in rejection.