Superlubricity of polyethylene glycol solutions: Running-in effects, thickness changes, and rheology

IF 8.2 1区工程技术 Q1 ENGINEERING, MECHANICAL

Friction Pub Date : 2025-08-04 DOI:10.26599/frict.2025.9441161

Tomáš Poláček, Martin Kadlec, Jiří Smilek, Martin Hartl, Petr Šperka

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Abstract

The role of additives in liquid superlubricity is regarded as a crucial element of the running-in process due to their role in reducing friction. Nevertheless, there has been minor investigation into rheological changes that occur during the process. This paper presents an examination of the evolution of film thickness over time and its subsequent behavior. The primary experiments were performed on an optical ball-on-disk tribometer, with the ability to control the percentage of slip. The film thickness was evaluated by optical interferometry and its rheological behavior was subsequently researched by rotational rheometer and viscometer. It was discovered that the primary contribution to the reduction in friction during running-in is better contact separation caused by the evaporation of water. However, the global behavior of the solution was found to have been changed by formation of a convoluted compound and probably by adsorption to contact surfaces. It causes a behavior that is more complex than that predicted by common elastohydrodynamic equations, but may result in a reduction of friction due to an increased separating layer.

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聚乙二醇溶液的超润滑性：磨合效应、厚度变化和流变性

添加剂在液体超润滑中的作用被认为是磨合过程中的关键因素，因为它们具有减少摩擦的作用。然而，对这一过程中发生的流变变化进行了少量调查。本文介绍了薄膜厚度随时间的演变及其后续行为的研究。初步实验是在一个光学球盘摩擦计上进行的，该摩擦计具有控制滑动百分比的能力。用光学干涉法测定了膜的厚度，并用旋转流变仪和粘度计研究了膜的流变特性。研究发现，磨合过程中减少摩擦的主要原因是水的蒸发使接触分离效果更好。然而，发现溶液的整体行为已经被一个卷曲的化合物的形成改变，可能是由于吸附到接触面。它导致的行为比普通弹性流体动力学方程预测的更为复杂，但由于分离层的增加，可能导致摩擦的减少。

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来源期刊

Friction Engineering-Mechanical Engineering

CiteScore

12.90

自引率

13.20%

发文量

324

审稿时长

13 weeks

期刊介绍： Friction is a peer-reviewed international journal for the publication of theoretical and experimental research works related to the friction, lubrication and wear. Original, high quality research papers and review articles on all aspects of tribology are welcome, including, but are not limited to, a variety of topics, such as: Friction: Origin of friction, Friction theories, New phenomena of friction, Nano-friction, Ultra-low friction, Molecular friction, Ultra-high friction, Friction at high speed, Friction at high temperature or low temperature, Friction at solid/liquid interfaces, Bio-friction, Adhesion, etc. Lubrication: Superlubricity, Green lubricants, Nano-lubrication, Boundary lubrication, Thin film lubrication, Elastohydrodynamic lubrication, Mixed lubrication, New lubricants, New additives, Gas lubrication, Solid lubrication, etc. Wear: Wear materials, Wear mechanism, Wear models, Wear in severe conditions, Wear measurement, Wear monitoring, etc. Surface Engineering: Surface texturing, Molecular films, Surface coatings, Surface modification, Bionic surfaces, etc. Basic Sciences: Tribology system, Principles of tribology, Thermodynamics of tribo-systems, Micro-fluidics, Thermal stability of tribo-systems, etc. Friction is an open access journal. It is published quarterly by Tsinghua University Press and Springer, and sponsored by the State Key Laboratory of Tribology (TsinghuaUniversity) and the Tribology Institute of Chinese Mechanical Engineering Society.