Thin film lubrication in the past 20 years

Ma, Liran

doi:10.1007/s40544-016-0135-5

Cited by 72 publications

(31 citation statements)

References 123 publications

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“…Thin film lubrication was proposed by Luo's group 20 years ago in which the main lubricating effect is from the ordered molecules, and so the shear stress should be higher than that of the fluid molecules [76,77]. Therefore, finding ways to realize superlubricity in thin film lubrication become a great challenge for tribologists.…”

Section: Superlubricity In Thin Film Lubrication Regionmentioning

confidence: 99%

A review of recent advances in tribology

et al. 2020

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The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade. This review takes stock of the recent advances in research pertaining to different aspects of tribology within the last 2 to 3 years. Different aspects of tribology that have been reviewed including lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology. This review attempts to highlight recent research and also presents future outlook pertaining to these aspects. It may however be noted that there are limitations of this review. One of the most important of these is that tribology being a highly multidisciplinary field, the research results are widely spread across various disciplines and there can be omissions because of this. Secondly, the topics dealt with in the field of tribology include only some of the salient topics (such as lubrication, wear, surface engineering, biotribology, high temperature tribology, and computational tribology) but there are many more aspects of tribology that have not been covered in this review. Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.

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Section: Superlubricity In Thin Film Lubrication Regionmentioning

confidence: 99%

A review of recent advances in tribology

et al. 2020

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“…Even though it is difficult to directly observe the formed ordered layers [9], PAGs [39] and PAOs [8,11,41] have been widely used to study TFL owing to their ability to form ordered layers on steel surfaces. Taking PAGs as an example, because they have an ether bond, it makes the molecules highly polar, and thus, they can easily be adsorbed on steel surfaces and form ordered layers.…”

Section: Resultsmentioning

confidence: 99%

“…Clearly, a transition regime is expected between EHL and BL, where the fluid layer, ordered layers, and adsorbed layers (or tribochemical layers) coexist and function to reduce the friction. Decades later, a new lubrication regime with this three-layer structure was proposed and named as thin-film lubrication (TFL, 1996) [7,8]. The molecular model of TFL has been directly proven by experimental detection [9].…”

Section: Introductionmentioning

confidence: 99%

“…By controlling the alignment of nematic liquid crystal molecules in a nanogap, a nano-sandwich structure consisting of an adsorbed layer, an ordered-molecule layer, and a fluid layer was demonstrated, which was a typical TFL model [9]. The TFL theory depicts the entire map of the lubrication regimes as well as provides insight into the molecular form in the confined liquid layers [8]. In the TFL regime, the thickness of the ordered layers is related to the initial viscosity and molecular size of the lubricant, polarity of the lubricant molecules, and characteristics of the solid surfaces [7].…”

Section: Introductionmentioning

confidence: 99%

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Molecular behaviors in thin film lubrication—Part three: Superlubricity attained by polar and nonpolar molecules

Halmans

2018

Friction

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In thin-film lubrication (TFL), generally, the viscosity of the lubricant and its coefficient of friction (CoF) increase. Finding a method to reduce the CoF in TFL is a significant challenge for tribologists. In the present work, we report a robust superlubricity attained by using polyalkylene glycols (PAGs, polar molecules) and poly-α-olefins (PAOs, nonpolar molecules) as lubricants on steel/steel friction pairs that have been pre-treated by wearing-in with polyethylene glycol aqueous solution (PEG(aq)). A steady superlubricity state with a CoF of 0.0045 for PAG100 and 0.006 for PAO6 could be maintained for at least 1 h. Various affecting factors, including the sliding velocity, normal load, and viscosity of the lubricants, were investigated. Element analysis proved that composite tribochemical layers were deposited on the worn region after the treatment with PEG(aq). These layers were formed by the tribochemical reactions between PEG and steel and composed of various substances including oxides, iron oxides, FeOOH, and Fe(OH) 3 , which contributed to the superlubricity. In addition to the tribochemical layers, ordered layers and a fluid layer were formed by the PAGs and PAOs during the superlubricity periods. All the three types of layers contributed to the superlubricity, indicating that it was attained in the TFL regime. Accordingly, a mechanism was proposed for the superlubricity of the PAGs and PAOs in the TFL regime in this work. This study will increase the scientific understanding of the superlubricity in the TFL regime and reveal, in the future, the potential for designing superlubricity systems on steel surfaces for industrial applications.

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“…These results help to fill the blank in the theory of lubrication under charged conditions, as well as provide guidance for the design of lubrication systems in practice. It has been confirmed by a large number of experiments that the lubrication/friction properties can be tuned by an external electric field [122][123][124]. However, unlike specific electrical damages that have common appearances, the electrical responses of the lubrication properties are significantly different, and multiple mechanisms are involved.…”

Section: Fundamental Researches On Tribological Performance In An Elementioning

confidence: 97%

Electrical bearing failures in electric vehicles

2020

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In modern electric equipment, especially electric vehicles, inverter control systems can lead to complex shaft voltages and bearing currents. Within an electric motor, many parts have electrical failure problems, and among which bearings are the most sensitive and vulnerable components. In recent years, electrical failures in bearing have been frequently reported in electric vehicles, and the electrical failure of bearings has become a key issue that restricts the lifetime of all-electric motor-based power systems in a broader sense. The purpose of this review is to provide a comprehensive overview of the bearing premature failure in the mechanical systems exposed in an electrical environment represented by electric vehicles. The electrical environments in which bearing works including the different components and the origins of the shaft voltages and bearing currents, as well as the typical modes of electrical bearing failure including various topographical damages and lubrication failures, have been discussed. The fundamental influence mechanisms of voltage/current on the friction/ lubrication properties have been summarized and analyzed, and corresponding countermeasures have been proposed. Finally, a brief introduction to the key technical flaws in the current researches will be made and the future outlook of frontier directions will be discussed.

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Thin film lubrication in the past 20 years

Cited by 72 publications

References 123 publications

A review of recent advances in tribology

A review of recent advances in tribology

Molecular behaviors in thin film lubrication—Part three: Superlubricity attained by polar and nonpolar molecules

Electrical bearing failures in electric vehicles

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