Effect of external electric field on liquid film confined within nanogap

The lubricating properties of organic phosphate ester (DPZ) aqueous solution were investigated using the tribological testers and the home-built thin film interferometry. Experimental results indicate that DPZ can adsorb on the surfaces of rubbing pair, reduce the friction coefficient of boundary lubrication, and significantly improve the anti-seizure properties of water. Under the elastohydrodynamic lubrication (EHL), the lubricating film thickness decreases with the DPZ concentration increasing. It is thought that a preferential slip plane, which is created against the adjacent layer between the hydration sheath around the polar headgroups of DPZ molecules and bulk water, dramatically weakens the water film by breaking the H-bond network around surface.

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“…3, which was described in references [13,14]. A contact is formed between the flat surface of a rotating glass disc and a reflective steel ball.…”

Section: Film Thickness Measurementsmentioning

confidence: 99%

“…Organic phosphate ester (DPZ): a FTIR spectrometer and b chemical formula (R-alkyl chain: C7-C20; n:[5][6][7][8][9][10][11][12][13][14][15] …”

mentioning

confidence: 99%

Lubricating Properties of Organic Phosphate Ester Aqueous Solutions

Liu

Guo

et al. 2009

Tribol Lett

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“…Under charged condition, abundant microbubbles appeared around the lubricated contact area (Fig. 11), which was proposed to be attributed to local overheating [83,107]. Correspondingly, when moving to the outer region, the bubble tended to be unstable and the coalescence sometimes occurred (Fig.…”

Section: Microbubble Effectsmentioning

confidence: 98%

“…11). The generation and collapse of microbubbles can destabilize the lubrication, which can lead to additional noise and vibration in a bearing [107]. In addition, lubricants containing microbubbles are more susceptible to electrical breakdown.…”

Section: Microbubble Effectsmentioning

confidence: 99%

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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“…When these microbubbles move outward from the contact, they have a tendency to coalesce. Not only the lubricant having microbubbles is susceptible to electrical breakdown but also to destabilization (Xie et al, 2008b). AC frequency and electrode insulation also affect the microbubble formation.…”

Section: Mechanisms Of Electric Breakdown Of Lubricantsmentioning

confidence: 99%

Performance Characteristics of Lubricants in Electric and Hybrid Vehicles: A Review of Current and Future Needs

et al. 2020

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Electric and hybrid vehicles are gaining increasing attention in recent years. The distinguished difference between electric/hybrid vehicles from conventional ones is the intermittent on-and-off control of the internal combustion engine, whereas the electric vehicles operate on electrical motors. This difference creates new requirements in lubricants with performance characteristics that are otherwise uncritical: electrical properties (such as electrical conductivity and breakdown voltage) and thermal properties (thermal conductivity, specific heat, among others), in addition to fluidic performance that we have studied for decades. In this review, we discuss about lubricants for electric and hybrid vehicles in the following aspects. Starting with a brief historic review, we gathered information about current needs and challenges in electric and hybrid vehicles. We then compared the properties of lubricants, followed by the performance difference of those vehicles in terms of frictional performance, thermal management, and dielectric breakdown. Performance parameters are critically dependent on the properties of lubricants that are crucial for energy efficiency and reliability. This review can be used as a guidance for the future design of advanced lubricants for electric and hybrid vehicles.

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Effect of external electric field on liquid film confined within nanogap

Cited by 27 publications

References 20 publications

Lubricating Properties of Organic Phosphate Ester Aqueous Solutions

Lubricating Properties of Organic Phosphate Ester Aqueous Solutions

Electrical bearing failures in electric vehicles

Performance Characteristics of Lubricants in Electric and Hybrid Vehicles: A Review of Current and Future Needs

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