Electric Contacts

Holm, Ragnar

doi:10.1007/978-3-662-06688-1

Cited by 1,526 publications

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“…Some examples of these models are Suh delamination theory of wear (23), Rabinowicz model for abrasive wear (24) and the Archard's wear equation (25,26). Wear occurs by different interfacial mechanisms and all these mechanisms can contribute in changes in the topography.…”

Section: Wear Predictionmentioning

confidence: 99%

An experimental and analytical study of the effect of water and its tribochemistry on the tribocorrosive wear of boundary lubricated systems with ZDDP-containing oil

Parsaeian

Ghanbarzadeh

Wilson

et al. 2016

Wear

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 An experimental and analytical study of the effect of water and its tribochemistry on the tribocorrosive wear of boundary lubricated systems with ZDDP-containing oil AbstractWater has long been recognised as a contaminant in lubricants. It can affect wear performance, especially in bearing systems, in complex ways. Water can also induce corrosion, which in turn can enhance wear. The individual parts of any tribocorrosion system are related to a complex mix of system parameters such as lubricant and additives, relative humidity and temperature. The effect of different water concentrations and different temperatures has been studied experimentally in this work. A modification to Archard's wear coefficient was applied with respect to the experimental measurements. The new wear model considering the effect of water was implemented into the previously-reported numerical model to develop a new semi-deterministic numerical wear model adapted to the tribocorrosion system in this work. IntroductionWater in lubricants has been known to be a contaminant for many systems (1-3). It is shown to affect the wear performance, especially in bearing systems, in different ways (4-10). The presence of water in lubricated tribosystems, particularly in bearing applications, can cause corrosion and hydrogen embrittlement, which can increase wear and friction (8). In addition, even small amount of water in parts per million (ppm) may accelerate the oxidation of oil (11).To investigate the effect of water contamination on the performance of lubricated systems, it is essential to know the form that water exists in the oil (12). Water can be present in oil in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 two different forms which are dissolved water and free water (13). D...

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Section: Wear Predictionmentioning

confidence: 99%

An experimental and analytical study of the effect of water and its tribochemistry on the tribocorrosive wear of boundary lubricated systems with ZDDP-containing oil

Parsaeian

Ghanbarzadeh

Wilson

et al. 2016

Wear

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“…In macroscopic electrical contacts this result is known as the "ϕ − Θ relation". 7 Here, we will re-derive it from a microscopic theory and determine the quantity γ e−e in terms of the properties of the junction and of the electron liquid. This theory needs to take into account the influence of electron-electron interactions on both the heat production and dissipation.…”

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confidence: 99%

Local Electron Heating in Nanoscale Conductors

2006

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The electron current density in nanoscale junctions is typically several orders of magnitude larger than the corresponding one in bulk electrodes. Consequently, the electron-electron scattering rate increases substantially in the junction. This leads to local electron heating of the underlying Fermi sea in analogy to the local ionic heating that is due to the increased electron-phonon scattering rates. We predict the bias dependence of local electron heating in quasi-ballistic nanoscale conductors, its effect on ionic heating, and discuss possible experimental tests of our results.In the process of electrical charge transport, the dissipation of energy via heat production plays a significant role. This effect is of particular importance in nanoscale systems, like e.g., atomic or molecular structures between bulk electrodes, 1 since it determines their structural stability under current flow. It is now understood that the large current densities in nanojunctions, compared to their bulk counterparts, may lead to substantial heating of the nanostructure ions.2,3,4 This effect is directly related to the consequent increase of the electronphonon scattering rates in the junction. In quasi-ballistic systems, i.e. when the mean free path is much longer than the dimensions of the nanostructure, by assuming a bulk lattice heat conduction mechanism, the local ionic temperature is predicted to be T ion ∝ √ V , where V is the applied bias. 2,3,4 For the same reasons, and due to the viscous nature of the electron liquid, 5 we here suggest that the local increase of the electron-electron scattering rate in the junction gives rise to local heating of the underlying Fermi sea, whether the system has one or many conducting channels. This local electronic temperature would also affect the electron-phonon scattering rates, and consequently the bias dependence of the ionic temperature.In this Letter, we first estimate the bias dependence of the local electron temperature in quasi-ballistic systems, assuming no ionic heating is produced. We will then determine the effect of the electron heating on the bias dependence of the ionic temperature. We finally discuss possible experiments to test our predictions. *

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“…The injection of electrons from a metal electrode at the interface of the surrounding gas is a phenomenon of primary importance concerning the initiation and evolution of dielectric breakdown [1]. This phenomenon is practically met during the opening stage of all kinds of power switches, which may be operated in air, vacuum, liquid insulating media, i.e., mineral oil, and insulating gasses, i.e., SF 6 environment. Direct transfer of electrons from the Fermi level of the metal (cathode) towards the surrounding material is theoretically enabled at very high electric fields as predicted by Fowler and Nordheim for field electron emission from metals into vacuum [2].…”

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confidence: 99%

“…The distribution of the effective contact spots, as well as the effective contact area, depends upon surface geometry, degree of polish, hardness of materials, mechanical pressure, and phase transitions with increasing temperature. The effective contact area is usually smaller than the apparent contact area [6], [7]. However, when an arc forms around the interface this argument may not be valid since field emitted electrons in the surrounding gas increases significantly the effective contact area [7].…”

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Electrostatic Repulsion Between Highly Injecting Metals: An Experimental Investigation

Dervos

1996

Active and Passive Electronic Components

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This paper is an experimental investigation of the major implications brought in the crossing resistance of mechanically contacted metals when operating in the high electronic injection regime, i.e., steady state interfacial voltage values greater than the max. acceptable level determined by specifications and less than the melting voltage. Under such operating conditions, monolayers of positive ions may be formed within interfacial cavities filled by the material from the surrounding space. The dominating ion neutralization process on the cathode controls the formation of "Helmholtz" inner layers at the metal cathode+oxide+gas interface. The presence of a positive ion monolayer over the cathode electrode will tend to reduce the field threshold required for electronic field emission and affect the overall currentvoltage characteristics.The response of contacts operating under high charge injection is monitored on an injected charge vs. interfacial field phase space, which clearly demonstrates non-linear conductivity phenomena and hysteresis effects for the examined structures. Experimental results indicate convincingly the importance of the dielectric media around highly injecting metal contacts. The excessive positive ion formation may also account for the experimentally observed electrostatic repulsion between highly injecting metal contacts. Under low contact pressure situations spontaneous separation of the current carying electrodes may occur. During a spontaneous contact breaking process, the transient current and voltage profiles across the metal contacts have been monitored using state-of-the-art data logging systems. The importance of the oxide capacitance and (time varying) gap capacitance on V(t) and I(t) profiles has been discussed. The obtained results provide evidence for the positive ion layer formation over the cathode electrodes.

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Electric Contacts

Abstract: The support of the management.s of these corporations is gratefully acknowledged. Finally, it is a pleasure to express particular thanks to Springer-Verlag in Berlin, Germany, for t.he kind invitation to write this book, and for the excellent printer's performance.

Cited by 1,526 publications

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An experimental and analytical study of the effect of water and its tribochemistry on the tribocorrosive wear of boundary lubricated systems with ZDDP-containing oil

An experimental and analytical study of the effect of water and its tribochemistry on the tribocorrosive wear of boundary lubricated systems with ZDDP-containing oil

Local Electron Heating in Nanoscale Conductors

Electrostatic Repulsion Between Highly Injecting Metals: An Experimental Investigation

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