Electrical performance of contaminated rough surfaces in contact

Kogut, Lior

doi:10.1063/1.1914954

Cited by 37 publications

(21 citation statements)

References 32 publications

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“…Nevertheless, the results in Figure 8, which at a constant applied load, show that with an increased electrical current density, temperature, and rotating speed, the contact resistance decreases for all the tests, except for the tests at 80°C and 5000 or 10,000 RPM. The decrease in the contact resistance can also connect with an increase in the electrical conduction area, 25 and a decrease in the brush stiffness with an increase in the temperature. 12 At the same time, additional open circuits become closed circuits and increase the real contact area.…”

Section: Resultsmentioning

confidence: 99%

Electrical contact resistance and wear of a dynamically excited metal–graphite brush

Turel

Slavič

Boltežar

2017

Advances in Mechanical Engineering

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The wear and contact resistance of sliding contacts are typically researched with a pin-on-disk experiment that prevents dynamic excitation. However, in electrical machines, the brush clearance enables dynamic excitation, resulting in flexible body dynamics. To research the wear and contact resistance during dynamical excitation, an in-situ experimental approach is introduced here, with the influences of rotational speed, electrical current, and temperature being assessed. This research shows that a small wear rate and contact resistance are possible at 10,000 and 5000 RPM if the electrical current is higher than 3 A. It was also found that the contact resistance decreased with an increased ambient temperature, electrical current, and rotating speed, whereas the wear rate increased with the rotating speed at low current density and low ambient temperature.

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Section: Resultsmentioning

confidence: 99%

Electrical contact resistance and wear of a dynamically excited metal–graphite brush

Turel

Slavič

Boltežar

2017

Advances in Mechanical Engineering

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“…[9] Two electric potentials of 0.1 and 0.5 V were used for comparison, and ε is 0.4 nm. It can be seen from Fig.…”

Section: A Comparative Analysis Among Various Adhesive Forcesmentioning

confidence: 99%

Interfacial properties for real rough MEMS/NEMS surfaces by incorporating the electrostatic and Casimir effects–a theoretical study

Xie

Ding

Liu

et al. 2009

Surface & Interface Analysis

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This paper studied the adhesive properties of real rough micro/nano-electromechanical systems (MEMS/NEMS) surfaces by considering the electrostatic force and the Casimir force theoretically, and an improved model has been proposed. A statistical approach for characterizing surface topography was used by taking the surface standard deviation, the asperity density and the radius of curvature into account. The effects of surface roughness on the electrostatic force and the Casimir force were analysed individually, and a comparison between the proposed model and existing models has been conducted. The whole adhesive force increases with the surface standard deviation, and the prediction by the proposed model becomes more in agreement with the one by existing models when the surface standard deviation is increased. The contribution of the Casimir force to the total adhesive force tends to vanish when the surface standard deviation is relatively large. The electrostatic force and the Casimir force contribute more to the total adhesive forces calculated based on the proposed model with the increase of the asperity density and the radius of curvature. Copyright c 2009 John Wiley & Sons, Ltd. Keywords: MEMS/NEMS; interfacial properties; electrostatic force; Casimir force; theoretical analysisAdhesion is a serious problem specific to micro/nanoelectromechanical systems (MEMS/NEMS) due to their large surface area-to-volume ratio. The study on adhesion problems is of great importance to the normal operation and resolving the tribological problems in static micro-components (e.g. microbeams) and dynamic devices (e.g. rotors in micro-motors). [1 -4] A lot of attention has been given to the adhesion behaviour of smooth surfaces in earlier years, and increasingly more studies have been conducted for MEMS surfaces with rough features since real micro-components possess some roughness, and configurations of multi-asperities exist universally in MEMS systems. [5,6] Although the roughness of some devices is on the nanoscale, its effect on adhesion is still significant due to the influence of surface and size effect. [7] Hence, to investigate the adhesion problems based on real rough surfaces is more meaningful from practical perspectives. [8,9] It has been revealed that surface energies and related surface forces (e.g. van der Waals (VDW) force and electrostatic force, etc.) are the key factors in determining the adhesive and contact deformations. Real contact area tends to increase and the contact deformation could set in due to the presence of surface forces. [3,10,11] Two earlier theories of adhesion models for the contact between an elastic sphere and a flat surface have been proposed: one is the Johnson-Kendall-Roberts (JKR) model proposed by Johnson et al. [12] and the model can be applied to soft materials with a larger contact curvature and a higher adhesion energy, e.g. rubber; the other is the Derjaguin-MullerToporov (DMT) model which can be applied to hard materials with a smaller contact curvature and a lower adhesion ...

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“…The crystalline parameter of NiO, the main oxide for the Au-Ni contact, is about 0.4 nm [17], so the thickness of oxide film is defined from 1 nm to 6 nm in the modeling. 6 nm is chosen as it was suggested that no tunnel effect could occur for the thickness larger than 5 nm [11].…”

Section: B Assumptions Of Insulating Filmmentioning

confidence: 99%

“…-If the film was damaged, the tunnel effect became very weak compared to that of an intact film, and the I-V curves kept Ohmic [11].…”

Section: Introductionmentioning

confidence: 99%

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Finite element modeling of nickel oxide film for Au-Ni contact of MEMS switches

Liu

Leray

Colin

et al. 2015

2015 IEEE 61st Holm Conference on Electrical Contacts (Holm)

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Abstract-Contamination and oxidation are inevitable in contact surfaces, especially for micro contact under low load (μN-mN). They are considered as major causes for a high contact resistance, and can lead to the failure of a contact. However, as the film formation is complicated, also it is difficult to accurately observe and measure them, the characterization of the films is not well known. In the paper, a finite element model of nickel oxide film is developed for Au-Ni contact of MEMS switches. Considering the fact that the electrical contact area is only a portion of the mechanical contact area, a model featured 'nanospots' is developed: multiple small conductive spots are scattered in a big mechanical contact asperity, and ultrathin oxide film is around the nano-spots. The size of electrical spots and mechanical asperity is calculated based on the measured electrical resistance and mechanical contact modeling respectively. The simulations results show a good match with the experimental results. This model allows us to determine some possible geometry configuration that leads to the measured contact resistance in real devices.

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Electrical performance of contaminated rough surfaces in contact

Cited by 37 publications

References 32 publications

Electrical contact resistance and wear of a dynamically excited metal–graphite brush

Electrical contact resistance and wear of a dynamically excited metal–graphite brush

Interfacial properties for real rough MEMS/NEMS surfaces by incorporating the electrostatic and Casimir effects–a theoretical study

Finite element modeling of nickel oxide film for Au-Ni contact of MEMS switches

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