Moisture Effects Including Stiction Resulting From Adsorbed Water Films

1992 ◽  
Vol 114 (1) ◽  
pp. 174-180 ◽  
Author(s):  
Chao Gao ◽  
D. Kuhlmann-Wisldorf ◽  
D. D. Makel
Keyword(s):  
Electrical Contact ◽  
Slow Motion ◽  
Adsorbed Water ◽  
Copper Surface ◽  
Contact Spot ◽  
Electrical Contact Resistance ◽  
Local Pressure ◽  
Water Films ◽  
Moisture Effects ◽  
Contact Spots

Stiction resulting from moisture effects at small elastic contact spots has been identified and studied using bundles of fine, gold-plated copper fibers sliding on a gold-plated copper surface. The relevant measurements were made in the hoop apparatus which permits simultaneous monitoring of the momentary coefficient of friction and electrical contact resistance. Previous studies made with the hoop apparatus have shown that under the action of high local pressure, adsorbed moisture is expelled from between the contact spots leaving only one monomolecular layer of adsorbed water on each of the contacting surfaces. Additional details of the observations are varied and permit a refined analysis. Stiction results during periods of very slow motion or rest through local energy reduction at the spots as excess water is slowly drained in the course of molecular ordering of the two absorbed layers. Complex variations of kinetic friction with humidity and sliding speed are explained through the interplay of excess molecules between the contact spot surfaces, meniscus formation, fluid drag about the spots, and shear thinning in that flow.

Sliding Characteristics in the Copper Contacts

1993 ◽  
Vol 5 (3) ◽  
pp. 292-298
Author(s):  
Yoshitada Watanabe ◽  
Keyword(s):  
Contact Resistance ◽  
Coefficient Of Friction ◽  
Heat Generation ◽  
Electrical Contact ◽  
Rotational Frequency ◽  
Contact Spot ◽  
Electrical Contact Resistance ◽  
The Coefficient Of Friction ◽  
Contact Surfaces ◽  
Sliding Test

A low rotational frequency sliding tester which could measure electrical contact resistance and coefficient of friction simultaneously was trially fabricated. Relations between electrical contact resistance and coefficients of friction were investigated by making sliding test on clean copper and surface oxidized copper contacts respectively, which were used relatively frequently in industries. As far as the measurement work made this time, of which rotational frequency was low, was concerned, it was found that the heat generation due to mechanical friction was low and the heat generation due to Joule's heat in the case of sliding clean contact surfaces was also low because of low contact resistance. It was, however, found that CU²0, etc. were formed due to rapid progress of oxidation by the generation of Joule's heat at the contact surfaces, of which real contact areas were extremely small, being roughened along with the increase of the sliding frequency. On the other hand, it was further found that although the existence of oxides in advance at the sliding surface extremely lowered the coefficient of friction (0.07 for example) in which the oxidized film indicating contrarily (70mΩ for example). It was presumed that formations and destroys of oxidation film were repeated by flow of electric current at the contact spot to cause Fritting Phenomenon.

Friction, Wear, and Interfacial Electrical Resistance. Part I: The Hoop Apparatus

1987 ◽  
Vol 109 (4) ◽  
pp. 604-608 ◽  
Author(s):  
D. Kuhlmann-Wilsdorf ◽  
Y. J. Chang ◽  
L. B. Johnson ◽  
L. J. Bredell
Keyword(s):  
Coefficient Of Friction ◽  
Electrical Resistance ◽  
Electrical Contact ◽  
Constant Load ◽  
Simultaneous Recording ◽  
Contact Spot ◽  
Interfacial Resistance ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Contact Spots

An apparatus has been developed for the gathering of data from which, through suitable analysis, detailed information on the momentary condition of a sliding interface may be obtained. The information includes the number of the contact spots, the electrical resistivity of the interfacial film, and the flash temperature at the contact spots. The apparatus provides for the continuous simultaneous recording of the coefficient of friction and of the interfacial electrical resistance of a slider in stick-slip motion at constant load and controllable average speed, and/or of the interfacial resistance of a slider at constant speed under controllable load. Loads between 0.3 and 10N and speeds up to 0.15m/s may be selected, in a variety of atmospheres and ambient pressures, as the apparatus is enclosed in a bell jar. It consists of a rotating cylindrical metal hoop inside of which a metal slider moves under the forces of friction and gravity, giving stick-slip behavior full play, and a slider in fixed position subjected to controllable, hydrostatically applied loads. The entire apparatus can be used with a controlled atmosphere or vacuum. The motion of the stick-slip slider, from which the coefficient of friction is inferred, is recorded on one pen of a three-pen strip-chart recorder and the electrical contact resistances between the two sliders and the hoop on the other two pens. The dependence of contact resistance on load, obtainable from the fixed slider without removing the bell jar, permits a determination of the number of contact spots provided the constriction resistance is not negligibly small compared to the film resistance. Deliberate changes of the contact spot temperature can be made by adjusting the current through the slider/hoop interfaces.

Experiments on, and a Two-Component Model for, the Behavior of Water Nano-Films on Metals

1990 ◽  
Vol 188 ◽  
Author(s):  
Chao Gao ◽  
D. Kuhlmann-Wilsdorf
Keyword(s):  
Contact Resistance ◽  
Coefficient Of Friction ◽  
Molecular Layer ◽  
Adsorbed Water ◽  
Solid Substrate ◽  
Contact Spot ◽  
Component Model ◽  
Fiber Bundles ◽  
Two Component ◽  
Contact Spots

ABSTRACTBy means of the hoop apparatus, contact resistance and coefficient of friction of fiber bundles on a solid substrate have been determined in air at different humidities. The results can be explained by a two-component model, comprising (i) a double molecular layer of adsorbed water at contact spots and (ii) a zone about each contact spot within which excess adsorbed moisture which has been squeezed out from the load-bearing area bypasses the spot.

scholarly journals Simulation and experimental investigation of contact spot temperature for electrical contact components

2021 ◽  
Vol 1207 (1) ◽  
pp. 012021
Author(s):  
Chao Zhang ◽  
Zien Zhao ◽  
Wanbin Ren
Keyword(s):  
Contact Resistance ◽  
Electrical Contact ◽  
Element Model ◽  
Contact Spot ◽  
Comsol Multiphysics ◽  
Film Resistance ◽  
Test Rig ◽  
Electrical Contact Resistance ◽  
Electrical Connections ◽  
Spot Temperature

Abstract The contact spot temperature of electrical contact components substantially affects the reliability and electrical life of any electrical connections within the electrical engineering. In this paper, finite element model of typical spring structure components is built by using COMSOL Multiphysics software. Furthermore, the transient process of contact temperature is simulated by taking account of film resistance on the contact surface. Moreover, a test rig is introduced that makes it possible to measure the electrical contact resistance and temperature within the electrical contact components simultaneously. Finally, correlation between contact resistance and contact spot temperature with different contact force and current levels are investigated explicitly.

scholarly journals The Route for Ultra-High Recording Density Using Probe-Based Data Storage Device

NANO ◽  
2015 ◽  
Vol 10 (08) ◽  
pp. 1550118 ◽  
Author(s):  
Lei Wang ◽  
Jing Wen ◽  
CiHui Yang ◽  
Shan Gai ◽  
YuanXiu Peng
Keyword(s):  
Phase Change ◽  
Data Storage ◽  
Electrical Contact ◽  
Crystal Nucleation ◽  
Access Time ◽  
Storage Device ◽  
Electrical Contact Resistance ◽  
Low Energy Consumption ◽  
Modeling Techniques ◽  
Second Period

Phase-change probe memory using Ge2Sb2Te5 has been considered as one of the promising candidates as next-generation data storage device due to its ultra-high density, low energy consumption, short access time and long retention time. In order to utmostly mimic the practical setup, and thus fully explore the potential of phase-change probe memory for 10 Tbit/in2 target, some advanced modeling techniques that include threshold-switching, electrical contact resistance, thermal boundary resistance and crystal nucleation-growth, are introduced into the already-established electrothermal model to simulate the write and read performance of phase-change probe memory using an optimal media stack design. The resulting predictions clearly demonstrate the capability of phase-change probe memory to record 10 Tbit/in2 density under pico Joule energy within micro second period.

Discrete drops in the electrical contact resistance during nanoindentation of a bulk metallic glass

2016 ◽  
Vol 108 (18) ◽  
pp. 181903 ◽  
Author(s):  
Gaurav Singh ◽  
R. L. Narayan ◽  
A. M. Asiri ◽  
U. Ramamurty
Keyword(s):  
Metallic Glass ◽  
Contact Resistance ◽  
Bulk Metallic Glass ◽  
Electrical Contact ◽  
Electrical Contact Resistance
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