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.

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.

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.

Radiometric Chronology of Neh–nar Glacier, Kashmir

1982 ◽  
Vol 28 (98) ◽  
pp. 91-105 ◽  
Author(s):  
V. N. Nijampurkar ◽  
N. Bhandari ◽  
C. P. Vohra ◽  
V. Krishnan
Keyword(s):  
Average Rate ◽  
Component Model ◽  
Vertical Profiles ◽  
Kashmir Valley ◽  
Movement Rate ◽  
Accumulation Zone ◽  
Core Samples ◽  
Surface Samples ◽  
Two Component

AbstractSurface and core samples of Neh–nar Glacier in the Kashmir Valley have been analysed for the radionuclides 32Si. 210Pb, 40K, and 137Cs. The lateral and vertical profiles (at an altitude of about 4 140 m) reveal:(1)32Si activity decreasing slowly from the accumulation zone to 4 050 m altitude and then abruptly towards the snout.(2)Five zones of alternating high and low 210Pb activity in the surface samples.(3)An horizon at between 2 and 3 m depth containing 210Pb activity above natural levels. This horizon is also associated with 137Cs and a maximum in total ß activity.The ice samples have been dated on the basis of a simplified two–component model, the “fresh“contribution determined by 2l0Pb and the old component by 32Si. The following conclusions can be drawn from these observations:(1)The model age of the snout ice is c. 850 years.(2)The average rate of ice movement in the lower glacier is about 2 m/year, which compares well with the annual movement rate of 2.65 m/year observed since 1974.

scholarly journals Estimation of Galactic Model Parameters by Interval Method

1996 ◽  
Vol 169 ◽  
pp. 713-714
Author(s):  
S. A. Kutuzov
Keyword(s):  
Mutual Interaction ◽  
Component Model ◽  
Model Parameters ◽  
Interval Method ◽  
Two Component ◽  
The Galaxy ◽  
Galactic Model

The interval method of estimating model parameters (MPs) for the Galaxy was suggested earlier (Kutuzov 1988). Intervals are proposed to be used both for observational estimates of galactic parameters (GPs) and for the values of MPs. In this work we consider a model as a tool for studying mutual interaction of GPs. Two-component model is considered (Kutuzov, Ossipkov 1989). We have to estimate the array P of eight MPs.

scholarly journals A Two‐Component Model for the Light Curves of Hypernovae

2003 ◽  
Vol 593 (2) ◽  
pp. 931-940 ◽  
Author(s):  
Keiichi Maeda ◽  
Paolo A. Mazzali ◽  
Jingsong Deng ◽  
Ken’ichi Nomoto ◽  
Yuzuru Yoshii ◽  
...  
Keyword(s):  
Light Curves ◽  
Component Model ◽  
Two Component

Two-Component Model of Chemyon-Oriented Behaviors in Korea

2002 ◽  
Vol 33 (3) ◽  
pp. 332-345 ◽  
Author(s):  
Sang-Chin Choi ◽  
Suk-Jae Lee
Keyword(s):  
Component Model ◽  
Two Component

Rotation of a two-component model neutron star in the GTR

Astrophysics ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 260-266 ◽  
Author(s):  
D. M. Sedrakian
Keyword(s):  
Neutron Star ◽  
Component Model ◽  
Two Component
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