Static friction interfaces

Another mechanism of static friction suggests that when two surfaces are pressed together under a normal load, the atoms or molecules at the interface will rearrange themselves to minimize the energy and to form localized junctions called cold welding, which is often observed in contacts... 

Self emulsifying lubricant for 2 for 1 twisting. Particularly suitable for application from a sintered interface on in-line lubricators. Imparts very low dynamic yarn/solid friction for trouble free high speed processing and controlled yarn/yarn static friction for good package stability. 

Note of the author The above ASTM procedure indicated (1. Scope) that the test method is not intended for use on wet surfaces. This follows from the definition of the static coefficient of friction according to which the two surfaces should be in direct contact with each other, and nothing, including water, should be between them, on the interface. Therefore, by NBS definition (US National Bureau of Standards, now National Institnte of Standards and Technology), all static friction meters mnst be nsed on dry, clean snrfaces. Formally, static coefficient of friction cannot be determined on a wet deck. That is why the ASTM standard F 1679, described below, and applicable to wet snrfaces, does not mention coefficient of friction, but only slip resistance and slip index. 

When two solid objects are in contact under a normal load W, a certain finite amount of force will be required to initiate and maintain tangential movement with respect to one another. When at rest, no recoverable energy is stored at the interface between the two, so that when force is applied and work is done, most of that work is dissipated as heat. The force which must be overcome in order to make the two objects move is known generally as friction. In general, one finds that two frictional forces will be involved in such a process the force necessary to initiate movement or that to overcome static friction, and that necessary to maintain movement or kinetic friction. 

Dragoni, E., Mauri, P., 2000. Intrinsic static strength of friction interfaces augmented with anaerobic adhesives. Int. J. Adhes. Adhes. 20 (4), 315-321,... 

Another velocity finally appears in a system where a liquid is in contact with an interface. The interface energy 7 then works as a static driving force. This can trigger a current which is damped by a dynamic force, the viscous friction, in the case of density difference between crystal and liquid. Taking the ratio... 

The static - double-layer effect has been accounted for by assuming an equilibrium ionic distribution up to the positions located close to the interface in phases w and o, respectively, presumably at the corresponding outer Helmholtz plane (-> Frumkin correction) [iii], see also -> Verwey-Niessen model. Significance of the Frumkin correction was discussed critically to show that it applies only at equilibrium, that is, in the absence of faradaic current [vi]. Instead, the dynamic Levich correction should be used if the system is not at equilibrium [vi, vii]. Theoretical description of the ion transfer has remained a matter of continuing discussion. It has not been clear whether ion transfer across ITIES is better described as an activated (Butler-Volmer) process [viii], as a mass transport (Nernst-Planck) phenomenon [ix, x], or as a combination of both [xi]. Evidence has been also provided that the Frumkin correction overestimates the effect of electric double layer [xii]. Molecular dynamics (MD) computer simulations highlighted the dynamic role of the water protrusions (fingers) and friction effects [xiii, xiv], which has been further studied theoretically [xv,xvi]. 

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