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Surface frictional force

Figure 6.20 Schematic of the centrifuge method to determine adhesion forces of particles on surfaces. Friction forces can also be analyzed when the particles are placed on at a horizontal surface. Figure 6.20 Schematic of the centrifuge method to determine adhesion forces of particles on surfaces. Friction forces can also be analyzed when the particles are placed on at a horizontal surface.
Extrusion can fall into one of two categories direct extrusion and indirect extrusion (Figure 7.17). In direct extrusion a metal billet is placed into a container and driven though a die by a ram, usually attached to a hydraulic press. In indirect extrusion the billet is again placed in a container, but the container end is closed. A hollow ram, carrying a die of the desired shape, is forced into the billet, with the extrusion exiting through the ram Indirect extrusion may occur as a result of die movement or container movement. Because there is no movement between the container wall and billet surface, frictional forces are lower in this method, which reduces the force needed to extrade. There are, however, some limitations on the load that can be applied by the hollow ram. [Pg.264]

Investigations in the past also emphasized the effect of various additives of the slurry on the tribology during CMP [18,19]. It was observed that the presence of a flocculent reduces the surface frictional force (see Fig. 4.9a). Also, the ionic strength of the slurry has a significant impact on the frictional force (shown in Fig. 4.9b). It can be noted from these data that the friction at the surface depends significantly on the chemical interaction at the interface, besides the mechanical aspects. [Pg.91]

In addition to chain molecules confined between two smooth surfaces, frictional forces were studied for grafted chains surrounded by solvent molecules [21] and for chain molecules sheared by topographically nonuniform solid surfaces [33], Tip-based simulations were also carried out to study frictional properties of confined thin films [88-92]. These topics are not covered in this review. [Pg.651]

Atomic force microscopy has been combined with nano-indentation and nano-scratching studies [95]. The hardness (and, to a similar extent, the friction coefficient) of passivated titanium was three to four times higher under in situ conditions, this was assigned to a much faster repassivation process in the presence of the passivating electrolyte solution. Nanotribology, particularly surface friction forces mea-... [Pg.262]

The coefficient of friction /x between two solids is defined as F/W, where F denotes the frictional force and W is the load or force normal to the surfaces, as illustrated in Fig. XII-1. There is a very simple law concerning the coefficient of friction /x, which is amazingly well obeyed. This law, known as Amontons law, states that /x is independent of the apparent area of contact it means that, as shown in the figure, with the same load W the frictional forces will be the same for a small sliding block as for a laige one. A corollary is that /x is independent of load. Thus if IVi = W2, then Fi = F2. [Pg.431]

The force between two adjacent surfaces can be measured directly with the surface force apparatus (SEA), as described in section BT20 [96]. The SEA can be employed in solution to provide an in situ detennination of the forces. Although this instmment does not directly involve an atomically resolved measurement, it has provided considerable msight mto the microscopic origins of surface friction and the effects of electrolytes and lubricants [97]. [Pg.315]

Lateral force microscopy (LFM) has provided a new tool for the investigation of tribological (friction and wear) phenomena on a nanometre scale [110]. Alternatively known as friction force microscopy (FFM), this variant of AFM focuses on the lateral forces experienced by the tip as it traverses the sample surface, which... [Pg.1698]

Klein J ef a/1994 Reduction of frictional forces between solid surfaces bearing polymer brushes Nature 370 634-7... [Pg.1746]

The atomic force microscope (ATM) provides one approach to the measurement of friction in well defined systems. The ATM allows measurement of friction between a surface and a tip with a radius of the order of 5-10 nm figure C2.9.3 a)). It is the tme realization of a single asperity contact with a flat surface which, in its ultimate fonn, would measure friction between a single atom and a surface. The ATM allows friction measurements on surfaces that are well defined in tenns of both composition and stmcture. It is limited by the fact that the characteristics of the tip itself are often poorly understood. It is very difficult to detennine the radius, stmcture and composition of the tip however, these limitations are being resolved. The AFM has already allowed the spatial resolution of friction forces that exlribit atomic periodicity and chemical specificity [3, K), 13]. [Pg.2745]

Ultra-high vacuum (UHV) surface science methods allow preparation and characterization of perfectly clean, well ordered surfaces of single crystalline materials. By preparing pairs of such surfaces it is possible to fonn interfaces under highly controlled conditions. Furthennore, thin films of adsorbed species can be produced and characterized using a wide variety of methods. Surface science methods have been coupled with UHV measurements of macroscopic friction forces. Such measurements have demonstrated that adsorbate film thicknesses of a few monolayers are sufficient to lubricate metal surfaces [12, 181. [Pg.2747]

Lubricants are added to lower interfacial frictional forces between individual particles and/or between particles and fonning die surfaces to improve compaction and ejection (i.e. extraction of the pressed compact from the fonning die). Individual particle surfaces can be lubricated by an adsorbed film that produces a smoother surface and/or decreases interiDarticle attraction. Fonning (die) surfaces can be lubricated by coating with a film of low-viscosity liquid such as water or oil. [Pg.2766]

The net viscous force acting on this volume element is given by the difference between the frictional forces acting on the outer and inner surfaces of the shell ... [Pg.600]

Because fiber frictional properties are so important in the conversion of staple yams to spun yams, ASTM D2612 has been designed to measure the cohesive force encountered in the drafting or fiber alignment of sHver and top under static conditions. This frictional force is affected by surface lubrication, linear density, surface configuration, fiber length, and fiber crimp. [Pg.454]


See other pages where Surface frictional force is mentioned: [Pg.319]    [Pg.675]    [Pg.726]    [Pg.326]    [Pg.245]    [Pg.399]    [Pg.1842]    [Pg.371]    [Pg.86]    [Pg.110]    [Pg.255]    [Pg.346]    [Pg.245]    [Pg.319]    [Pg.675]    [Pg.726]    [Pg.326]    [Pg.245]    [Pg.399]    [Pg.1842]    [Pg.371]    [Pg.86]    [Pg.110]    [Pg.255]    [Pg.346]    [Pg.245]    [Pg.435]    [Pg.436]    [Pg.437]    [Pg.451]    [Pg.830]    [Pg.1710]    [Pg.1710]    [Pg.1712]    [Pg.2742]    [Pg.2742]    [Pg.2743]    [Pg.2745]    [Pg.269]    [Pg.274]    [Pg.369]    [Pg.233]    [Pg.184]    [Pg.333]    [Pg.531]    [Pg.147]    [Pg.454]   
See also in sourсe #XX -- [ Pg.86 ]

See also in sourсe #XX -- [ Pg.86 ]




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