Adhesion hysteresis, and friction

Fig. 26—Connections between adhesion hysteresis and friction on the left the hysteresis results in a relatively large friction, on the right the hysteresis disappears due to introducing decane vapor, which leads to a smaller friction (from Ref. [21]).

Using the SFA technique, it could be demonstrated that there is an intimate relationship between adhesion hysteresis and friction [28, 29, 77]. Both processes dissipate energy through non-equilibrium mechanisms... 

Chaudhury M K and Owen M J 1993 Adhesion hysteresis and friction Langmuir 9 29-31... 

The adhesion hysteresis and its contribution to the friction have been studied extensively by means of SFA [39], which leads to an important conclusion that it is the adhesion hysteresis or the energy loss during the process of approach/separation, rather than the surface energy itself, that dominates the frictional behavior of boundary films. 

Schmitt, F. J., Yoshizawa, H., Schmidt, A., Duda, G., Knoll, W., Wegner, G. and Israelachvili, J., Adhesion energy hysteresis and friction between ultrathin polyglutamate films measured with the surface forces apparatus. Macromolecules, 28, 3401-3410 (1995). 

There appears to be a direct correlation between the three principal forms of elastomeric wear listed earlier and the fundamental and causative frictional mechanisms of adhesion, hysteresis and waves of detachment as shown in Figure 2, thus ... 

Yamada S and Israelachvili J N 1998 Friction and adhesion hysteresis of fluorocarbon surfactant monolayer-coated surfaces measured with the surface forces apparatus J. Rhys. Chem. B 102 234-44... 

The dynamical adhesion process described in this section is also referred to as adhesion hysteresis. We will come back to this subject in later sections when discussing the correlation between adhesion and friction. 

Two conclusions can be drawn from Eqs (24) and (25). First, friction is in direct proportion to the energy difference Ay in the adhesion hysteresis, which is consistent with the experimental results presented in the last section. Secondary, an increase in Dq, namely the mean separation or film thickness, will lead to decrease in friction, which agrees well with the observation in boundary lubrication. If the coefficient s somehow remains fixed, it can be deduced from Eq... 

Amongst different channels of the energy dissipation, the most relevant are the sample viscosity, the contact friction, and the adhesion hysteresis. When the drive frequency is chosen to be CQ0, the power that is dissipated when the tip periodically interacts with the sample can be written as... 

FIG. 18 Schematic of the contact region in the adhesion energy hysteresis [variation of contact radius (r) vs. load (L)] and friction experiments [friction force (F) at constant velocity (V) and load (L)]. The lower inset shows the polyglutamates in an end-on view parallel to the sliding direction. (From Schmitt et al. 1995.)... 

The imderstanding of the ftindamentals of interfacial friction has heen emerging in the last decades, and is in part based on measurements with the surface forces apparatus (109,110). In particular, friction was shown to be related to adhesion hysteresis rather than adhesion itself (110). 

In the contact area between part and counter part elementary friction and wear mechanisms such as adhesion, abrasion, surface fatigue, deformation, elastic hysteresis and damping, tribochemical reactions etc. may occur. These mechanisms are overlapping in the temporal and spatial undetectable real material contact area. In addition highly formulated lubricants, which are mainly used with highly stressed engine elements, exert influence on tribochemical reactions inside and outside of the tribological contact. ... 

In recent years it has been demonstrated that also adhesion (or adhesion hysteresis) plays an important role in friction. Israelachvili and coworkers could show that friction and adhesion hystereses are, in general, directly correlated if certain assumptions are fulfilled. These authors have proposed models based on data obtained by surface forces apparatus (SFA) experiments, e. g. the cobblestone model of interfacial friction (4). In addition, several groups described the application of continuum contact mechanics (e.g. Johnson-Kendall-Roberts (JKR) theory (5)) to describe friction data measured between flat surfaces and nanometer sized contacts (d). 

Nosonovsky M. (2007) Model for solid-liquid and solid-solid friction for rough surfaces with adhesion hysteresis. J Chem Phys 126 224701. 

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