Anisotropy of frictional forces in muscovite mica

Hirano, Motohisa; Shinjo, Kazumasa; Kaneko, Reizo; Murata, Yoshitada

doi:10.1103/physrevlett.67.2642

Cited by 342 publications

(198 citation statements)

References 14 publications

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“…Thus in contradiction with the analytic models, they observe a significant static friction at the misoriented interface; however, the reason for this anisotropy was not clear. This result differs from measurements on mica surfaces, where Hirano et al 7 found that the friction force anisotropy depends strongly on the ''lattice misfit angle.' ' Robbins et al recently used molecular dynamics ͑MD͒ simulations to study the origin of static friction anisotropy, and proposed that the absorption of a ''third body,'' such as small hydrocarbon molecules, can cause the nonvanishing static friction between two macroscopic objects.…”

Section: Introductioncontrasting

confidence: 55%

Friction anisotropy at Ni(100)/(100) interfaces: Molecular dynamics studies

Qi¹,

Cheng²,

Çağın

et al. 2002

Phys. Rev. B

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The friction of surfaces moving relative to each other must derive from the atomic interaction at interfaces. However, recent experiments bring into question the fundamental understanding of this phenomenon. The analytic theories predict that most perfect clean incommensurate interfaces would produce no static friction, whereas commensurate aligned surfaces would have very high friction. In contrast recent experiments show that the static friction coefficient between clean but 45°misoriented Ni͑001͒ surfaces is only a factor of 4 smaller than for the aligned surfaces ( ϳ0°) and clearly does not vanish ͑ is defined as the rotation angle between the relative crystallographic orientations of two parallel surfaces͒. To understand this friction anisotropy and the difference between analytic theory and experiment, we carried out a series of nonequilibrium molecular dynamics simulations at 300 K for sliding of Ni͑001͒/Ni͑001͒ interfaces under a constant shear force. Our molecular dynamics calculations on interfaces with the top layer roughed ͑and rms roughness of 0.8 Å͒ lead to the static frictional coefficients in good agreement with the corresponding experimental data. On the other hand, perfect smooth surfaces ͑rms roughness of 0 Å͒ lead to a factor of 34 -330 decreasing of static friction coefficients for misaligned surfaces, a result more consistent with the analytic theories. This shows that the major source of the discrepancy is that small amounts of roughness dramatically increase the friction on incommensurate surfaces, so that misaligned directions are comparable to aligned directions.

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Section: Introductioncontrasting

confidence: 55%

Friction anisotropy at Ni(100)/(100) interfaces: Molecular dynamics studies

Qi¹,

Cheng²,

Çağın

et al. 2002

Phys. Rev. B

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“…Over an intermediate range of corrugations, the two surfaces slide freely in some alignments and are pinned in others. This extreme dependence on relative alignment has not been seen in experiments, but strong orientational variations in friction have been seen between mica surfaces (Hirano et al, 1991) and between a crystalline AFM tip and substrate (Hirano et al, 1997).…”

Section: A Effect Of Commensurabilitymentioning

confidence: 92%

Computer Simulations of Friction, Lubrication, and Wear

Robbins¹,

Müser²

2000

Mechanics &Amp; Materials Science

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Computer simulations have played an important role in understanding tribological processes. They allow controlled numerical "experiments" where the geometry, sliding conditions and interactions between atoms can be varied at will to explore their effect on friction, lubrication, and wear. Unlike laboratory experiments, computer simulations enable scientists to follow and analyze the full dynamics of all atoms. Moreover, theorists have no other general approach to analyze processes like friction and wear. There is no known principle like minimization of free energy that determines the steady state of non-equilibrium systems. Even if there was, simulations would be needed to address the complex systems of interest, just as in many equilibrium problems.Tremendous advances in computing hardware and methodology have dramatically increased the ability of theorists to simulate tribological processes. This has led to an explosion in the number of computational studies over the last decade, and allowed increasingly sophisticated modeling of sliding contacts. Although it is not yet possible to treat all the length scales and time scales that enter the friction coefficient of engineering materials, computer simulations have revealed a great deal of information about the microscopic origins of static and kinetic friction, the behavior of boundary lubricants, and the interplay between molecular geometry and tribological properties. These results provide valuable input to more traditional macroscopic calculations. Given the rapid pace of developments, simulations can be expected to play an expanding role in tribology.In the following chapter we present an overview of the major results from the growing simulation literature. The emphasis is on providing a coherent picture of the field, rather than a historical review. We also outline opportunities for improved simulations, and highlight unanswered questions.We begin by presenting a brief overview of simulation techniques and focus on special features of simulations for tribological processes. For example, it is well known that the results of tribological experiments can be strongly influenced by the mechanical properties of the entire system that produces sliding. In much the same way, the results from simulations depend on how relative motion of the surfaces is imposed, and how heat generated by sliding is removed. The different techniques that are used are described, so that their influence on results can be understood in later sections.The complexities of realistic three-dimensional systems can make it difficult to analyze the molecular mechanisms that underly friction. The third section focuses on dry, wearless friction in less complex systems. The discussion begins with simple one-dimensional models of friction between crystalline surfaces. These models illustrate general results for the origin and trends of static and kinetic friction, such as the importance of metastability and the effect of commensurability. Then two-dimensional studies are described, with an emphasis ...

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“…21 Finally, regarding friction at the atomic level, Hirano et al have measured anisotropy in the friction force between two mica surfaces. 22 The authors found that the friction force depends on the misorientation angle of the contacting surfaces. The friction decreases when the lattice mismatch between the surfaces increases.…”

Section: Introductionmentioning

confidence: 99%

Simulations of atomic-scale sliding friction

1996

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Simulation studies of atomic-scale sliding friction have been performed for a number of tip-surface and surface-surface contacts consisting of copper atoms. Both geometrically very simple tip-surface structures and more realistic interface necks formed by simulated annealing have been studied. Kinetic friction is observed to be caused by atomic-scale stick and slip which occurs by nucleation and subsequent motion of dislocations preferably between close-packed ͕111͖ planes. Stick and slip seems to occur in different situations. For single crystalline contacts without grain boundaries at the interface the stick and slip process is clearly observed for a large number of contact areas, normal loads, and sliding velocities. If the tip and substrate crystal orientations are different so that a mismatch exists in the interface, the stick and slip process is more fragile. It is then caused by local pinning of atoms near the boundary of the interface and is therefore more easily observed for smaller contacts. Depending on crystal orientation and load, frictional wear can also be seen in the simulations. In particular, for the annealed interface necks which model contacts created by scanning tunneling microscope/ atomic force microscope tip indentations the sliding process involves breaking contacts leaving tip material behind on the substrate.

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Anisotropy of frictional forces in muscovite mica

Cited by 342 publications

References 14 publications

Friction anisotropy at Ni(100)/(100) interfaces: Molecular dynamics studies

Friction anisotropy at Ni(100)/(100) interfaces: Molecular dynamics studies

Computer Simulations of Friction, Lubrication, and Wear

Simulations of atomic-scale sliding friction

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