Simulations of Nanotribology with Realistic Probe Tip Models

Chandross, Michael; Lorenz, Christian D.; Stevens, Mark J.; Grest, Gary S.

doi:10.1021/la702323y

Cited by 123 publications

(171 citation statements)

References 44 publications

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“…Friction and adhesion of silica are also of fundamental interest for geophysics and earthquake mechanics, since quartz is a common component of rocks and shallow tectonic earthquakes are known to result from frictional instabilities in crustal faults [4,5]. Consequently, it is not surprising that friction of silica has been studied extensively in different contexts [6][7][8][9][10]. One aspect of the silica studies, which is particularly relevant to this paper, is related to the effects of surface chemistry on friction [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Effects of Interfacial Bonding on Friction and Wear at Silica/Silica Interfaces

Liu

Szlufarska

2014

Tribol Lett

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Static friction between amorphous silica surfaces with a varying number of interfacial siloxane (Si-O-Si) bridges was studied using molecular dynamic simulations. Static friction was found to increase linearly with the applied normal pressure, which can be explained in the framework of Prandlt-Tomlinson's model. Friction force was found to increase with concentration of siloxane bridges, but with a decreasing gradient, with the latter being due to interactions between neighboring siloxane bridges. In addition, we identified atomic-level wear mechanisms of silica. These mechanisms include both transfer of individual atoms accompanied by breaking interfacial siloxane bridges and transfer of atomic cluster initialized by rupturing of surface Si-O bonds. Our simulations showed that small clusters are continually formed and dissolved at the sliding interface, which plays an important role in wear at silica/silica interface.

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Section: Introductionmentioning

confidence: 99%

Effects of Interfacial Bonding on Friction and Wear at Silica/Silica Interfaces

Liu

Szlufarska

2014

Tribol Lett

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“…Single-asperity wear simulations (12)(13)(14) and atomic force microscope (AFM) wear experiments (15)(16)(17) challenge the origins of wear debris formation by reporting a gradual atom-by-atom asperity smoothing. This observation further challenges a long-standing question posed by Archard (4,18): When does an asperity collision lead to the formation of a wear debris particle?…”

mentioning

confidence: 99%

On the debris-level origins of adhesive wear

Aghababaei

Warner

Molinari

2017

Proc. Natl. Acad. Sci. U.S.A.

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Every contacting surface inevitably experiences wear. Predicting the exact amount of material loss due to wear relies on empirical data and cannot be obtained from any physical model. Here, we analyze and quantify wear at the most fundamental level, i.e., wear debris particles. Our simulations show that the asperity junction size dictates the debris volume, revealing the origins of the long-standing hypothesized correlation between the wear volume and the real contact area. No correlation, however, is found between the debris volume and the normal applied force at the debris level. Alternatively, we show that the junction size controls the tangential force and sliding distance such that their product, i.e., the tangential work, is always proportional to the debris volume, with a proportionality constant of 1 over the junction shear strength. This study provides an estimation of the debris volume without any empirical factor, resulting in a wear coefficient of unity at the debris level. Discrepant microscopic and macroscopic wear observations and models are then contextualized on the basis of this understanding. This finding offers a way to characterize the wear volume in atomistic simulations and atomic force microscope wear experiments. It also provides a fundamental basis for predicting the wear coefficient for sliding rough contacts, given the statistics of junction clusters sizes.Archard's wear law | adhesive wear | friction | wear debris particle | nanotribology T he study of material loss at sliding surfaces, known as "wear," has over two centuries of history (1). Substantial progress occurred in the mid-1900s with a systematic series of wear experiments that showed, within a certain range of applied load, (i) the wear volume (i.e., total volume of wear debris) is independent of apparent area of contact (2, 3), (ii) the wear rate (i.e., wear volume per sliding distance) is linearly proportional to the macroscopic load acting normal to the interface, i.e., Archard's wear law (3, 4), and (iii) the wear volume is proportional to the frictional work (i.e., the product of frictional force and sliding distance), which was first hypothesized by Reye in 1860 (5) and intermittently discussed and observed experimentally (3,(5)(6)(7)(8). The first observation is commonly rationalized by arguing that the wear process is a direct result of contact between elevated surface asperities and is consequently associated with the real area of contact (2, 3). The second observation can then be understood by noting that the real area of contact is observed to be proportional to the macroscopic normal load (2, 9). The third observation follows from the first two if one assumes a wear volume proportional to sliding distance and a tangential force proportional to normal force (i.e., Amontons' first law of friction) (10).Despite the passage of more than 50 years, these wear relations remain fully empirical, and their microscopic origins are still unclear (11). Single-asperity wear simulations (12-14) and atomic force microscope (AFM...

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“…For example, for a realistic potential energy function, the practical limit on the number of atoms that can be simulated is on the order of tens to hundreds of millions of atoms. 86,88,95 This system size is sufficient to model contact between a surface and the apex of the tip in AFM experiments, 88,94,96 but not the entire tip and remaining system. Naturally, these length scales are also too small to model micro-and macroscale contacts.…”

Section: Future Of Atomistic and Multiscale Modeling Of Nanoscalementioning

confidence: 99%

Review Article: Case studies in future trends of computational and experimental nanomechanics

Tadmor

Kysar

Zimmerman

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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With rapidly increasing numbers of studies of new and exotic material uses for perovskites and quasicrystals, these demand newer instrumentation and simulation developments to resolve the revealed complexities. One such set of observational mechanics at the nanoscale is presented here for somewhat simpler material systems. The expectation is that these approaches will assist those materials scientists and physicists needing to verify atomistic potentials appropriate to the nanomechanical understanding of increasingly complex solids. The five following segments from nine University, National and Industrial Laboratories both review and forecast where some of the important approaches will allow a confirming of how in situ mechanics and nanometric visualization might unravel complex phenomena. These address two-dimensional structures, temporal models for the nanoscale, atomistic and multiscale friction fundamentals, nanoparticle surfaces and interfaces a) Electronic

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Simulations of Nanotribology with Realistic Probe Tip Models

Cited by 123 publications

References 44 publications

Effects of Interfacial Bonding on Friction and Wear at Silica/Silica Interfaces

Effects of Interfacial Bonding on Friction and Wear at Silica/Silica Interfaces

On the debris-level origins of adhesive wear

Review Article: Case studies in future trends of computational and experimental nanomechanics

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