Screened empirical bond-order potentials for Si-C

Pastewka, Lars; Klemenz, Andreas; Gumbsch, Peter; Moseler, Michael

doi:10.1103/physrevb.87.205410

Cited by 121 publications

(104 citation statements)

References 106 publications

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“…Accordingly, the configuration of all simulations discussed here was chosen so that the junction size leads to wear debris formation. A set of 2D (19) and newly developed 3D model interatomic potentials and a recently developed diamond potential (20) are used. The formation process of 3D wear particles is simulated and analyzed.…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

“…19). For diamond simulations using multimillion atoms, the Tersoff potential (45), enhanced with a screening function (20) for modeling brittle bond breaking, is used. Potential parameters and corresponding physical properties are taken from ref.…”

Section: Methodsmentioning

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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“…Provided a suitable potential energy function is employed, MD simulation is a powerful research tool to understand the tribology, plasticity and wear behaviour of a range of materials [26][27][28][29]. Accordingly, the newly proposed potential energy function (a screened version [15] of the Si-II (silicon) developed by Erhart et al [14]) was used in this study. Prior to use, we performed several tests to ensure its robustness by reproducing the elastic constants and other relevant mechanical properties of both silicon and diamond.…”

Section: Simulation Setup and Potential Functionmentioning

confidence: 99%

“…Further details of the MD simulation model are shown in Table III for the purpose of reproducibility. Si-C interatomic potential function Screening function [15] applied to Si-II (elemental silicon) parameters of Erhart et al [14] Cutting tool (rake and clearance angle)…”

Section: Simulation Setup and Potential Functionmentioning

confidence: 99%

“…This shortcoming of the potentials used in the past raises questions about previously performed MD studies of nanometric cutting processes. Pastewka et al [15] recently developed an improved screened cutoff scheme, which extends the range of these potentials to overcome the described limitations. These new, screened potential formulations, which will be used in this simulation study, correctly describe the brittle materials response and improved description of amorphous phases.…”

Section: Introductionmentioning

confidence: 99%

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Influence of microstructure on the cutting behaviour of silicon

et al. 2016

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General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Abstract:We use molecular dynamics simulation to study the mechanisms of plasticity during cutting of monocrystalline and polycrystalline silicon. Three scenarios are considered: (i) cutting a single crystal silicon workpiece with a single crystal diamond tool, (ii) cutting a polysilicon workpiece with a single crystal diamond tool, and (iii) cutting a single crystal silicon workpiece with a polycrystalline diamond tool. A long-range analytical bond order potential is used in the simulations, providing a more accurate picture of the atomic-scale mechanisms of brittle fracture, ductile plasticity, and structural changes in silicon. The MD simulation results show a unique phenomenon of brittle cracking typically inclined at an angle of 45° to 55° to the cut surface, leading to the formation of periodic arrays of nanogrooves in monocrystalline silicon, which is a new insight into previously published results. Furthermore, during cutting, silicon is found to undergo solid-state directional amorphisation without prior Si-I to Si-II (beta tin) transformation, which is in direct contrast to many previously published MD studies on this topic. Our simulations also predict that the propensity for amorphisation is significantly higher in single crystal silicon than in polysilicon, signifying that grain boundaries eases the material removal process.

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Tetrahedral Amorphous Carbon Coatings for Friction Reduction of the Valve Train in Internal Combustion Engines

et al. 2014

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Tetrahedral amorphous carbon (ta-C) is studied as a tribological coating for the valve train's exhaust camshaft of a combustion engine. The coated camshafts were installed in a non-fired engine, tested in a computerized component test bench under practice-relevant conditions and analyzed for their frictional behavior. A notable reduction of the valve train's drive torque on the test bench is demonstrated. Namely, on a roller cam system with ta-C-coated camshaft the reduction is about 15% in average within the entire engine-map. The ta-C coatings were extensively characterized under laboratory conditions before and after the investigations on the test bench. Mechanistic understanding of the tribological behavior of ta-C coatings under dry or starving lubricated conditions was achieved by atomistic simulations of the tribological contact. Industrial utilization of these results would lead to a significant increase of the energy efficiency of combustion engines.

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Screened empirical bond-order potentials for Si-C

Cited by 121 publications

References 106 publications

On the debris-level origins of adhesive wear

On the debris-level origins of adhesive wear

Influence of microstructure on the cutting behaviour of silicon

Tetrahedral Amorphous Carbon Coatings for Friction Reduction of the Valve Train in Internal Combustion Engines

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