Nanoscratching of iron: A molecular dynamics study of the influence of surface orientation and scratching direction

Gao, Yu; Brodyanski, A.; Kopnarski, Michael; Urbassek, Herbert M.

doi:10.1016/j.commatsci.2015.03.011

Cited by 82 publications

(60 citation statements)

References 37 publications

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“…Above 2.0 GPa for CNO and 1.0 GPa for CND, the friction coefficient increases rapidly with pressure due to increasing indentation of the nanoparticles. This increase in friction coefficient with pressure has been also observed in previous NEMD simulations of hard nanoparticles [33] as well as in nanoscratching simulations of a-iron surfaces by diamond tips [42,43]. This relationship has also been observed experimentally for CNO additives [21,26]; however, other boundary friction experiments have shown increasing wear, but decreasing friction, with increasing pressure [23].…”

Section: Effect Of Normal Pressurementioning

confidence: 47%

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Nonequilibrium Molecular Dynamics Investigation of the Reduction in Friction and Wear by Carbon Nanoparticles Between Iron Surfaces

et al. 2016

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For the successful development and application of novel lubricant additives, a full understanding of their tribological behaviour at the nanoscale is required, but this can be difficult to obtain experimentally. In this study, nonequilibrium molecular dynamics simulations are used to examine the friction and wear reduction mechanisms of promising carbon nanoparticle friction modifier additives. Specifically, the friction and wear behaviour of carbon nanodiamonds (CNDs) and carbon nano-onions (CNOs) confined between a-iron slabs is probed at a range of coverages, pressures, and sliding velocities. At high coverage and low pressure, the nanoparticles do not indent into the a-iron slabs during sliding, leading to zero wear and a low friction coefficient. At low coverage and high pressure, the nanoparticles indent into, and plough through the slabs during sliding, leading to atomic-scale wear and a much higher friction coefficient. This contribution to the friction coefficient is well predicted by an expression developed for macroscopic indentation by Bowden and Tabor. Even at the highest pressures and lowest coverages simulated, both nanoparticles were able to maintain separation of the opposing slabs and reduce friction by approximately 75 % compared to when no nanoparticle was present, which agrees well with experimental observations. CNO nanoparticles yielded a lower indentation (wear) depth and lower friction coefficients at equal coverage and pressure with respect to CND, making them more attractive friction modifier additives. Potential changes in behaviour on harder and softer surfaces are also discussed, together with the implications that these results have in terms of the application of the studied nanoparticles as lubricants additives.

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Section: Effect Of Normal Pressurementioning

confidence: 47%

“…The Lennard-Jones parameters used here, e = 0.02495 eV and r = 3.70, were parameterised for MD simulations of carbon nanotube growth on iron surfaces [41] and have since been successfully applied in tribological NEMD simulations of CNDs between iron surfaces [32] as well as nanoscratching of iron by diamond tips [42,43].…”

Section: Methodsmentioning

confidence: 99%

Nonequilibrium Molecular Dynamics Investigation of the Reduction in Friction and Wear by Carbon Nanoparticles Between Iron Surfaces

et al. 2016

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“…The values of A ind p were determined during the MD simulation following the procedure proposed in Refs. [22,35]. In this approach, only atoms lying within the spherical shell of radius R ?…”

Section: Indentation Stagementioning

confidence: 99%

“…This potential was developed by fitting to the first principle forces obtained in a model liquid configuration and was verified to successively reproduce mechanical and thermal properties of bcc iron. The interaction between Fe and C was described by the purely repulsive Lennard-Jones pair potential with a shifted cutoff radius 4.2 Å [22,27], while the interaction among C-C atom was omitted.…”

Section: Computational Techniquementioning

confidence: 99%

“…Recently, Gao et al [21,22] have systematically studied the nanoscratching of single crystal by carrying out a series of MD simulations using the Mendelev potential and spherical tip. It has been shown that the wear of iron single crystal is significantly influenced by the orientation of the machined surface and the deformation mechanism of the samples during scratching was dominated by dislocation slip and nc-iron [23] In the present work, we investigated the grain size dependence of nanoscratching characteristics with particular focus on the deformation mechanisms coupled to the grain size.…”

Section: Introductionmentioning

confidence: 99%

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Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

et al. 2017

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Using embedded atom method potential, extensive large-scale molecular dynamics (MD) simulations of nanoindentation/nanoscratching of nanocrystalline (nc) iron have been carried out to explore grain size dependence of wear response. MD results show no clear dependence of the frictional and normal forces on the grain size, and the single-crystal (sc) iron has higher frictional and normal force compared to nc-samples. For all samples, the dislocation-mediated mechanism is the primary cause of plastic deformation in both nanoindentation/nanoscratch. However, secondary cooperative mechanisms are varied significantly according to grain size. Pileup formation was observed in the front of and sideways of the tool, and they exhibit strong dependence on grain orientation rather than grain size. Tip size has significant impact on nanoscratch characteristics; both frictional and normal forces monotonically increase as tip radii increase, while the friction coefficient value drops by about 38%. Additionally, the increase in scratch depth leads to an increase in frictional and normal forces as well as friction coefficient. To elucidate the relevance of indentation/scratch results with mechanical properties, uniaxial tensile test was performed for nc-samples, and the result indicates the existence of both the regular and inverse Hall-Petch relations at critical grain size of 110.9 Å . The present results suggest that indentation/scratch hardness has no apparent correlation with the mechanical properties of the substrate, whereas the plastic deformation has.

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Indentation and Scratching on the Nanoscale

Urbassek,

Alabd Alhafez,

Hasse

et al. 2023

Springer Series in Advanced Manufacturing

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Nanoscratching of iron: A molecular dynamics study of the influence of surface orientation and scratching direction

Cited by 82 publications

References 37 publications

Nonequilibrium Molecular Dynamics Investigation of the Reduction in Friction and Wear by Carbon Nanoparticles Between Iron Surfaces

Nonequilibrium Molecular Dynamics Investigation of the Reduction in Friction and Wear by Carbon Nanoparticles Between Iron Surfaces

Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

Indentation and Scratching on the Nanoscale

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