Hertzian stress contribution to low friction behavior of thin MoS2 coatings

Singer, I. L.; Bolster, R.N.; Wegand, John; Fayeulle, S.; Stupp, Bernard C.

doi:10.1063/1.104276

Cited by 233 publications

(140 citation statements)

References 18 publications

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“…The process was carried out for densities ranging from 2.7 to 3.4g/cm 3 , leading to different energies. We found that lower cooling rates decrease the energy of DLC structures, leading to stable DLC structures with densities of 3.0 to 3.3g/cm 3 . In this study, we discuss the 3.24 g/cc system (the experimental value).…”

Section: The Atomistic Structure Of Bulk Ta-c Dlcmentioning

confidence: 93%

“…This simplified model assumes that the real contact area corresponds to the Hertzian zone, as calculated in equation (3). This assumption has been verified for soft and very thin interface films that lead to good accommodation in the contact geometry.…”

Section: Survey On Extremely Low Friction Under Boundary Lubricationmentioning

confidence: 99%

“…Therefore, friction measurements at different normal loads can be useful to determine S 0 and α values in a given tribological system. However, equation (3) indicates that the minimum friction coefficient value is α so that the friction cannot vanish completely. For example friction experiments performed on MoS 2 coatings under different atmospheres [4][5][6][7][8] have led to α =0.001.…”

Section: Survey On Extremely Low Friction Under Boundary Lubricationmentioning

confidence: 99%

“…It is plausible that friction between H-terminated carbon surfaces would be low because the C-H/C-H interface has a low binding energy of 0.08 eV per bond. According to the model in equation (3), the shear strength of 10 MPa expected for such a system would lead to a steady-state friction coefficient lower than 0.01 [14].…”

Section: Superlubricity Of Mos 2 and Dlcmentioning

confidence: 99%

“…The shear strength S of solids at high pressure is generally observed to be pressure dependent, which can be approximated by [2]: S = S 0 + αP (2) According to the Hertzian contact theory (below the elastic limits), and in the sphere-on-plane configuration, the friction coefficient µ depends of three variables as [3]:…”

Section: Survey On Extremely Low Friction Under Boundary Lubricationmentioning

confidence: 99%

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Superlubricity mechanism of diamond-like carbon with glycerol. Coupling of experimental and simulation studies

Bouchet

Matta

Le-Mogne

et al. 2007

J. Phys.: Conf. Ser.

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Abstract. We report a unique tribological system that produces superlubricity under boundary lubrication conditions with extremely little wear. This system is a thin coating of hydrogen-free amorphous Diamond-Like-Carbon (denoted as ta-C) at 353 K in a ta-C/ta-C friction pair lubricated with pure glycerol. To understand the mechanism of friction vanishing we performed ToF-SIMS experiments using deuterated glycerol and 13 C glycerol. This was complemented by first-principlesbased computer simulations using the ReaxFF reactive force field to create an atomistic model of ta-C. These simulations show that DLC with the experimental density of 3.24 g/cc leads to an atomistic structure consisting of a 3D percolating network of tetrahedral (sp 3 ) carbons accounting for 71.5% of the total, in excellent agreement with the 70% deduced from our Auger spectroscopy and XANES experiments. The simulations show that the remaining carbons (with sp 2 and sp 1 character) attach in short chains of length 1 to 7. In sliding simulations including glycerol molecules, the surface atoms react readily to form a very smooth carbon surface containing OH-terminated groups. This agrees with our SIMS experiments. The simulations find that the OH atoms are mostly bound to surface sp 1 atoms leading to very flexible elastic response to sliding. Both simulations and experiments suggest that the origin of the superlubricity arises from the formation of this OH-terminated surface.

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Section: The Atomistic Structure Of Bulk Ta-c Dlcmentioning

confidence: 93%

Section: Survey On Extremely Low Friction Under Boundary Lubricationmentioning

confidence: 99%

Section: Survey On Extremely Low Friction Under Boundary Lubricationmentioning

confidence: 99%

Section: Superlubricity Of Mos 2 and Dlcmentioning

confidence: 99%

Section: Survey On Extremely Low Friction Under Boundary Lubricationmentioning

confidence: 99%

See 3 more Smart Citations

Superlubricity mechanism of diamond-like carbon with glycerol. Coupling of experimental and simulation studies

Bouchet

Matta

Le-Mogne

et al. 2007

J. Phys.: Conf. Ser.

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Accurate Simulation for 2D Lubricating Materials in Realistic Environments: From Classical to Quantum Mechanical Methods

Hao,

Sun,

et al. 2024

Advanced Materials

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Abstract2D materials such as graphene, MoS2, and hexagonal BN are the most advanced solid lubricating materials with superior friction and anti‐wear performance. However, as a typical surface phenomenon, the lubricating properties of 2D materials are largely dependent on the surrounding environment, such as temperature, stress, humidity, oxygen, and other environmental substances. Given the technical challenges in experiment for real‐time and in situ detection of microscopic environment–material interaction, recent years have witnessed the acceleration of computational research on the lubrication behavior of 2D materials in realistic environments. This study reviews the up‐to‐date computational studies for the effect of environmental factors on the lubrication performance of 2D materials, summarizes the theoretical methods in lubrication from classical to quantum‐mechanics ones, and emphasizes the importance of quantum method in revealing the lubrication mechanism at atomic and electronic level. An effective simulation method based on ab initio molecular dynamics is also proposed to try to provide more ways to accurately reveal the friction mechanisms and reliably guide the lubricating material design. On the basis of current development, future prospects, and challenges for the simulation and modeling in lubrication with realistic environment are outlined.

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Microtribology, squeeze, and friction of the colloidal layer

Mazuyer¹,

Tonck²,

Georges³

et al. 1995

Lubrication Science

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Lubricant films containing colloidal overbased calcium salts have particular effects on detergency and on the wear process. The mechanical properties of such boundary films are very dependent on the process conditions, and are essentially a result of physico‐chemical transformations of the colloid. Three types of films were compared: a film obtained by the drying of the base solvent, a film due to the compaction of the colloid between two steel surfaces, and a friction film obtained with this type of lubricant. Adsorption, compaction, and shear transformations induce a solid film. The pressure effect on the frictional behaviour of these colloidal films has been investigated using a surface force apparatus for low contact pressure (104 to 106 Pa), and using tribometers supporting heavy loads for the analysis of the high pressure domain. Above a critical pressure, evaluated at 106 Pa, the colloidal film does not flow, but forms a compacted mattress sliding on the surface plane and squeezing a molecular layer of lubricant.

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Hertzian stress contribution to low friction behavior of thin MoS2 coatings

Cited by 233 publications

References 18 publications

Superlubricity mechanism of diamond-like carbon with glycerol. Coupling of experimental and simulation studies

Superlubricity mechanism of diamond-like carbon with glycerol. Coupling of experimental and simulation studies

Accurate Simulation for 2D Lubricating Materials in Realistic Environments: From Classical to Quantum Mechanical Methods

Microtribology, squeeze, and friction of the colloidal layer

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