Energy filtering transmission electron microscopy and atomistic simulations of tribo-induced hybridization change of nanocrystalline diamond coating

Matta, C.; Vacher, Béatrice; Le-Mogne, T.; Martin, Jean Michel; Lautz, Julian von; Ma, Tianbao; Pastewka, Lars; Otschik, J.; Gumbsch, Peter; Moseler, Michael

doi:10.1016/j.carbon.2015.02.041

Cited by 69 publications

(49 citation statements)

References 48 publications

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“…This hybridization change has already been observed in the past with ta-C and nanocrystalline diamond lubricated by glycerol that gives a similar behaviour as oleic acid4447. For example, Fig.…”

Section: Discussionsupporting

confidence: 77%

“…This layer is not present in the pristine ta-C, which contains only approximately 30% of sp 2 carbon, and it is formed during the running-in period. The mechanism of the friction-induced change of carbon hybridization from sp 3 to sp 2 -carbon has also been studied by computer simulations47.When the sp 2 content reaches a certain threshold, a graphene-like planar structure spontaneously forms on the a-C surface, and the smoother surface finishing that is obtained decreases the local pressure and may allow oleic acid molecules to reach the contact zone. The role of the double bond present in oleic acid is still unclear but may participate to the aromatization of the top surface.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Diamond-like carbon coating under oleic acid lubrication: Evidence for graphene oxide formation in superlow friction

Bouchet

Martin

Ávila

et al. 2017

Sci Rep

102

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The achievement of the superlubricity regime, with a friction coefficient below 0.01, is the Holy Grail of many tribological applications, with the potential to have a remarkable impact on economic and environmental issues. Based on a combined high-resolution photoemission and soft X-ray absorption study, we report that superlubricity can be realized for engineering applications in bearing steel coated with ultra-smooth tetrahedral amorphous carbon (ta-C) under oleic acid lubrication. The results show that tribochemical reactions promoted by the oil lubrication generate strong structural changes in the carbon hybridization of the ta-C hydrogen-free carbon, with initially high sp3 content. Interestingly, the macroscopic superlow friction regime of moving mechanical assemblies coated with ta-C can be attributed to a few partially oxidized graphene-like sheets, with a thickness of not more than 1 nm, formed at the surface inside the wear scar. The sp2 planar carbon and oxygen-derived species are the hallmark of these mesoscopic surface structures created on top of colliding asperities as a result of the tribochemical reactions induced by the oleic acid lubrication. Atomistic simulations elucidate the tribo-formation of such graphene-like structures, providing the link between the overall atomistic mechanism and the macroscopic experimental observations of green superlubricity in the investigated ta-C/oleic acid tribological systems.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Diamond-like carbon coating under oleic acid lubrication: Evidence for graphene oxide formation in superlow friction

Bouchet

Martin

Ávila

et al. 2017

Sci Rep

102

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“…In self-mated a-C:H surfaces, hydrogen atoms in the bulk continuously saturate the chemically active dangling bonds, leading to much smoother interfacial behavior. Recently, it was found that a tribologically-induced hybridization change from sp 3 to sp 2 can take place on nanocrystalline diamond coatings even under mild tribological conditions [63]. In that study, repeated collisions between diamond asperities led to the formation of a soft sp 2 +sp amorphous C with interspersed nanodiamond grits (sp 3 ), where grits with {1 0 0} surfaces were particularly prone to decay under shear.…”

Section: Reactions Between Solid Surfacesmentioning

confidence: 98%

Tribochemistry: A Review of Reactive Molecular Dynamics Simulations

2020

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Tribochemistry, the study of chemical reactions in tribological interfaces, plays a critical role in determining friction and wear behavior. One method researchers have used to explore tribochemistry is “reactive” molecular dynamics simulation based on empirical models that capture the formation and breaking of chemical bonds. This review summarizes studies that have been performed using reactive molecular dynamics simulations of chemical reactions in sliding contacts. Topics include shear-driven reactions between and within solid surfaces, between solid surfaces and lubricating fluids, and within lubricating fluids. The review concludes with a perspective on the contributions of reactive molecular dynamics simulations to the current understanding of tribochemistry, as well as opportunities for this approach going forward.

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“…1(a) left], by formulating a critical length scale in terms of a competition between plastic deformation of an asperity under load and its breaking off [16]. In addition to predicting a minimum size of wear particles, it also provides a way to understand surface roughness evolution [17]: Purely plastic deformation of asperities has been found to mostly flatten the surfaces or lead to welding [18][19][20][21][22][23][24], while the breaking off of wear particles seems to be the ingredient to reroughen worked surfaces [17], although surface kinks due to dislocation plasticity have also been suggested as sources of roughness [25]. The critical length scale is most generally defined as…”

Section: Introductionmentioning

confidence: 99%

Adhesive wear mechanisms in the presence of weak interfaces: Insights from an amorphous model system

Brink

Molinari

2019

Phys. Rev. Materials

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Engineering wear models are generally empirical and lack connections to the physical processes of debris generation at the nanoscale to microscale. Here, we thus analyze wear particle formation for sliding interfaces in dry contact with full and reduced adhesion. Depending on the material and interface properties and the local slopes of the surfaces, we find that colliding surface asperities can either deform plastically, form wear particles, or slip along the contact junction surface without significant damage. We propose a mechanism map as a function of material properties and local geometry, and confirm it using quasi-two-dimensional and three-dimensional molecular dynamics and finite-element simulations on an amorphous, siliconlike model material. The framework developed in the present paper conceptually ties the regimes of weak and strong interfacial adhesion together and can explain that even unlubricated sliding contacts do not necessarily lead to catastrophic wear rates. A salient result of the present paper is an analytical expression of a critical length scale, which incorporates interface properties and roughness parameters. Therefore, our findings provide a theoretical framework and a quantitative map to predict deformation mechanisms at individual contacts. In particular, contact junctions of sizes above the critical length scale contribute to the debris formation.

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Energy filtering transmission electron microscopy and atomistic simulations of tribo-induced hybridization change of nanocrystalline diamond coating

Cited by 69 publications

References 48 publications

Diamond-like carbon coating under oleic acid lubrication: Evidence for graphene oxide formation in superlow friction

Diamond-like carbon coating under oleic acid lubrication: Evidence for graphene oxide formation in superlow friction

Tribochemistry: A Review of Reactive Molecular Dynamics Simulations

Adhesive wear mechanisms in the presence of weak interfaces: Insights from an amorphous model system

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