Wear, Plasticity, and Rehybridization in Tetrahedral Amorphous Carbon

Kunze, Tim; Posselt, M.; Gemming, Sibylle; Seifert, Gotthard; Konicek, Andrew R.; Carpick, Robert W.; Pastewka, Lars; Moseler, Michael

doi:10.1007/s11249-013-0250-7

Cited by 99 publications

(114 citation statements)

References 45 publications

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“…Percentile values P95 for the absolute DFT values are given; these measure the range of data the GAP has to "learn". 75 and to ta-C, 76 and are faster than GAP by about a factor of 50.…”

Section: Structural Propertiesmentioning

confidence: 94%

Machine learning based interatomic potential for amorphous carbon

2017

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We introduce a Gaussian approximation potential (GAP) for atomistic simulations of liquid and amorphous elemental carbon. Based on a machine-learning representation of the density-functional theory (DFT) potential-energy surface, such interatomic potentials enable materials simulations with close-to DFT accuracy but at much lower computational cost. We first determine the maximum accuracy that any finite-range potential can achieve in carbon structures; then, using a novel hierarchical set of two-, three-, and many-body structural descriptors, we construct a GAP model that can indeed reach the target accuracy. The potential yields accurate energetic and structural properties over a wide range of densities; it also correctly captures the structure of the liquid phases, at variance with state-of-the-art empirical potentials. Exemplary applications of the GAP model to surfaces of "diamond-like" tetrahedral amorphous carbon (ta-C) are presented, including an estimate of the amorphous material's surface energy, and simulations of high-temperature surface reconstructions ("graphitization"). The new interatomic potential appears to be promising for realistic and accurate simulations of nanoscale amorphous carbon structures.

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“…Percentile values P95 for the absolute DFT values are given; these measure the range of data the GAP has to "learn". 75 and to ta-C, 76 and are faster than GAP by about a factor of 50.…”

Section: Structural Propertiesmentioning

confidence: 94%

Machine learning based interatomic potential for amorphous carbon

2017

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“…Furthermore, the passivation of dangling bonds seems to play an important role [8]. The importance of the local sp3-sp2 transition and the corresponding formation of a soft amorphous layer were corroborated by a further study [9]. Furthermore, it was demonstrated that the polishing of a diamond crystal with a suspension of diamond particles depends on the formation of an amorphous layer and local sp3-sp2 transition [10].…”

Section: Introductionmentioning

confidence: 73%

“…Strong bonds between carbon atoms both within the amorphous layer and with the diamond substrate are causing high resistance forces, as shown by the red curves in Figure 11. According to Kunze et al [9], low friction of an amorphous carbon layer can only be expected if dangling bonds are passivated by ambient gases. Since such reactions were not considered in the present simulations, the friction forces remained high.…”

Section: Discussionmentioning

confidence: 99%

MD Sliding Simulations of Amorphous Tribofilms Consisting of either SiO2 or Carbon

2016

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Abstract:The sliding behaviors of two simplified tribofilms with amorphous structure consisting either of SiO 2 molecules or C atoms were simulated by molecular dynamics modeling. The objective was to identify mechanisms explaining the experimentally observed lubricating properties of the two amorphous films. The impacts of layer thickness, normal pressure, temperature and different substrate materials were studied systematically, while the sliding velocity was kept constant at 30 m/s. While the layer thickness was not critical, all the other parameters showed special effects under certain conditions. Normal pressure impeded void formation and could even eliminate voids if applied at high temperature. Stick-slip sliding was changed to smooth sliding at high temperature due to void healing. Considering the carbon film, high friction forces and shearing of the entire film was observed with diamond substrates, whereas interface sliding at low friction forces and an amorphous layer of iron mixed with carbon was observed if the supporting substrates consisted of α-Fe. Both films show a decrease of friction forces and smooth sliding behavior at elevated temperature, corresponding well to the tribological behavior of an advanced nanocomposite sliding against a steel disc under severe stressing conditions when high flash temperatures can be expected.

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“…This ultra-low friction is thought to be generated by forming very thin and weak tribofilm at the mixed lubrication condition. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Martin et al proposed the possible mechanism of the super low friction was the forming water layer by the tribochemical reaction between ta-C and glycerol. [28][29][30][31][32][33] In this paper, the formation of water and acid was indicated as one possible chemical reaction for glycerol, as shown in (a) (a) (b) (b) For the oleic acid test, the water can be supplied from the ambient air.…”

Section: Resultsmentioning

confidence: 99%

Low Friction Property of Diamond-Like Carbon Coating Films and Oxygen Transmission Ratio of Amorphous Carbon Films Deposited by Advanced Coating Processes

Watanabe¹,

Kano²,

Yoshida³

et al. 2012

Jpn. J. Appl. Phys.

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The topics of the applied technology of amorphous carbon film to reduce friction using diamond-like carbon (DLC) coated by the vacuum arc ion plating process and to improve the gas barrier property using the amorphous carbon film by the atmospheric pressure plasma process are introduced with the basic experimental results. For reducing friction, the super low friction coefficient below 0.01 has been found when the tetrahedral amorphous carbon coating deposited by T-shape filtered arc deposition method [ta-C(T)] was evaluated the friction property under oleic acid lubrication at pure sliding condition. It was thought that the low share strength tribofilm composed of water and oleic acid mono-layer seemed to be formed on the sliding interface. For gas barrier performance, the amorphous carbon film deposited by the atmospheric pressure plasma chemical vapour deposition (CVD) technique on poly(ethylene terephthalate) (PET) substrate was improved the oxygen transmission ratio (OTR) around 30% compared with that of uncoated PET substrate. These advanced performance obtained by the optimum material combination of DLC with lubricant and the original atmospheric pressure plasma CVD technique are expected to be applied on the actual application for the different types of the industrial fields in near future. #

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Wear, Plasticity, and Rehybridization in Tetrahedral Amorphous Carbon

Cited by 99 publications

References 45 publications

Machine learning based interatomic potential for amorphous carbon

Machine learning based interatomic potential for amorphous carbon

MD Sliding Simulations of Amorphous Tribofilms Consisting of either SiO2 or Carbon

Low Friction Property of Diamond-Like Carbon Coating Films and Oxygen Transmission Ratio of Amorphous Carbon Films Deposited by Advanced Coating Processes

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