Atmospheric effects on the adhesion and friction between non-hydrogenated diamond-like carbon (DLC) coating and aluminum – A first principles investigation

Qi, Yue; Konca, Erkan; Alpas, A.T.

doi:10.1016/j.susc.2006.05.008

Cited by 156 publications

(104 citation statements)

References 53 publications

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“…Specifically, Dag and Ciraci demonstrated the existence of strong repulsive forces between hydrogen-terminated diamond (001) surfaces using ab initio method, especially when the distance between such surfaces is brought down to less than 2.5 Å [28]. In a similar study based on density functional theory, Qi et al examined the H-terminated diamond (111) surfaces approaching each other [29]. They also found that the system energy changes considerably as the interfacial distance becomes increasingly small.…”

Section: Resultsmentioning

confidence: 99%

Investigation of Initial and Steady-State Sliding Behavior of a Nearly Frictionless Carbon Film by Imaging 2- and 3-D TOF-SIMS

Eryilmaz

Erdemir

2007

Tribol Lett

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Using imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS), we investigated the initial and steady-state sliding behavior of a nearly frictionless carbon (NFC) film. Specifically, TOF-SIMS images (both 2-D and 3-D) of these surfaces were constructed to highlight the spatial distributions of ionized and molecular species that were present on as-received and friction-tested NFC surfaces and as a function of depth. As a complementary technique, we used X-ray photoelectron spectroscopy (XPS) to gain further insight into the chemical nature of the sliding surfaces. The NFC films were produced on Si wafers and steel substrates in a gas discharge plasma that consisted of 25 vol.% methane and 75 vol.% hydrogen using a plasmaenhanced chemical vapor deposition (PECVD) system. They were then subjected to sliding friction and wear experiments in a pin-on-disk machine under 5-and 10-N loads and at sliding velocities of 0.2-0.5 m/s in dry nitrogen. The initial friction coefficients of the NFC films were in the range of 0.05-0.1, but decreased rapidly to values less than 0.01 at steady state. Positive and negative TOF-SIMS spectra and 2-and 3-D images reconstructed from selected masses revealed that the elemental distribution of certain chemical species differs substantially between undisturbed and tribo-tested areas of the NFC films. Specifically, the tribo-tested areas are essentially made up of carbon and hydrogen, while undisturbed or as-received areas are covered by a layer that is rich in oxygen and other species. These findings correlate well with the initial and steady-state friction coefficients of these films and help further explain their superlubricity in inert test environments.

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Section: Resultsmentioning

confidence: 99%

Investigation of Initial and Steady-State Sliding Behavior of a Nearly Frictionless Carbon Film by Imaging 2- and 3-D TOF-SIMS

Eryilmaz

Erdemir

2007

Tribol Lett

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“…They also show that as the concentration of H 2 O increases, the formation of a surface involving both hydride and hydroxyl terminations is favorable 54 . As well, DFT applied by Qi et al 56 showed that breaking one of the O-H bonds in water and then passivating two carbon atoms with the resultant H and OH groups has an adsorption energy of 1.8 eV/molecule. Overwhelmingly, the DFT work concludes that the dissociative adsorption of H 2 O to form C-H and C-OH groups on the surface is expected.…”

Section: G Theoretical Support For Passivation Mechanismmentioning

confidence: 98%

Influence of surface passivation on the friction and wear behavior of ultrananocrystalline diamond and tetrahedral amorphous carbon thin films

et al. 2012

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Highly sp3 -bonded, nearly hydrogen-free carbon-based materials can exhibit extremely low friction and wear in the absence of any liquid lubricant, but this physical behavior is limited by the vapor environment. The effect of water vapor on friction and wear are examined as a function of applied normal force for two such materials in thin film form -one that is fully amorphous in structure (tetrahedral amorphous carbon, or ta-C) and one that is polycrystalline with <10 nm grains (ultrananocrystalline diamond, or UNCD). Tribologically-induced changes in the chemistry and carbon bond hybridization at the surface are correlated with the effect of the sliding environment and loading conditions through ex-situ, spatially resolved near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. At sufficiently high relative humidity (RH) levels and/or sufficiently low loads, both films quickly achieve a low steady-state friction coefficient and subsequently exhibit low wear. For both films, the number of cycles necessary to reach the steady-state is progressively reduced for increasing RH levels. Worn regions formed at lower RH and higher loads have a higher concentration of chemisorbed oxygen than those formed at higher RH, with the oxygen singly-bonded as hydroxyl groups (C-OH). While some carbon rehybridization from sp 3 to disordered sp 2 bonding is observed, no crystalline graphite formation is observed for either film. Rather, the primary solid-lubrication mechanism is the 2 passivation of dangling bonds by OH and H from the dissociation of vapor-phase H 2 O. This vapor-phase lubrication mechanism is highly effective, producing friction coefficients as low as 0.078 for ta-C and 0.008 for UNCD, and wear rates requiring thousands of sliding passes to produce a few nanometers of wear.

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“…We do not claim that this corresponds to the instantaneous chemistry present during sliding, but rather that in the worn region: (a) ordered graphite is not formed since it would not disappear upon ambient exposure; and (b) oxidized species indicate that dangling bonds were produced and eventually passivated. Given the rapid dissociation times and highly favorable energetics of water dissociation on the diamond dangling bonds [32] passivation likely occurred during sliding. Chemical modifications can occur TABLE I.…”

mentioning

confidence: 99%

Origin of Ultralow Friction and Wear in Ultrananocrystalline Diamond

et al. 2008

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Atmospheric effects on the adhesion and friction between non-hydrogenated diamond-like carbon (DLC) coating and aluminum – A first principles investigation

Cited by 156 publications

References 53 publications

Investigation of Initial and Steady-State Sliding Behavior of a Nearly Frictionless Carbon Film by Imaging 2- and 3-D TOF-SIMS

Investigation of Initial and Steady-State Sliding Behavior of a Nearly Frictionless Carbon Film by Imaging 2- and 3-D TOF-SIMS

Influence of surface passivation on the friction and wear behavior of ultrananocrystalline diamond and tetrahedral amorphous carbon thin films

Origin of Ultralow Friction and Wear in Ultrananocrystalline Diamond

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