Superlubricity and Wearless Sliding in Diamondlike Carbon Films

Erdemir, Ali

doi:10.1557/proc-697-p9.1

Cited by 13 publications

(21 citation statements)

References 32 publications

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“…Just like H-free a-C, they exhibit a decrease in friction coefficient in the presence of water vapor [176]. The main difference of UNCD and ta-C from H-DLC must come from the difference in the surface energy and reactivity of the surfaces of these materials [187]. On UNCD, Konicek et al found that, at low normal loads, an RH of as low as 0.5% was sufficient to eliminate the run-in period of high friction and gave ultra-low friction coefficient [188,189].…”

Section: Environmental Effect On Friction and Wear Of Carbon Materialsmentioning

confidence: 99%

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

et al. 2015

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Tribology involves not only two-body contacts of two solid materials-a substrate and a counter-surface; it often involves three-body contacts whether the third body is intentionally introduced or inevitably added during the sliding or rubbing. The intentionally added third body could be lubricant oil or engineered nanomaterial used to mitigate the friction and wear of the sliding contact. The inevitably added third body could be wear debris created from the substrate or the counter surface during sliding. Even in the absence of any solid third-body between the sliding surfaces, molecular adsorption of water or organic vapors from the surrounding environment can dramatically alter the friction and wear behavior of solid surfaces tested in the absence of lubricant oils. This review article covers the last case: the effects of molecular adsorption on sliding solid surfaces both inevitably occurring due to the ambient test and intentionally introduced as a solution for engineering problems. We will review how adsorbed molecules can change the course of wear and friction, as well as the mechanical and chemical behavior, of a wide range of materials under sliding conditions.

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Section: Environmental Effect On Friction and Wear Of Carbon Materialsmentioning

confidence: 99%

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

et al. 2015

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“…Within the range of these studies single crystal diamond surfaces have been extensively employed as models of the more important larger-scale industrial surfaces. Insight gained from these studies has helped the community understand surface energetic processes, including the recent manifestation of super lubricity of hydrogen-covered surfaces [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Fluorination of these surfaces has also been explored in an effort to further reduce the coefficient of friction (COF); in particular it was noted that the significant accumulated negative charge on the surface fluorine atom and its tight surface structure, due to strong lateral interactions, lead to a strong repulsive force between interacting surfaces (larger than when hydrogen terminated) [17]. This decrease in friction between interacting surfaces can have far ranging industrial and environmental importance [5,18,19].…”

Section: Introductionmentioning

confidence: 99%

Atomistic Frictional Properties of the C(100)2x1-H Surface

Jones

Tang

Hsia

et al. 2013

Advances in Tribology

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Density functional theory-(DFT-) based ab initio calculations were used to investigate the surface-to-surface interaction and frictional behavior of two hydrogenated C(100) dimer surfaces. A monolayer of hydrogen atoms was applied to the fully relaxed C(100)2x1 surface having rows of C=C dimers with a bond length of 1.39Å. The obtained C(100)2x1-H surfaces (C-H bond length 1.15Å) were placed in a large vacuum space and translated toward each other. A cohesive state at a surface separation of 4.32Å that is stabilized by approximately 0.42 eV was observed. An increase in the charge separation in the surface dimer was calculated at this separation having a 0.04 e transfer from the hydrogen atom to the carbon atom. The Mayer bond orders were calculated for the C-C and C-H bonds and were found to be 0.962 and 0.947, respectively. C-H bonds did not change substantially from the fully separated state. A significant decrease in the electron density difference between the hydrogen atoms on opposite surfaces was seen and assigned to the effects of Pauli repulsion. The surfaces were translated relative to each other in the (100) plane, and the friction force was obtained as a function of slab spacing, which yielded a 0.157 coefficient of friction.

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“…The friction coefficients of these films are low in humid test environments but become high in vacuum or inert test chambers. DLC films consisting of mostly sp 3 -bonded carbons are very hard (like diamond), and their tribological behavior is claimed to be similar to that of diamond [23,[39][40][41].…”

Section: Classification Of Dlc Filmsmentioning

confidence: 99%

“…In particular, the friction coefficients of highly hydrogenated (containing ~40 at. % hydrogen) DLCs were reported to be as low as 0.001 in dry nitrogen and/or high vacuum environments [23]. Such superlow friction values are not attainable with hydrogen-free DLC films.…”

Section: Chemical and Structural Nature Of Superlubricious Dlc Filmsmentioning

confidence: 99%

An Overview of Superlubricity in Diamond-like Carbon Films

Erdemir

Fontaine

Donnet

Tribology of Diamond-Like Carbon Films

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Diamond-like carbon (DLC) films have emerged as a class of very important tribological materials in recent years mainly because of their outstanding properties, such as high mechanical strength and hardness, excellent chemical inertness, and exceptional friction and wear performance under both dry and lubricated sliding conditions. Persistent and systematic research efforts during the last decade have resulted in the development of a new breed of DLC films providing superlubricity and near-wearless sliding even under very harsh contact and environmental conditions. In fact, the dry sliding friction and wear coefficients (i.e., as low as 0.001 and 10 −11 mm 3 /N.m, respectively) of these films are among the lowest reported to date, and such unusual tribological properties may have huge positive impacts on efficiency, durability, and performance characteristics of a wide range of mechanical systems, including magnetic hard disks, sliding and/or rolling contact bearings, gears, mechanical seals, scratch-resistant glasses, invasive and implantable medical devices, microelectromechanical systems (MEMS) and many more. In this chapter, we attempt to provide an up-to-date overview of these novel DLC films that can provide superlubricity and discuss in detail those factors that control their very unique lubrication mechanisms. Specifically, we concentrate on the state of the art in our understanding of their superlow friction and wear mechanisms, and how these mechanisms may relate to their structural chemistry, mechanical properties, and test and environmental conditions. In particular, various intrinsic (film-specific) and extrinsic (or test condition-specific) factors that play major roles in friction and wear of DLC films are discussed in detail and correlated with their friction and wear mechanisms.

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Superlubricity and Wearless Sliding in Diamondlike Carbon Films

Cited by 13 publications

References 32 publications

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

Atomistic Frictional Properties of the C(100)2x1-H Surface

An Overview of Superlubricity in Diamond-like Carbon Films

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