Friction Dynamics of Confined Weakly Adhering Boundary Layers

Mazuyer, Denis; Cayer-Barrioz, Juliette; Tonck, A.; Jarnias, Frédéric

doi:10.1021/la703152q

Cited by 35 publications

(38 citation statements)

References 56 publications

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“…SFA has confirmed that saturated alkyl chain OFMs adsorb from solution to form vertically oriented monolayers on mica [59,61] and also cobalt surfaces [58,60] while QCM has shown that oleic acid molecules appear to adsorb parallel to the surface on iron [66]. In AFM/LFM a sphere or sharp tip is rubbed against a substrate to provide a reasonably close analogue of a high pressure sliding asperity contact.…”

Section: Ofm Research 1990s To Presentmentioning

confidence: 99%

“…These include the surface forces apparatus (SFA) [58][59][60][61], atomic/lateral force microscope (AFM/LFM) [62][63][64][65], quartz crystal microbalance (QCM) [66], ultrathin film interferometry (UTFI) [67], neutron reflectometry [68,69] and various surface-specific vibrational spectroscopies [70][71][72]. Methods were also developed to generate model close-packed monolayers by chemical grafting of self-assembled alkylthiols and alkyl siloxanes on solid surfaces [73][74].…”

Section: Ofm Research 1990s To Presentmentioning

confidence: 99%

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Friction Modifier Additives

2015

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The need for energy efficiency is leading to the growing use of additives that reduce friction in thin film boundary and mixed lubrication conditions. Several classes of such friction modifier additive exist, the main ones being organic friction modifiers, functionalised polymers, soluble organo-molybdenum additives and dispersed nanoparticles. All work in different ways. This paper reviews these four main types of lubricant friction modifier additive and outlines their history, research and the mechanisms by which they are currently believed to function. Aspects of their behaviour that are still not yet fully understood are highlighted.

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Section: Ofm Research 1990s To Presentmentioning

confidence: 99%

Section: Ofm Research 1990s To Presentmentioning

confidence: 99%

Friction Modifier Additives

2015

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“…Eventually, at very high speeds Drummond et al suggested that all nano-junctions were broken and friction originated from thin film viscous shear. Mazuyer et al have recently applied Drummond's model to the measured friction behaviour of solutions of two organic friction modifiers in polyalphaolefin base fluid in a surface forces apparatus [89].…”

Section: Boundary Frictionmentioning

confidence: 99%

Stress-augmented thermal activation: Tribology feels the force

2018

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Abstract:In stress-augmented thermal activation, the activation energy barrier that controls the rate of atomic and molecular processes is reduced by the application of stress, with the result that the rate of these processes increases exponentially with applied stress. This concept has particular relevance to Tribology, and since its development in the early twentieth century, it has been applied to develop important models of plastic flow, sliding friction, rheology, wear, and tribochemistry. This paper reviews the development of stress-augmented thermal activation and its application to all of these areas of Tribology. The strengths and limitations of the approach are then discussed and future directions considered. From the scientific point of view, the concept of stress-augmented thermal activation is important since it enables the development of models that describe macroscale tribological performance, such as friction coefficient or tribofilm formation, in terms of the structure and behaviour of individual atoms and molecules. This both helps us understand these processes at a fundamental level and also provides tools for the informed design of lubricants and surfaces.

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“…In addition to Schallamach's (and Eyring and Prandtl's) principle, that applied force reduces the energy barrier, thus allowing more rapid junction breaking, Drummond et al also assumed that all junctions will break when they reached a critical elastic deformation. Mazuyer et al have recently applied Drummond's model to the measured friction behaviour of solutions of two organic friction modifiers in polyalphaolefin base fluid in a surface force apparatus [25].…”

Section: Schallamach Modelmentioning

confidence: 99%

On the Commonality Between Theoretical Models for Fluid and Solid Friction, Wear and Tribochemistry

2015

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Tribology is concerned with the influence of mechanically applied forces on interfacial phenomena that accompany and control sliding. A wide range of models has been developed to describe these phenomena, which include frictional dissipation, wear and tribochemical reactions. This paper shows that these apparently disparate models are based on the same fundamental concept that an externally applied force accelerates the rate of thermal transition of atoms or molecules across energy barriers present in solid and liquid materials, thereby promoting flow, slip or bond cleavage. Such ''stress-assisted'' effects and the associated thermal activation concepts were developed independently and in different forms by Prandtl (Z Angew Math Mech 8:85, 1928) and Eyring (J Chem Phys 4(4): [283][284][285][286][287][288][289][290][291] 1936). These two works have underpinned subsequent theories of dry friction, boundary lubrication, EHD rheology, tribochemistry and nanoscale wear modelling. This paper first reviews the historical development of the concepts, focussing in particular on the models of Prandtl and Eyring and how they have subsequently been used and adapted by others. The two approaches are then compared and contrasted, noting that although superficially similar, they contain quite different assumptions and constraints. First, the Prandtl model assumes that the force is exerted through a compliant spring, while constant force sliding is assumed by Eyring. Second, different approximations are made in the two models to describe the change in energy barrier with external force. Prandtl explores the asymptotic behaviour of the energy barrier as the applied force become sufficiently high to reduce it to zero, while Eyring assumes that the energy barrier is reduced by an amount equal to the external work carried out on the system. The theoretical underpinnings of these differences are discussed along with the implications of compliant coupling and constant force sliding on the velocity and temperature dependence of the friction forces for the two models.

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Friction Dynamics of Confined Weakly Adhering Boundary Layers

Cited by 35 publications

References 56 publications

Friction Modifier Additives

Friction Modifier Additives

Stress-augmented thermal activation: Tribology feels the force

On the Commonality Between Theoretical Models for Fluid and Solid Friction, Wear and Tribochemistry

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