Topic
Friction modifier
About: Friction modifier is a research topic. Over the lifetime, 1576 publications have been published within this topic receiving 20258 citations.
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TL;DR: In this article, the authors reviewed the behavior of polymers from the mid-20th century to the present day and determined the surface energy of different coatings with new contact adhesion meter.
633 citations
TL;DR: In this paper, the fundamental mechanisms of solid lubrication are reviewed with examples from well-known solid lubricants like the transition metal dichalcogenides and diamond-like carbon families of coatings.
Abstract: The fundamental mechanisms of solid lubrication are reviewed with examples from well-known solid lubricants like the transition metal dichalcogenides and diamond-like carbon families of coatings. Solid lubricants are applied either as surface coatings or as fillers in self-lubricating composites. Tribological (friction and wear) contacts with solid lubricant coatings typically result in transfer of a thin layer of material from the surface of the coating to the counterface, commonly known as a transfer film or tribofilm. The wear surfaces can exhibit different chemistry, microstructure, and crystallographic texture from those of the bulk coating due to surface chemical reactions with the surrounding environment. As a result, solid lubricant coatings that give extremely low friction and long wear life in one environment can fail to do so in a different environment. Most solid lubricants exhibit non-Amontonian friction behavior with friction coefficients decreasing with increasing contact stress. The main mechanism responsible for low friction is typically governed by interfacial sliding between the worn coating and the transfer film. Strategies are discussed for the design of novel coating architectures to adapt to varying environments.
529 citations
TL;DR: In this article, the authors present a review of four main types of friction modifier additive and outline their history, research and the mechanisms by which they are currently believed to function, including organic friction modifiers, functionalised polymers, soluble organo-molybdenum additives and dispersed nanoparticles.
Abstract: 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.
374 citations
TL;DR: There are three types of friction modifiers for liquid lubricants: organomolybdenum compounds, organic friction modifiers, as well as nanoparticles as mentioned in this paper, and the problems and some suggestions for the future directions of research on friction modifiers are proposed.
Abstract: Due to the increasing demand of low emission and fuel economy, friction modifiers have been widely used in lubricating compositions to adjust friction and wear properties of lubricants. Recent achievements in the application of friction modifiers for liquid lubricants (2007–present) are reviewed in this paper. There are three types of friction modifiers for liquid lubricants: organomolybdenum compounds, organic friction modifiers, as well as nanoparticles. The tribological properties and lubrication mechanisms of these friction modifiers are discussed. The problems and some suggestions for the future directions of research on friction modifiers are proposed.
329 citations
TL;DR: In this article, a small amount of closed-cage structure (fullerene-like IF) was added to WS2 oil to reduce the friction coefficient and wear rate, and increase the loadbearing capacity of the friction pairs.
Abstract: WS2 nanoparticles with closed-cage structure (fullerene-like IF) are already being synthesized in macroscopic amounts from the respective oxide nanoparticles. They have been studied as superior solid lubricants under harsh conditions in recent years. Under severe contact conditions both fluids and greases are squeezed out from the contact area and consequently do not provide adequate lubrication conditions. Addition of even a small amount of IF nanoparticles to the oil was found to reduce the friction coefficient and wear rate, and increase the load-bearing capacity of the friction pairs. Furthermore, IF nanoparticles were impregnated into polymer and metal coatings and into self-lubricating porous metal parts, and were found to alleviate both friction and wear remarkably well. In another set of experiments, IF nanoparticles were shown to provide excellent tribological behavior for the contact between a ceramic alumina block and silicon nitride ball.The mechanism for the impro ved tribological behavior of the IF nanoparticles is being investigated. In addition to the rolling friction, gradual exfoliation of the IF onions and transfer of monomolecular WS2 sheets onto the metal surface (third body transfer) is shown to play a major role in alleviating friction and wear. This work suggests numerous applications for this new solid-state nanolubricant.
216 citations