Macroscopic Superlow Friction of Steel and Diamond-Like Carbon Lubricated with a Formanisotropic 1,3-Diketone

Abstract

Energy dissipation due to friction and wear is reducing the energy efficiency and reliability of mechanical systems. Thus, great efforts are being made to minimize friction for technical applications. In our present work, we investigate the tribological behavior of stainless steel 100Cr6 with a-C:H and a-C:H:Si coating lubricated with a surface-active formanisotropic 1,3-diketone. The results show that superlow friction can be achieved on the macroscale using a steel 100Cr6 self pairing (COF ∼ 0.005) and with 100Cr6 in combination with a-C:H coating (COF ∼ 0.008). Furthermore, the replacement of steel with a-C:H coating leads to a considerable decrease of wear. The reduced COF arises from the chemical interaction of the lubricant with the surface and nascent iron ions. It was found that interfacial parameters correlate with tribological results. In addition, the alignment of the formanisotropic molecules in the tribological contact at thin-film lubrication leads to an anisotropic viscosity with a minimum shear resistance in sliding direction. Atomistic simulation of tribochemical interactions was conducted to derive a friction model based on the thin-film lubrication theory. This investigation indicates the potential to substantially reduce friction and wear using this fluid in real technical applications.

Towards programmable friction: control of lubrication with ionic liquid mixtures by automated electrical regulation

“…The applied bias voltage on the substrates also leads to a change in surface energy. Since the surface energy of the substrate and the surface tension of the lubricant influence the adhesion of the ions and thus the lubricating properties, the interfacial parameters of the system must be taken into account 35 – 37 . [P66614][BTA] (γ: 27.4 mN/m, 0.59 ratio polar/dispersive) has nearly the same surface tension but higher polarity than [P66614][DEHP] (γ: 30.5 mN/m, 0.19 ratio polar/dispersive).…”

Entwicklung von galvanisch gekoppelten Gleitlagern zur Reduzierung von Reibung und Verschleiß

“…In diesem Kontext werden unterschiedliche neuartige Additive wie ionische Flüssigkeiten (ILs: ionic liquids), mesogene Fluide (MF: mesogenic fluids) und ionische Flüssigkristalle (ILCs: ionic liquid crystals) diskutiert [4]. Eigene Vorarbeiten haben gezeigt, dass mit speziellen MFs tribologische Eigenschaften verbessert werden können, bis hin zu Realisierung ultraniedriger Reibung auf Stahl (µ < 0,005) [5][6][7] und auf diamantähnlichen Kohlenstoffschichten (diamond like carbon, DLC) [8]. ILs sind vielversprechende Additive, die aufgrund des ionischen Aufbaus starke Wechselwirkung mit Oberflächen zeigen.…”

Investigation of ionic liquids with and without graphene as lubricant additive for metal/metal and metal/PEEK contacts over a wide temperature range

“…Research to improve tribological behaviour currently aims in several directions. 4 Superlubricity [5][6][7][8][9] to improve energy efficiency, bio-based lubricants 10 and ionic liquids (ILs) as environmentally friendly lubricants derived from renewable biomaterials, 11 diamond like carbon coatings, 12 graphene 13 and recently carbon quantum dots as lubricant additives [14][15][16][17] are among others part of research to improve the sustainability of tribological systems. 18,19 Specialists in the field of environmentally friendly lubricants discuss currently about lubricants, water-based lubricants containing graphene and onion-like carbon, 20 liquid crystals (LCs), 21 ILs [22][23][24][25] and ionic liquid crystals (ILCs).…”