Nanoparticles as novel lubricating additives in a green, physically based lubrication technology for DLC coatings

• Published in: Wear Vol. 303; no. 1-2; pp. 480 - 485
• Main Authors: Kalin, M., Kogovšek, J., Remškar, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-06-2013; Elsevier
• Subjects: Additives; Ashes; Coatings; Cross-disciplinary physics: materials science; rheology; Diamond-like carbon films; DLC coatings; Exact sciences and technology; Friction; Friction, lubrication, and wear; Lubricant additives; Lubrication; Materials science; Molybdenum disulfide; MoS2 nanotubes; Nanoparticles; Physical-based lubrication; Physics; Product innovation; Solid lubricants; Treatment of materials and its effects on microstructure and properties; Wear; Nanoparticles; DLC coatings; Physical-based lubrication; Solid lubricants; Lubricant additives; MoS2 nanotubes; Tungsten sulfide; Additives; Molybdenum sulfide; Diamond-like carbon; Surface analysis; MoS; nanotubes; Friction; Wear; Lubricating oils; Lubrication; Steels; Performance; Chemical reactivity; Ball on disk testing
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2013.03.009

Diamond-like carbon (DLC) coatings provide low friction and wear in the most demanding tribological contacts. However, their chemical reactivity with oil additives is poor and difficult to optimise. Moreover, even the partially effective, but high-SAPS (sulphuric ash, phosphor, sulphur) additives, will be phased out in the near future for environmental reasons. Based on recent advancements in the nanotechnology of inorganic MoS2 and WS2 nanoparticles, which lubricate through the low shear of basal planes, we propose a potential replacement of the current chemical-based lubrication with this novel, physical-based additive lubrication technology for poorly reactive DLC coatings. In our work, 30% less friction compared to steel surfaces and 50% less friction compared to the base oil was achieved by employing MoS2 nanotubes in the base oil in self-mated DLC contacts. This physical-based lubrication technology represents an innovative solution for highly effective but non-reactive surfaces and simultaneously provides green-lubrication performance.
•Study of DLC and steel lubricated with MoS2 nanotubes in all lubrication regimes.•Physically based lubrication has environmental benefits vs. chemically-based.•Proof of successful physically based lubrication of DLC with nanoparticles is given.•Tribofilm that reduces friction in DLC contacts can be thick or ultra-thin.•Friction reduction of DLC contacts (50%) is even larger than in steel contacts (40%).