Ultra-low friction

For a-C H coating, the friction coefficient is strongly influenced by H content in the coating, and by relative humidity (RH). At low humidity, the friction coefficient can be achieved as low as 0.02 [25]. The friction coefficient increases to 0.1 0.15 as the RH rises to 30 % and above. An ultra-low friction coefficient of 0.001 0.005 was reported to be achieved for high hydrogen content a-C H coating in... 

Based on the discussion in earlier sections of this chapter, one may expect atomically flat incommensurate surfaces to be superlubric. Indeed the first suggestion that ultra-low friction may be possible was based on simulations of copper surfaces.6,7 Furthermore, the simulations of Ni(100)/(100) interfaces discussed in the previous section showed very low friction when the surfaces were atomically flat and misoriented (see the data for the atomically flat system between 30° and 60° in Figure 21). In general, however, it is reasonable to assume that bare metals are not good candidates for superlubric materials because they are vulnerable to a variety of energy dissipation mechanisms such as dislocation formation, plastic deformation, and wear. 

Aparin, V.l. and Dukhovskoi, E.A., Significant Enhancement of Orientation of Molybdenum Disulfide Surface Layer from Irradiation Resulting in Ultra-Low Friction when Paired with a Metal, DAN SSSR, 217, 599, (1974). 

Kaneko D, Tada T, Kurokawa T, Gong JP, Osada Y (2004) Mechanically strong hydrogels with an ultra low friction coefficient. Adv Mater 17 535-538... 

Some very recent stodies on protic ammonium species solely composed of C, O, N and H are very promising in preventing wear and giving ultra-low friction even in water [42,65,66], although the thermal stability of these species is not so high as that of the halogen-containing imidazolium salts. 

Espinosa T, Jimenez M, Sanes J, Jimenez A-E, Iglesias M, Bermudez M-D (2014) Ultra-low friction with a protic ionic liquid boundary film at the water-lubricated sapphire-stainless steel interface. Tribol Lett 53(1) 1-9. doi 10.1007/sl 1249-013-0238-3... 

F. Hollman, Micro- and Nanocrystalline Diamond Coatings with Extreme Wear Resistance and Ultra Low Friction, Dissertation, Uppsala University, 1997 ). Lovelock, Gaia a new look at life on Earth, 1982 and The ages of Gaia, 1988. Oxford University Press D. V. Hoyt, K. H. Schatten, The Role of the Sun in Climate Change, Oxford University Press, 1997... 

Souza JCM, Henriques M, Oliveira R, et al Biofilms inducing ultra-low friction on titanium, JDenr Res 89 1470-1475, 2010. 

Luedtke and Landman observed that at velocities even higher than Vc, eventually a state of ultralow kinetic friction occurs. Landman et al. observed this ultra-low friction regime also by lateral sinusoidal perturbation with small amplitudes ( 1 A)... 

Chhowalla, M. and Amaratunga, G. A. J., Thin films of fullerene-like M0S2 nanoparticles with ultra-low friction and wear. Nature, 407, 2000,164-167. 

Cizaire, L., Vacher, B., Le-Mogne, T, Martin, J. M., Rapoport, L., Margolin, A. and Terme, R., Mechanisms of ultra-low friction by hollow inorganic fullerene-like M0S2 nanopaiticles. Surface and Coatings Technology, 160,2002,282-287. 

Joly-Pottrrz, L., Dassenoy, F., Belin, M., Vacher, B., Martin, J. M. and Fleischer, N., Ultra-low friction and wear properties of IF-WS2 under boundary lubrication. Tribology letters, 18 (4), 2005, 477-485. 

Hiratsuka, K., Bohno, A. and Kurosawa, M., (2000), Ultra-low friction between water droplet and hydrophobic surface. Proc. NATO Course, Keszthely, Hungary, August 2000, Fundamentals of Tribology and Bridging the Gap between Macro- and Micro/Nanoscales., pp. 345-348, ed. B Bhushan, publ. Kluwer Acad. Publ. Netherlands. 

Except for the anomalous low friction reported for an ultra-pure sputtered film (see Section 10.5) and under radiation (see Section 7.4), typical minimum coefficients of friction in dry air or vacuum are 0.02 to 0.03. For fully disordered films in dry air the static coefficient of friction can be between 0.12 and 0.15, but because reorientation begins rapidly when movement starts any figures for the kinetic friction of disordered films must be suspect. 

Ram Ramirez, M. X., Walters, K. B., Hirt, D. E. Relationship between erucamide surface concentration and coefficient of friction of LLDPE film. J. Vinyl Additive Technol. 11 (2005) 9-12. 06Bur Burris, D. L., Sawyer, W. G. A low friction and ultra low wear rate PEEK/PTFE composite. Wear 261 (2006) 410 18. 

Burris DL, Sawyer WG. A low friction and ultra low wear rate PEEK/PTFE composite. Wear 2006 261(3 ) 410-8. 

Polymeric ultra-fine particle-adsorbed structures with antistatic, low-friction, and abrasion-resistant properties were prepared by Akaishi, et al. [54]. The structures comprise various substrates laminated with charged polymeric thin films on which charged polymer ultra-fine particles, prepared by a macromon-... 

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