Carbon-Based Nanolubricants

Nanolubricants Edited by J. M. Martin and N. Ohmae 2008 John Wiley Sons, Ltd. ISBN 978-0-470-06552-5 

Recently, a new synthesis method based on the decomposition of CH4 on NiO/Al composite powder led to a massive production of carbon onions of about Ig per hour [27, 28]. These carbon onions have a diameter from 5 to 50 nm but some carbon onions contain an Ni core. Wang et al. developed a synthesis method of carbon onions containing Fe core by CVD [29]. C2H2 is decomposed on ferrocene and leads to the formation of carbon onions 15 to 40 nm in diameter. The presence of a metallic core (Fe or Ni) can affect the tribological properties of carbon onions, as previously demonstrated in the case of carbon nanotubes. Carbon onions containing an Ni core would present interesting tribological properties similar to those of carbon nanotnbes (see Section 3.5.1.1). 

So far, very few stndies on the tribological properties of carbon onions are reported in the literature. Most of the smdies were carried out on carbon onions concern their synthesis and the determination of their structures. Cabioc h et al. smdied the tribological properties of silver films containing carbon onions [30]. The addition of onions does not have an effect on the friction coefficient, but an increase in lifetime of the coating by a factor of 15 was observed. Cabioc h et al. explained friction-reducing properties of carbon onions by the fact that they are embedded inside the metal, so they cannot roll. Hirata et al. smdied tribological 

The low-loss peak corresponds to the excitation of valence electrons n + cr). Recent studies showed that the plasmon peak is of particular interest in the study of mechanical and physical properties of materials [33]. A correlation between the plasmon maximum energy 

Multiwavelength Raman spectroscopy is currently used to study carbon compounds. There is a large diversity of carbon compounds depending on the ratio of sp to sp that can be 

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