Carbon nanotubes as lubricant additives

The tribological performances of Ni/Y-based SWNT, Fe-based multi-wall carbon nanotubes (MWNT), and metal-free MWNT were compared. The addition of the three kinds of carbon nanotubes led to a reduction of friction. This reduction is more significant in the case of Ni/Y-based SWNT. The presence of many flake-like wear debris was observed in the two tests. In the case of Ni/Y-based nanotubes, these carpets were made of an amorphous carbon-based matrix containing Ni-rich catalyst nanoparticles. The presence of catalyst particles in these flake-like particles allowed to figure out the formation of a kind of Ni-doped DLC-like material. However, no iron was present in the particle material, in agreement with the good antiwear protection for the steel surface. In the case of metal-free MWNT, wear debris were composed of iron oxides and little carbon. This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).