Fullerence particles as an additive to liquid lubricants and greases for low friction and wear

Abstract

Fullerene (C{sub 60}-rich) powder is tested as an additive to liquid lubricants and greases to improve their friction and wear characteristics. The coefficient of friction and wear of a 52100 steel ball sliding against a hardened M50 steel disk are measured at the contact in the presence of base petroleum oil with and without fullerene particles. For comparison, tests are also conducted in the presence of base oil with graphite and MoS{sub 2} powders (5 wt%). It was found that a 5 wt% addition of fullerene to base oil resulted in a reduction in width of the wear scar on the steel disk from 300-380 {mu}m to 120-130 {mu}m, and the diameter of the wear scar on the mating steel ball was reduced from approximately 200 {mu}m to 60 {mu}m. The coefficient of friction in the presence of oil with 5 wt% fullerene is observed to be approximately 20 percent lower than that of base oil with no additives. The improvements in friction and wear for fullerenes are comparable to those for graphite and MoS{sub 2} additives. Limited experiments conducted on diester grease with fullerene and solid lubricants demonstrate similar trends. The improvements in friction and wear are likely duemore » to the formation of a transfer film at the contact region and the presence of C{sub 60} clusters which may act as tiny ball bearings which facilitate sliding. 19 refs., 4 figs., 3 tabs.« less