FULLERENE (C-60) FILMS FOR SOLID LUBRICATION

The advent of techniques for producing gram quantities of a new form o f stable, pure, solid carbon, designated as fullerene, opens a profusi on of possibilities to be explored in many disciplines including tribo logy. Fullerenes take the form of hollow, geodesic domes, which are fo rmed from a network of pentagons and hexagons with covalently bonded c arbon atoms. The C60 molecule has the highest possible symmetry (icosa hedral) and assumes the shape of a soccer ball. At room temperature, f ullerene molecules pack in a face centered cubic (fcc) lattice bonded with weak van der Waals attractions. Fullerenes can be dissolved in so lvents such as toluene and benzene and are easily sublimed. The low su rface energy, high chemical stability, spherical shape, weak intermole cular bonding, and high load bearing capacity Of C60 molecules offer p otential for various mechanical and tribological applications. This pa per describes the crystal structure and properties of fullerenes and p roposes a mechanism for self-lubricating action. Sublimed films of C60 have been produced and friction and wear performance of these films i n various operating environments are the subject of this paper. The re sults of this study indicate that C60, owing to its unique crystal str ucture and bonding, may be a promising solid lubricant.