The antifriction behaviours of C-60/C-70

In this paper, the antifriction behaviours of C-60/C-70 (3:1) molecules and their crystal powder were evaluated by different methods. It was found that the C-60/C-70 crystal powder possessed hexagonal close packed (hcp) crystal structure with a = 10.1 Angstrom and c = 16.55 Angstrom, and a transformation of crystal structure from hcp to face centred cubic (fee) occurred easily during friction (burnishing). It was confirmed that two kinds of process, breakage of C-60/C-70 powder coagulated by nanoscale single crystals and rearrangement of the molecules along the friction direction, had occurred under the friction force. The extreme pressure (EP) performance of C-60/C-70 as an additive in paraffin liquid was investigated on an SRV oscillating wear machine. It was found that the extreme pressure load (EP value) of paraffin liquid was increased by dispersion of C-60/C-70 powder, accompanied by a slight improvement in the antifriction behaviour. it was confirmed that the improvement in EP value and antifriction behaviour of oil was dependent on the crystal structure of C-60/C-70 powder, but independent of the spherical molecular structure of C-60 or C-70 The burnishing experimental results also proved that the antifriction behaviour was determined by the crystal structure and had no relation to the molecular structure. It was also found that fullerenes possessed some physical properties similar to those of graphite. Since the formation of compact fullerenes with high shear strength during friction can be effectively prevented by some other lubricants, it is suggested that fullerenes should be mixed with other lubricants for tribological application.