Preparation and Tribological Properties of Graphite Nanosheets as Additive in Liquid Paraffin

Graphite nanosheets with a mean diameter of 1 m and thickness of 10~20 nm were prepared by stirring ball milling. The morphology and structure of the graphite nanosheets were examined by means of scannine electron microscopy, transmission electron microscopy, and X-ray difraction. The effect of the graphite nanosheets as additive on the tribological properties of liquid paraffin was investigated using a four-ball test rig and a pin-on-disk friction and wear tester. The results showed that the graphite nanosheets prepared using the stirring ball milling retained the crystal structure of the natural graphite. They as the additive contributed to effectively improve the load-carrying capacity and antiwear ability of the base oil. The optimal concentration of the graphite nanosheets in the liquid paraffin was suggested to be about 50 ppm, at which the optimized friction-reducing and antiwear abilities were recorded.