The Tribological Properties of Oils Added with Diamond Nano-Particles

A technique of relative optical interference intensity (ROII) and a high-precision force measuring system were used to measure film thickness and friction force of the oils added with ultra-fine diamond powder (UDP) in the nano-scale. The results show that the oil containing UDP nano-particles forms a thicker film than does the pure base oil. In the rubbing process, the hard spherical UDP nano-particles plow the two surfaces and produce many smooth micro-grooves. The friction force decreases with sliding distance. The possible mechanisms for such reduction and physical model of diamond nano-particles as additives in oils are discussed.