Tribological characteristics of paraffin liquid with nanodiamond based on the scuffing life and wear amount

In order to develop an eco-friendly lubricant, nanodiamonds were selected and added to a paraffin liquid by a matrix synthesis method. This method can maintain good dispersibility without cohesion and avoid precipitation for an extended period of time. The lubricity of dispersed oils with different amounts of nanodiamond particles was compared using both constant load and step loading on ball-on-disk type tests. Friction characteristics, wear amount, and scuffing life were determined. During the tests, the temperatures of oils were monitored in order to verify the heat dispersion rates of oils that contained nanodiamond. Several hypotheses are presented to explain the results of this work. By the addition of nanodiamond particles, the coefficient of friction may have been reduced due to their octagonal, almost spherical shape which can act as rolling contact elements between two surfaces. Also, it is proposed that nanodiamond can support the load between two sliding surfaces because of its high hardness value. Because the nanodiamond has the ability to disperse the generated frictional heat, it leads to increase the scuffing life.