Tribological performance of freeze-drying nano-copper particle as additive of paroline oil

Abstract

Abstract Monodispersed nano-copper particles were prepared, and the optimized method of preparation procedure was established through orthogonal experiments under four different factors. The experimental results show that the particle size of freeze-dried nano-copper particles can be adjusted by rotational speed, freezing rate, types of active agents and freezing mode, and freezing mode is the most important among all of the four factors. Tribological results of the nano-copper particles from the best optimized procedure can be improved 5%–10% than that of pure paroline oil and the lowest coefficient of friction 0.12 can be obtained for the sample of 0.05 wt%. The lubrication mechanism mostly attributed to the appropriate concentration of copper particles filling the surface pits, which is beneficial for the improvement of the tribological performance.