Effect of Particle Concentration on Lubricating Properties of Magnetic Fluid

摘要

The tribological properties of two mineral oil with different viscosities (219 and 10.3 mPa·s) are compared and analyzed using four ball tester. To improve the tribological properties of low viscosity mineral oil, magnetic nanoparticles are added. The concentration of magnetic nanoparticles was optimized for a minimum friction and wear. At optimum volume percentage (0.8 vol.%) of magnetic nanoparticles in low viscosity mineral oil, antifriction and anti-wear properties enhanced by 36% and 49%, respectively. Likewise, at optimum concentration of magnetic nanoparticles, these attributes are improved by 20% and 43% respectively, in high viscosity mineral oil. The reduction in the coefficient of friction is explained by considering the ball bearing effect of magnetic nanoparticles. The lubrication mechanism was studied using scanning electron microscope and atomic force microscope, which shows the synergistic effect of polishing and mending effect.