Friction and wear of magnetorheological fluid under magnetic field

The continuously adjustable magnetic field was performed by modifying of a four-ball tribological tester. The tribological properties of magnetorheological fluid (MRF) were studied under magnetic field. The worn surfaces of the steel balls lubricated with MRF were observed by using a scanning electron microscope (SEM). It is found that the MRF shows a controlled tribological property. Under 0.12 T of magnetic induction, the friction coefficient lubricated with MRF is four times as large as that without magnetic field. The worn surfaces, lubricated by MRF under the effect of a magnetic field, change from circle or ellipse to irregular rectangle and the diameter of wear scar decreases. Under the successive variable magnetic field, the friction coefficient increases with the enhancement in the magnetic field, and it decreases with the weakening of the magnetic field.

► Magnetorheological fluid (MRF) exhibits controlled tribological properties.
► The changes of friction coefficient are in accord with that of the magnetic field.
► The friction coefficient lubricated with MRF in 0.12 T is the quadruple of that in 0 T.
► The morphology of worn surfaces is changed.
► The diameter of wear scar is smaller in 0.12 T than that in 0 T.