Influence of Different Gradation Carbonyl Iron Particles on the Properties of Magneto-Rheological Fluids

Abstract

The influence of carbonyl iron particles sizes on the properties of magneto-rheological fluids (MRFs) were studied. Different-sized carbonyl iron magnetic particles were prepared by ball milling with different milling times. On this basis, different particle MRF were prepared The off-state viscosity and the shear stress of the above MRFs were characterised and studied by an advanced rotational rheometer system. The test results show that the off-state viscosity and the shear stress of single-particle MRFs were enhanced with increasing average carbonyl iron particle size at a constant magnetic field. The shear stresses of MRFs containing two or three different particle sizes were significantly improved compared with the MRFs containing only a single particle size. At a reasonable level of medium and small size carbonyl iron particle spread throughout the structure of the multiple-particle MRFs, the defects in the chain structure were remedied when a chain reaction occurred, and the mechanical properties of MRFs were enhanced. Meanwhile, increased mass fractions of the small size carbonyl iron particle resulted in a reduction in overall average particle size of MRFs, and the mechanical properties of MRFs were also reduced. The mechanical properties of multiple-particle MRFs were observed to be strongly dependent on the size and mass fraction of the medium and small carbonyl iron particles.