Abstract： To research the influence of coating layer thickness of particles on property of magnetorheological fluid (MRF), the magnetic particles with different thickness of coating layer were prepared by changing the concentration of PVA in solution and different types of MRF were prepared. The particle morphology, size and magnetic property were characterized， and the viscosity, shear yield stress and stability of different types of MRF were tested. The results show that different thickness of coating layer on surface of particles has less effect on viscosity without magnetic field, but leads the shear yield stress change from weak to strong and then weak again with the increase of magnetic field. The stability of MRF becomes worse due to the existence of big agglomerated particles when the thickness of particle coating layer gets thick.

Keywords: magnetorheological fluid; particle coating; viscosity without magnetic field; shear yield stress; stability property