Investigation on the effects of doped dendritic Co particles on rheological property of magnetorheological gel

Abstract

Magnetorheological (MR) materials affect the performance of MR materials-based devices deeply. In order to overcome the disadvantage of magnetorheological fluid, such as particle sedimentation, in the application of earthquake resistance of buildings and bridges, this paper mixed micrometer sized soft magnetic particles with high viscosity polymer matrix instead of carrier fluid. What’s more, this work succeeded in synthesizing dendritic-like Co and a battery of magnetorheological gel (MRG) composites doped with dendritic-like Co for realizing enhanced MR behaviors. The dendritic-like Co possesses abundant secondary nano-branches and its mean diameter is about 10–16 μm, while the spherical CIP particles have a mean diameter of 5–8 μm. The rheology performance was tested under rotational shear mode. The result indicated that, viscosity of MRG increased along with the incorporation between Co and CIP. Moreover, when the applied magnetic fields were 300 mT and 400 mT, the maximum dynamic yield stress of sample 3, with 1.0 vol% dendritic-like Co, were 10.443 kPa and 14.85 kPa, ∼1.53 and ∼1.45 times higher than pure-CIPs whose yield stresses were 6.824 kPa and 10.255 kPa, respectively. This work putted forward a possible mechanism that enhanced MR properties in the dimorphic MRGs, and studied the stability of MRGs for a long time. The increased dynamic yield stress and stability characteristics are beneficial to improving the devices based on MRGs in the practical engineering application.