Effect of interfacial shear strength between magnetic particles and carrier liquid on rheological properties of magnetorheological fluids

The interfacial mechanical strength between carbonyl iron particles (CIPs) and carrier liquid is one of the key factors for the rheological properties of magnetorheological (MR) fluids. Here, the microstructure and shear properties of the interface between CIPs and dimethyl silicone oil (DSO) are studied using molecular dynamics simulation. Results indicate that there is strong adhesive strength between Fe atoms on the surface of CIPs and DSO molecular chains during the shearing process. For the MR fluids with DSO viscosity of 50 and 200 mPa⋅s, the DSO molecular structure between CIPs is easy to break out under shear deformation owing to the short DSO chains. While as for the Fe/DSO/Fe model with DSO viscosity of 350 and 500 mPa⋅s, the interfacial shear strength is greatly higher than that with low viscosity DSO due to the entanglement between long chains of DSO. Finally, MR fluids with different viscosity DSO are prepared for rheological tests to verify our simulation results. By combining simulation and experiment, the high interfacial shear strength can improve the rheological properties of the MR fluids. These insights reveal the relationship between the interfacial shear properties of the CIPs/DSO and the rheological properties of MR fluids.