Effect of silica morphology on rheological properties and stability of magnetorheological fluid

Abstract

SiO2 is commonly used as an abrasive in optical devices and magnetorheological (MR) fluid. In this study, MR fluid with composite and free-state SiO2 were prepared. Composite magnetic particles of CIP@SiO2 were synthesized using the sol-gel method with tetraethyl orthosilicate (TEOS) as the silicon source. Performance test results showed that CIP@SiO2 MR fluid exhibited superior mechanical properties compared with CIP MR fluid under zero magnetic field conditions. However, under the influence of a magnetic field, the SiO2 shell weakened the response of CIP@SiO2 MR fluid to the magnetic field, whereas CIP MR fluid demonstrated better rheological properties. The addition of free-state SiO2 to CIP MR fluid significantly improved its rheological performance. At a volume fraction of 6% SiO2, the shear stress and viscosity reached their maximum values, and further increasing the volume fraction to 8% resulted in a noticeable decrease in rheological behavior. Stability improved with an increase in magnetizable particle content. The stability of CIP MR fluid at the same concentration was superior to that of CIP@SiO2 MR fluid, while free-state SiO2 had a notable enhancing effect on stability. Therefore, when SiO2 exists as a free-state abrasive, the rheological properties and stability of the MR fluid considerable improve.