Abstract
Magnetorheological greases (MRGs) is a viscoelastic suspension comprised of carbonyl iron (CI) particles in a thixotropic medium; grease, which able to solve the instability problem that occurs in oil medium like MRFs. The primary purpose introduction of superparamagnetic nanoparticles γ-Fe2O3 in MRGs suspension is to investigate the effect of additives toward MRGs characteristics. Two types of MRGs suspension with and without nanoparticles γ-Fe2O3 were prepared in the same CI particles concentration for comparison purpose. It was observed that MRGs with incorporated of 1 wt% nanoparticles γ-Fe2O3 showed an increment regarding magnetic properties. In the meantime, the off-state viscosity of MRGs containing nanoparticles γ-Fe2O3 was reduced, however, increased during on-state condition. This fact indicates that the interspaces between CI particles are filled by the nanoparticles γ-Fe2O3. Therefore, the introduction of the nanoparticles indirectly improved the MRGs properties.
Highlights
Magnetorheological (MR) materials have been attracting researcher intention in last six decades
The primary goal of this study is to investigate the effect of superparamagnetic nanoparticles γ-Fe2O3 towards Magnetorheological greases (MRGs) characteristics
The hysteresis loop of MRGs with nanoparticles (MRGN) is very narrow with a small coercivity compared to MRGs which indicates that nanoparticles γFe2O3 behave as soft materials that important for reversibility of MR performance [11]
Summary
Magnetorheological (MR) materials have been attracting researcher intention in last six decades. This material comprises of non-magnetic viscoelastic materials such as fluids, greases, plasticine, and elastomer, filled with micron-sized soft magnetic materials [1,2,3]. Among several types of MR materials, MR fluids (MRFs) have been most attractive due to their broad application. According to Chand et al [5], MRFs has been facing some problems such as settling rate and fluid leaking. These problems can be overcome by introducing thixotropic materials such as greases as the matrix carrier [6]
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