Improvement of magnetorheological greases with superparamagnetic nanoparticles

¹ Malaysia Japan International Institute of Technology, Universiti Teknologi Malaysia (UTM), Jalan Sultan Yahya Petra, 54100 Kuala Lumpur, Malaysia
² Mechanical Engineering Department, Faculty of Engineering, Universitas Sebelas Maret (UNS), Jl. Ir. Sutami 36A, Kentingan Surakarta, 57126, Central Java, Indonesia
³ National Center for Sustainable Transportation Technology (NCSTT), Indonesia
⁴ Mechanical Engineering Department, Inha University, Incheon, Republic of Korea

^* Corresponding author: ubaidillah_ft@staff.uns.ac.id; amri.kl@utm.my

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.