Magnetorheological study of core-shell structured carbonyl iron/2-D graphene oxide microparticles suspensions with improved sedimentation stability

This study aims to assess the rheological and stabilization characteristics of magnetorheological (MR) suspension by dispersing core-shell particles (graphene oxide (GO) as a shell and carbonyl iron (CI) as a core). A simple wet stirring technique was utilized to achieve the grafting of bare carbonyl particles (CIPs) with para-aminobenzoic acid (g-CIPs), and graphene oxide with concentrations of 1 and 2 wt%. The morphological, magnetization and elemental characteristics of prepared core-shell particles were analyzed by Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS), powder X-Ray diffraction (XRD), Raman Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The encapsulation of grafted carbonyl iron particles with graphene oxide enhanced the surface roughness, while the structure of carbonyl iron particles retained its spherical shape. The presence of core-shell particles increased the affinity between the suspended particles and carrier oil, leading to better stability against sedimentation. The stability of prepared MR suspensions was examined by the visualization technique in which graphene oxide encapsulated carbonyl iron particles (GO@gCIPs) showed remarkable improvement in sedimentation stability. The MR suspension is based on 1 wt% graphene oxide coated carbonyl iron particles (GO@g-CIPs-1) exhibits a sedimentation ratio of 44%, which is higher than that of the MR suspension based on 2 wt% graphene oxide coated carbonyl iron particles (GO@g-CIPs-2) (32%) and the MR suspension containing bare CIPs (20%). Finally, the magnetorheological study was carried out using a rotational rheometer. GO@g-CI based MR suspensions demonstrated a promising magnetorheological performance and identical MR characteristics, with varying yield stress.