The Study of Magnetorheology of Iron Oxide Nanowires

Abstract

In this work, circular Fe3O4particles with a diameter of 24 nm and quasicircular Fe3O4particles with a diameter of 10 nm were synthesized using peptization and coprecipitation methods, respectively. The coprecipitated particles were further formed into Fe3O4nanowires at high temperature and high pressure in a strongly alkaline environment. The optimal environment for forming nanowire was 15 m (molality) NaOH at 120°C for three days; the resulting proportional relationship between its width and its height, the aspect ratio, was 50.5/1. In the second part of this study, the nanoparticles and nanowire were dispersed in silicon oil and formed into magnetorheological (MR) fluids of different concentrations, before undergoing various MR tests—a shear test, a compression test, and a creep recovery test. The results revealed that the MR performance of nanowire fluid was better than that of circular particle fluid, in terms of yield stress (35 Pa versus 60 Pa), compression displacement (Δd) (0.19 mm versus 0.44 mm), and creep recovery ratio (82% versus 48%). The experimental results conclude that the nanowire network is more robust than the nanoparticle network. The test of the storage shelf time revealed that 12 wt% nanowire fluid retained more than 80% of its original yield stress after three months, indicating slight precipitation in the nanowire fluid. In summary, the nanowire MR fluid had a stronger MR effect than traditional MR fluid that was prepared with spherical MR particles.