Enhanced Magnetorheological Behavior of a Carbonyl‐Iron‐Based Fluid via Addition of Fe₃O₄/Halloysite‐Nanotube Composite Particles

Abstract

Composite additives for enhancing the yield stress, sedimentation stability, and long-term reversibility of bidisperse magnetorheological fluids (MRFs) are reported herein. The design and introduction of magnetic Fe 3 O 4 /halloysitenanotube (HNT) composite additives to carbonyl-iron (CI)-based MRFs are described, and the effects of Fe 3 O 4 /HNT addition on the MRF behavior are elucidated. The rheological, viscoelastic, and cyclic reversibility analyses of the bidisperse Fe 3 O 4 /HNT-CI MRFs indicate that the MR performance increases and subsequently decreases with the increasing content of the Fe 3 O 4 /HNTs. The MRF containing 1.0 wt% Fe 3 O 4 /HNTs shows optimal MR properties and longterm reversibility. Under a magnetic field, the 1.0 wt% Fe 3 O 4 /HNTs are embedded in the interstices of the magnetic chains, enhancing the magnetic dipole-dipole interactions between the particles, strengthening the rigidity of the magnetic chains, and increasing the yield stress of the MRF. The Fe 3 O 4 /HNTs are adsorbed on the surfaces of the CI particles in the absence of a magnetic field, occupying the free space between the CI particles and forming support structures, which prevents aggregation and improves sedimentation stability. Moreover, the designed MRFs respond quickly to magnetic field switching and exhibit enhanced long-term reversibility.

Enhancement of Magnetorheological Fluids with Size and Morphology—Optimized Fe3O4 Nanoparticles: Impacts on Rheological Properties and Stability

“…Based on previous work on Fe 3 O 4 -halloysite composites and their concentrations [ 18 ], we further investigated the impact of Fe 3 O 4 particle size and morphology on CI-MRF. This study synthesized Fe 3 O 4 NPs using a solvothermal method, varying the particle sizes and morphologies by employing different surfactants.…”