This review of MRF (magnetorheological fluids or MR fluids) brings out the challenges in methods of preparation, difficulties encountered in storage and use, and possible solutions to overcome the challenges. Magnetorheological fluid in the rheological fluid domain has found use due to its ability to change its shear strength based on the applied magnetic field. Magnetorheological fluids are composed of magnetizable micron-sized iron particles and a non-magnetizable base or carrier fluid along with additives to counter sedimentation and agglomeration. Magnetorheological fluids can respond to external stimuli by undergoing changes in physical properties thus enabling several improved modifications in the existing technology enhancing their application versatility and utility. Thus, magnetorheological fluid, a rheological material whose viscosity undergoes apparent changes on application of magnetic field, is considered as a smart material. Such materials can be used for active and semi-active control of engineering systems. Many studies on the designs of systems incorporating MR fluids, mainly for vibration control and also for other applications including brakes, clutches, dynamometers, aircraft landing gears, and helicopter lag dampers, have emerged over last couple of decades. However, the preparation as well as the maintenance of magnetorheological fluids involves several challenges. Sedimentation is a major challenge, even when stored for moderate periods of time. A comprehensive review is made on the problems confronted in the preparation of magnetorheological fluids as well as sustenance of the properties, for use, over a long period of time. Other problems encountered include agglomeration and in-use thickening (IUT) as well as rusting and crusting. Of interest is the mitigation of these problems so as to prepare fluids with satisfactory properties, and such solutions are reviewed here. The control of magnetorheological fluids and the applications of interest are also reviewed. The review covers additives for overcoming challenges in the preparation and use of magnetorheological fluids that include incrustation, sedimentation, agglomeration, and also oxidation of the particles. The methodology to prepare the fluid along with the process for adding selected additives was reviewed. The results showed an improvement in the reduction of sedimentation and other problems decreasing comparatively. A set of additives for addressing the specific challenges has been summarized. Experiments were carried out to establish the sedimentation rates for compositions with varying fractions of additives. The review also analyzes briefly the gaps in studies on MR fluids and covers present developments and future application areas such as haptic devices.

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A review of challenges and solutions in the preparation and use of magnetorheological fluids

Magnetic Soft Matter is a rapidly evolving discipline with fundamental and practical interest. This is due to the fact that its physical properties can be easily controlled through external magnetic fields. In this review paper, we revisit the most recent progress in the field (since 2010) emphasizing the rheological properties of these fascinating materials. New formulations and flow kinematics are discussed. Also, new members are integrated into the long-lived magnetorheology family and suggestions are provided for future development.

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Magnetorheology: a review.

Effect of a hard magnetic particle additive on rheological characteristics of microspherical carbonyl iron-based magnetorheological fluid

The graphene oxide-coated iron oxide/silica core/shell nanoparticles (Fe3O4/SiO2/GO NPs) are successfully fabricated and adopted as the dual stimuli-responsive smart fluid. The Fe3O4/SiO2/GO NPs exhibit both electrorheological (ER) and magnetorheological (MR) characteristics, attributed to the SiO2/GO layer in the shell part and Fe3O4 in the core part, respectively. Particularly, the ER efficiency of the Fe3O4/SiO2/GO NPs-based ER fluid is ca. 191 at the applied electric field of 3 kV mm–1. Moreover, the MR performance of the Fe3O4/SiO2/GO NPs-based MR fluid is significantly enhanced up to 135-fold at the applied magnetic field of 1 T compared to the zero-field stress. Furthermore, it is remarkable that the Fe3O4/SiO2/GO NPs represent high colloidal stability and outstanding antisettling property because of the electrostatic repulsion between oxygen functional groups on GO nanosheets and the relatively low density compared with other magnetic particles. Dual stimuli-responsive characteristics in addition ...

Dual Stimuli-Responsive Smart Fluid of Graphene Oxide-Coated Iron Oxide/Silica Core/Shell Nanoparticles

Iron nanoparticles-based magnetorheological fluids: A balance between MR effect and sedimentation stability

Rod-like hard-magnetic nanoparticles of γ-Fe2O3 were used as an additive to a soft magnetic carbonyl iron (CI) microsphere-based magnetorheological (MR) suspension to improve the dispersion stability of the MR fluid and enhance its MR performance. The morphology of the pure CI microspheres and CI/γ-Fe2O3 mixture particles were examined by scanning electron microscopy. The MR properties of pure CI and CI/γ-Fe2O3 mixtures were measured from steady and oscillatory tests under different magnetic field strengths. The results showed that the CI/γ-Fe2O3 MR fluid exhibited higher yield behaviors with an enhanced MR effect than that of the pure CI MR fluid due to the increased magnetic properties. Physically attached γ-Fe2O3 nanoparticles onto the surface of micron-sized CI particles improved not only MR performance but also dispersion stability of the MR particles.

Enhanced magnetorheology of soft magnetic carbonyl iron suspension with hard magnetic γ-Fe 2 O 3 nanoparticle additive

We report a facile synthesis of Pickering emulsion polymerized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polystyrene (PEDOT:PSS/PS) composite particles and their electro-responsive electrorheological (ER) characteristics when dispersed in silicone oil. The PEDOT:PSS particles act both as a solid surfactant for the Pickering emulsion polymerization and as an electro-responsive activator for PEDOT:PSS/PS composite particles. The morphology, chemical structure, and thermal properties of the synthesized PEDOT:PSS/PS composite particles were determined by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. Moreover, the formation of chain structures by the dispersed particles was confirmed directly by optical microscopy. The rheological response of PEDOT:PSS/PS-based ER fluid in the presence of an electric field, examined using a rotational rheometer, represented ER effects with typical Bingham fluid behavior.

Pickering emulsion polymerized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polystyrene composite particles and their electric stimuli-response

Jung Hyun Kim

Papers

Enhanced magnetorheology of soft magnetic carbonyl iron suspension with hard magnetic γ-Fe 2 O 3 nanoparticle additive

Pickering emulsion polymerized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polystyrene composite particles and their electric stimuli-response