A comparison of field-dependent rheological properties between spherical and plate-like carbonyl iron particles-based magneto-rheological fluids

Abstract

This work proposes different sizes of the plate-like particles from conventional spherical carbonyl iron (CI) particles by adjusting milling time in the ball mill process. The ball mill process to make the plate-like particles is called a solid-state powder processing technique which involves repeated welding, fracturing and re-welding of powder particles in a high-energy ball mill. The effect of ball milling process on the magnetic behavior of CI particles is firstly investigated by vibrating sample magnetometer. It is found form this investigation that the plate-like particles have higher saturation magnetization (about 8%) than that of the spherical particles. Subsequently, for the investigation on the sedimentation behavior the cylindrical measurement technique is used. It is observed from this measurement that the plate-like particles show slower sedimentation rate compared to the spherical particles indicating higher stability of the MR fluid. The field-dependent rheological properties of MR fluids based on the plate-like particles are then investigated with respect to the milling time which is directly connected to the size of the plate-like particles. In addition, the field-dependent rheological properties such as the yield stress are evaluated and compared between the plate-like particles based MR fluids and the spherical particles based MR fluid. It is found that the yield shear stress of the plate-like particles based MR fluid is increased up to 270% compared to the spherical particles based MR fluid.

A comparative work on the magnetic field-dependent properties of plate-like and spherical iron particle-based magnetorheological grease

“…From the observation, the MRG-P 30 exhibited a higher apparent viscosity than the MRG-S 30. This outcome was expected to occur in the MRG-P because of the larger surface contact area, which led to the strong attraction between the plate-like CI particles [ 13 ]. In addition, the strong attraction between CI particles led to their rearrangement into lines to form chain structures, that were parallel to the applied magnetic field.…”

“…The plate-like CI particles were obtained from a milling process utilizing a rotary ball mill (QM-5 model from Tencan Company). The details of the procedure were undertaken according to the method described by Shilan et al [ 13 ]. In this work, the duration of the milling process was 40 hours.…”

“…In addition, it was shown that this behaviour was saturated at a low magnetic field intensity of 80 kA m -1 , and that the sedimentation rate was significantly decreased compared to MR fluids consisting of spherical-shaped magnetisable particles. Shilan et al [ 13 ] reported on the rheological properties and sedimentation of MR fluids based on plate-shaped particles and compared them with spherical particle-based MR fluids. Their results indicated that the magnetic saturation of the plate-like particles was 8% higher than that of the spherical particles.…”

“…As surveyed from the above literature, studies on the comprehensive effects of the shape of particles on the magnetic field-dependent rheological performance of MR grease are considerably rare. To the best of the authors’ knowledge, studies into the effects of different particle shapes on the magnetic field-dependent performance of MR grease so far have been undertaken through simulation only [ 14 ], despite many works on the plate-like iron particle-based MR fluids via both simulation and experiment [ 10 – 13 , 16 , 18 ]. Consequently, the main technical contribution of this work was to experimentally investigate and compare the magnetic field-dependent rheological properties of MR grease with regard to two different particle shapes, namely plate-like CI particles and spherical CI particles.…”

Role of Additives in Enhancing the Rheological Properties of Magnetorheological Solids: A Review

“…However, MR fluids exhibit distinct shortcomings. For example, the long‐term stability against sedimentation of the particles suspended in MR fluids is still a major issue because particle sedimentation can degrade the MR performance . Few studies has been conducted to overcome the sedimentation problem in the MR fluids such as coating of magnetic nanoparticles using polystyrene by Kim et al, utilization of bi‐diperse particle and inclusion of magnetic nanoparticles additive into MR fluids .…”