scholarly journals Bidisperse Magnetic Particles Coated with Gelatin and Graphite Oxide: Magnetorheology, Dispersion Stability, and the Nanoparticle-Enhancing Effect

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 714 ◽  
Author(s):  
Yu Fu ◽  
Jianjun Yao ◽  
Honghao Zhao ◽  
Gang Zhao ◽  
Zhenshuai Wan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Graphite Oxide ◽  
Self Assembly ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Dispersion Stability ◽  
Functional Coating ◽  
Enhancing Effect ◽  
Mr Fluids

The magnetorheology and dispersion stability of bidisperse magnetic particles (BMP)-based magnetorheological (MR) fluids were improved by applying a novel functional coating composed of gelatin and graphite oxide (GO) to the surfaces of the micron-sized carbonyl iron (CI) and nanoparticles Fe3O4. Gelatin acted as a grafting agent to reduce the aggregation and sedimentation of CI particles and prevent nanoparticles Fe3O4 from oxidation. In addition, a dense GO network on the surface of gelatin-coated BMP was synthesized by self-assembly to possess a better MR performance and redispersibility. The rheological properties of MR fluids containing dual-coated BMP were measured by a rotational rheometer under the presence of magnetic field and their dispersion stability was examined through sedimentation tests. The results showed that CI@Fe3O4@Gelatin@GO (CI@Fe3O4@G@GO) particles possessed enhanced MR properties and dispersion stability. In addition, the nanoparticle-enhancing effects on the dispersion stability of BMP-based MR fluids were investigated using Monte Carlo simulations.

Encapsulation of Carbonyl Iron Particles with Poly(Vinyl Butyral) and their Magnetorheology

2007 ◽  
Vol 334-335 ◽  
pp. 193-196
Author(s):  
Jae Lim You ◽  
B.J. Park ◽  
I.B. Jang ◽  
Hyoung Jin Choi
Keyword(s):  
Magnetic Field ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Mineral Oil ◽  
Iron Particles ◽  
Carrier Liquid ◽  
Mr Fluids ◽  
Fluid Systems ◽  
Ft Ir ◽  
Vinyl Butyral

To enhance dispersion stability of magnetorheological (MR) fluids, hybrid magnetic particles of carbonyl iron (CI)/ poly(vinyl butyral) (PVB) with core/shell microstrcutre (CI-PVB) were prepared, since pure magnetic CI based MR fluid systems show severe sedimentation of the CI particles due to the large density mismatch with the carrier liquid and difficulties in redispersion after caking. The composite particles of CI-PVB have a lower density than that of the pure CI particles, while exhibiting almost original magnetic property of the CI. Both CI and CI-PVB particles were dispersed in mineral oil (20 vol%) and their MR characteristics were examined via a rotational rheometer with a magnetic field supplier. Various characterizations of the CI-PVB particles were performed via SEM, TEM and FT-IR. Both yield stress and flow curve of shear stress as a function of shear rate of the MR fluids were investigated under applied magnetic field strengths.

scholarly journals Self-assembly of smallest magnetic particles

2015 ◽  
Vol 112 (47) ◽  
pp. 14484-14489 ◽  
Author(s):  
Sara Mehdizadeh Taheri ◽  
Maria Michaelis ◽  
Thomas Friedrich ◽  
Beate Förster ◽  
Markus Drechsler ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Data Storage ◽  
Self Assembly ◽  
Magnetic Particles ◽  
Dipole Interaction ◽  
The Self ◽  
Magnetic Structures ◽  
Medical Technologies ◽  
1D Chains

The assembly of tiny magnetic particles in external magnetic fields is important for many applications ranging from data storage to medical technologies. The development of ever smaller magnetic structures is restricted by a size limit, where the particles are just barely magnetic. For such particles we report the discovery of a kind of solution assembly hitherto unobserved, to our knowledge. The fact that the assembly occurs in solution is very relevant for applications, where magnetic nanoparticles are either solution-processed or are used in liquid biological environments. Induced by an external magnetic field, nanocubes spontaneously assemble into 1D chains, 2D monolayer sheets, and large 3D cuboids with almost perfect internal ordering. The self-assembly of the nanocubes can be elucidated considering the dipole–dipole interaction of small superparamagnetic particles. Complex 3D geometrical arrangements of the nanodipoles are obtained under the assumption that the orientation of magnetization is freely adjustable within the superlattice and tends to minimize the binding energy. On that basis the magnetic moment of the cuboids can be explained.

scholarly journals Gelatine-Coated Carbonyl Iron Particles and Their Utilization in Magnetorheological Suspensions

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2503
Author(s):  
Tomas Plachy ◽  
Patrik Rohrer ◽  
Pavlina Holcapkova
Keyword(s):  
Magnetic Field ◽  
Liquid Medium ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Silicone Oil ◽  
Rheological Parameters ◽  
Iron Particles ◽  
Magnetorheological Suspensions ◽  
Magnetorheological Suspension ◽  
Dynamic Yield

This study demonstrates the formation of biocompatible magnetic particles into organized structures upon the application of an external magnetic field. The capability to create the structures was examined in silicone-oil suspensions and in a gelatine solution, which is commonly used as a blood plasma expander. Firstly, the carbonyl iron particles were successfully coated with gelatine, mixed with a liquid medium in order to form a magnetorheological suspension, and subsequently the possibility of controlling their rheological parameters via a magnetic field was observed using a rotational rheometer with an external magnetic cell. Scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis confirmed the successful coating process. The prepared magnetorheological suspensions exhibited a transition from pseudoplastic to Bingham behavior, which confirms their capability to create chain-like structures upon application of a magnetic field, which thus prevents the liquid medium from flowing. The observed dynamic yield stresses were calculated using Robertson–Stiff model, which fit the flow curves of the prepared magnetorheological suspensions well.

Synthesis and characterization of novel flake-shaped carbonyl iron and water-based magnetorheological fluids using laponite and oleic acid with enhanced sedimentation stability

2021 ◽  
pp. 1045389X2098700
Author(s):  
Chandra Shekhar Maurya ◽  
Chiranjit Sarkar
Keyword(s):  
Magnetic Field ◽  
Oleic Acid ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Carbonyl Iron ◽  
Vibration Isolation ◽  
Zero Field ◽  
Sedimentation Stability ◽  
Mr Fluids ◽  
Water Based

In this study, micron-sized flake shaped carbonyl iron (CI) water-based MR fluids were prepared with adding laponite and oleic acid as an additive and surfactant, respectively. The MR suspensions are comprised of the fixed CI particles and water weight %, while weight % of laponite and oleic acid changes from 1 to 3 wt% and 0.5 to 1.5 wt%, respectively. The remarkable enhancement in magnetorheological properties was obtained with improved sedimentation stability for CI/water MR suspensions with the addition of laponite and oleic acid. It was found that at the lowest magnetic field strength, the higher laponite concentration is effective, while at the highest magnetic field strength, the smaller concentration was effective. It was because of the combined effect of the field-induced CI chains and the laponite clay gel network. Its storage moduli showed a stable plateau area for whole angular frequencies, suggesting distinguished solid-like behavior of the MR fluid. Finally, a novel correlation was obtained between the initial settling rate of the CI particles and magnetorheological behavior of CI/laponite/OA MR suspensions with 1 wt% laponite and 0.5 wt% oleic acid, which has less zero-field, high on-state shear stress with enhanced sedimentation stability. The prepared MR fluids are a reliable industrial application vibration-isolation, clutch, and brake.

MR FLUIDS WITH NANO-SIZED MAGNETIC PARTICLES

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3167-3172 ◽  
Author(s):  
Cl. Kormann ◽  
H.M. Laun ◽  
H.J. Richter
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Elevated Temperatures ◽  
Shear Rates ◽  
Mr Fluids ◽  
High Shear Rates ◽  
Moderate Magnetic Field ◽  
Actuator Design ◽  
The Magnetic Field

Recently magnetorheological fluids with nanosized magnetic ferrite particles have become available. Their composition, rheological and magnetic properties are described. A comparison with conventional MR fluids based on micron-sized particles is given. The yield stress of nano-MR fluids can be increased by a moderate magnetic field (0,2 T) by 4000 Pa. It can be modulated by the magnetic field with a response time of less than 5 ms. Details are given on the long term thermal stability at 150 °C, on flow properties at elevated temperatures and at high shear rates. Design principles for MR fluid actuator design are outlined.

scholarly journals Enhanced Magnetorheological Performance of Carbonyl Iron Suspension Added With Barium Ferrite Nanoparticle

2021 ◽  
Vol 8 ◽  
Author(s):  
Hyo Seon Jang ◽  
Qi Lu ◽  
Hyoung Jin Choi
Keyword(s):  
Magnetic Field ◽  
Carbonyl Iron ◽  
Barium Ferrite ◽  
Flow Behavior ◽  
Vibrating Sample Magnetometry ◽  
Mr Fluid ◽  
Mr Fluids ◽  
Ferrite Nanoparticle ◽  
The Magnetic Field ◽  
Mr Characteristics

Hard-magnetic barium ferrite (BF) nanoparticles with a hexagonal plate-like structure were used as an additive to a carbonyl iron (CI) microparticle-based magnetorheological (MR) fluid. The morphology of the pristine CI and CI/BF mixture particles was examined by scanning electron microscopy. The saturation magnetization and coercivity values of each particle were measured in the powder state by vibrating sample magnetometry. The MR characteristics of the CI/BF MR fluid measured using a rotation rheometer under a range of magnetic field strengths were compared with those of the CI-based MR fluid. The flow behavior of both MR fluids was fitted using a Herschel–Bulkley model, and their stress relaxation phenomenon was examined using the Schwarzl equation. The MR fluid with the BF additive showed higher dynamic and elastic yield stresses than the MR fluid without the BF additive as the magnetic field strength increased. Furthermore, the BF nanoparticles embedded in the space between the CI microparticles improved the dispersion stability and the MR performance of the MR fluid.

Magnetorheological Fluids Behaviour in Tension Loading Mode

2008 ◽  
Vol 47-50 ◽  
pp. 242-245 ◽  
Author(s):  
Saiful Amri Mazlan ◽  
Ahmed Issa ◽  
Abdul Ghani Olabi
Keyword(s):  
Magnetic Field ◽  
Tensile Stress ◽  
Magnetic Particles ◽  
Electrical Current ◽  
High Ratio ◽  
Solid Particles ◽  
Mr Fluid ◽  
Carrier Fluid ◽  
Mr Fluids ◽  
Water Based

In this paper, the behaviours of three types of MR fluids under quasi-static loadings in tension mode were investigated. One type of water-based and two types of hydrocarbon-based MR fluids were activated by a magnetic field generated by a coil using a constant value of DC electrical current. Experimental results in terms of stress-strain relationships showed that the MR fluids had distinct unique behaviours during the tension process. A high ratio of solid particles to carrier liquid in the MR fluid is an indication of high magnetic properties. The water-based MR fluid had a relatively large solid-to-liquid ratio. At a given applied current, a significant increase in tensile stress was obtained in this fluid type. On the other hand, the hydrocarbon-based MR fluids had relatively lower solid to liquid ratios, whereby, less increases in tensile stress were obtained. The behaviours of MR fluids were dependent on the relative movement between the solid magnetic particles and the carrier fluid. A complication occurs because, in the presence of a magnetic field, there will be a tendency of the carrier fluid to stick with the magnetic particle

Behavior of Magnetorheological Fluids Employing Carrier Fluids Certified for Landing Gear Use

2008 ◽  
Author(s):  
Louise Ahure´ ◽  
Norman M. Wereley
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Landing Gear ◽  
Small Scale ◽  
Hydraulic Systems ◽  
Sedimentation Analysis ◽  
Mr Fluids ◽  
Helicopter Landing ◽  
Different Characteristics ◽  
Potential Use

Magnetorheological (MR) fluids were prepared in order to investigate their performance for potential use in landing gear hydraulic systems, such as shock struts. MR fluids formulated here utilized three hydraulic oils certified for use in landing gear, two different average diameters of spherical magnetic particles, and a Lecithin surfactant. The fluids were characterized in order to measure and analyze their rheological behavior. Therefore, different characteristics were taken into consideration, such as 1) magnetorheology as a function of magnetic field, 2) cycling of a small-scale damper undergoing sinusoidal excitations at frequencies of 2.5 and 5 Hz, and 3) sedimentation analysis conducted with an inductance-based sensor. The goal of this research is to analyze the performance of these particular MR fluids, to compare their behavior to standard commercial MR fluids, and to determine their feasibility for use in helicopter landing gear.

scholarly journals STRONG MAGNETIC FIELD INDUCED SEGREGATION AND SELF-ASSEMBLY OF MICROMETER SIZED NON-MAGNETIC PARTICLES

2010 ◽  
Vol 23 ◽  
pp. 199-214 ◽  
Author(s):  
Zhi Sun ◽  
Muxing Guo ◽  
Jef Vleugels ◽  
Omer Van der Biest ◽  
Bart Blanpain
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Self Assembly ◽  
Magnetic Particles
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