A magnetic super lattice

1987 ◽  
Vol 45 ◽  
pp. 360-361 ◽  
Author(s):  
M.D. Bentzon ◽  
J. v. Wonterghem ◽  
A. Thölén
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Carbon Film ◽  
Thick Layer ◽  
Amorphous Iron ◽  
Super Lattice ◽  
Carrier Liquid ◽  
Median Diameter

We report on the oxidation of a magnetic fluid. The oxidation results in magnetic super lattice crystals. The “atoms” are hematite (α-Fe2O3) particles with a diameter ø = 6.9 nm and they are covered with a 1-2 nm thick layer of surfactant molecules.Magnetic fluids are homogeneous suspensions of small magnetic particles in a carrier liquid. To prevent agglomeration, the particles are coated with surfactant molecules. The magnetic fluid studied in this work was produced by thermal decomposition of Fe(CO)5 in Declin (carrier liquid) in the presence of oleic acid (surfactant). The magnetic particles consist of an amorphous iron-carbon alloy. For TEM investigation a droplet of the fluid was added to benzine and a carbon film on a copper net was immersed. When exposed to air the sample starts burning. The oxidation and electron irradiation transform the magnetic particles into hematite (α-Fe2O3) particles with a median diameter ø = 6.9 nm.

Study on γ-Fe2O3 Magnetic Fluid by Thermal Oxidizing of Fe3O4 Nanoparticles

2015 ◽  
Vol 713-715 ◽  
pp. 2916-2919
Author(s):  
Hang Zheng ◽  
Hui Ping Shao ◽  
Zi Fen Zhao
Keyword(s):  
Surface Modification ◽  
Oleic Acid ◽  
Magnetic Nanoparticles ◽  
Saturation Magnetization ◽  
Sodium Oleate ◽  
Magnetic Fluid ◽  
Silicone Oil ◽  
Precipitation Method ◽  
Carrier Liquid ◽  
Co Precipitation

In this paper, Fe3O4magnetic nanoparticles were synthesized by chemical co-precipitation method and their surface was modified by sodium oleate. The γ-Fe2O3magnetic nanoparticles were achieved by thermal oxidizing of Fe3O4. The γ-Fe2O3magnetic fluid was prepared by using silicone oil as carrier liquid and oleic acid as surface modification agent, and the saturation magnetization of prepared γ-Fe2O3magnetic fluid hits 14.25emu/g.

Synthesis of Diester Based Magnetic Fluid

2012 ◽  
Vol 217-219 ◽  
pp. 721-724 ◽  
Author(s):  
Hai Rong Cui ◽  
Xue Feng Wang
Keyword(s):  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Research Field ◽  
Nano Particles ◽  
Molar Ratio ◽  
Engineering Research ◽  
Carrier Liquid ◽  
Proper Size ◽  
Environment Temperature ◽  
Magnetic Nano Particles

Diester based magnetic fluid is a novel intelligent material which use diester as carrier liquid and magnetic iron ore as magnetic nano-particles combined together with proper surfactant. Its specially unique characteristic contributes to wide applications in engineering research field such as magnetic fluid based seals, magnetic fluid based dampers and so on. This paper provides a method of diester-based magnetic fluid synthesis and analysis for the properties of prepared diester magnetic fluid as well as effective influencing parameters. The results show that for getting proper size and magnetization of magnetic particles, the proper reacted temperature is around 60~80°C, appropriate molar ratio of reacted solution is 1.75 and concentration of forerunner is about 0.6 mol/L. It is also found that the viscosity of diester-based magnetic fluid is decreased with environment temperature while the viscosity as well as saturation magnetization increases with the increment of density.

Superparamagnetic amorphous iron oxide nanowires self-assembled into ordered layered structures

RSC Advances ◽  
2015 ◽  
Vol 5 (77) ◽  
pp. 62563-62570 ◽  
Author(s):  
M. Iacob ◽  
D. Sirbu ◽  
C. Tugui ◽  
G. Stiubianu ◽  
L. Sacarescu ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Trichloroacetic Acid ◽  
Layered Structures ◽  
Oxide Nanoparticles ◽  
Amorphous Iron ◽  
Oxide Nanowires ◽  
Self Assembled

The thermal decomposition of μ3-oxo trinuclear iron(iii) acetate in presence of dodecylamine and oleic acid, in trichloroacetic acid at 320 °C was optimized to obtain iron oxide nanoparticles with pure nanowire morphology.

Effect of Surfactants on Modifying the Surface of Magnetic Nanoparticles by Thermal Decomposition

2011 ◽  
Vol 335-336 ◽  
pp. 951-955 ◽  
Author(s):  
Hui Ping Shao ◽  
Tao Lin ◽  
Ji Luo ◽  
Zhi Meng Guo
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Magnetic Nanoparticles ◽  
Decomposition Method ◽  
Magnetic Particles ◽  
Spherical Shape ◽  
Thermal Decomposition Method ◽  
Key Factor ◽  
Shape Of Particles ◽  
Shape And Size

The nanosize magnetic particles were synthesized by thermal decomposition method with size distribution in the range of 10 ~ 30 nm. Different category and quantity of surfactants were used modifying the surface of the synthesized nanoparticles to control the particles’ shape and size. Multi-shapes, such as uniformity cubic, mixture of spherical and cubic, and the similar chick footmarks, were acquired in our experiment by different surfactants. It indicates the surfactant is a key factor for the size and shape of particles. The surfactants of PVP and oleylamine made the particle shape be uniformity cubic; However, the particle partly behaved as spherical shape in the case of using PVP and oleic acid as surfactants.

scholarly journals Wave instability of a magnetic fluid surface at the boundary with water in an electric field

2021 ◽  
pp. 141-149
Author(s):  
В.С. Чеканов ◽  
Н.В. Кандаурова ◽  
Д.Л. Винокурский
Keyword(s):  
Oleic Acid ◽  
Electric Field ◽  
Interfacial Tension ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Protective Shell ◽  
Wave Instability ◽  
Electrode Layer ◽  
Weakly Conducting ◽  
Determining Factor

Свойства межфазной поверхности магнитной жидкости на границе с водой в электрическом поле изучались во многих работах. Были обнаружено изменение отражательной способности межфазной поверхности вода – магнитная жидкость в электрическом поле, что авторами связывается с образованием на межфазной границе слоя плотноупакованных частиц. По оптическим и электрическим измерениям оценена толщина d этого слоя. Интерес к этим эффектам, помимо чисто академического, связан с возможностью управления поведением межфазной границы раздела магнитного коллоида и гомогенной жидкости внешним электрическим полем, что представляет практический интерес, поскольку слой частиц магнетита на межфазной поверхности может быть интерпретирован как жидкая мембрана с особыми свойствами. Задача настоящего исследования – теоретически показать, что образование слоя частиц дисперсной фазы магнитной жидкости в электрическом поле и связанное с этим уменьшение межфазного натяжения является определяющим фактором для развития волновой неустойчивости. A layer of close-packed particles of a dispersed phase (magnetite) with a protective shell of oleic acid is formed on the interface of a weakly conducting magnetic colloid (magnetic fluid) and water in a perpendicular electric field. The formation of a layer leads to a decrease in the interfacial tension. When the magnetic particles come into contact with the electrode surface, the electrochemical interaction of oleic acid molecules surrounding the particle with water occurs. As a result of the reaction, released ions charge the surface layer. After some time, the particles in the layer get recharged and repelled from the interface. This leads to wave instability. This paper considers the mathematical modeling of instability in the form of a boundary value problem – a dispersion equation. The determining factor in the development of wave instability is the action of the electric field, the formation of the near-electrode layer and, as a consequence, a decrease in the interfacial tension.

The Analysis on the Starting Friction Torque Increase of Magnetic Fluid Revolving Sealing

2013 ◽  
Vol 275-277 ◽  
pp. 429-432 ◽  
Author(s):  
Yu Qiang Cai ◽  
Na Xing
Keyword(s):  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Influence Factor ◽  
Magnetic Field Gradient ◽  
Friction Torque ◽  
Key Factor ◽  
Lower Temperature ◽  
Change Of Microstructure ◽  
Starting Torque ◽  
Main Influence

Abstract. Magnetic fluid revolving sealing is widely used in modern industry. In the process of application, it is founded that the starting friction torque is very large, particularly at lower temperature. This problem has become a key factor restricting the application of magnetic fluid rotation sealing. In this paper, the mechanism of starting torque increase is analyzed, based on the change of microstructure and its viscosity. After analysis , such conclusion is obtained , which can be described: to a certain sealing structure, the type of magnetic fluid, size distribution of magnetic particles as well as the working condition concluding temperature, magnetic field gradient and the revolving velocity of shaft is the main influence factor of starting friction torque . It is very useful to reduce the starting friction torque.

Investigation of Enhancement in Pool Boiling Heat Transfer of a Binary Temperature Sensitive Magnetic Fluid

2013 ◽  
Author(s):  
Giti Karimi-Moghaddam ◽  
Richard D. Gould ◽  
Subhashish Bhattacharya
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Magnetic Fluid ◽  
Boiling Heat Transfer ◽  
Magnetic Particles ◽  
Pool Boiling ◽  
Simulation Software ◽  
Temperature Sensitive ◽  
Magnetic Field Effects ◽  
Pool Boiling Heat Transfer

In this paper, the performance of pool boiling heat transfer using a binary temperature sensitive magnetic fluid in the presence of a non-uniform magnetic field is investigated numerically. By using a binary magnetic fluid, enhanced boiling heat transfer is obtained by thermomagnetic convection without deterioration of properties of the fluid. This work is aimed at gaining a qualitative understanding the magnetic field effects on boiling heat transfer enhancement of magnetic fluids. In order to accomplish this, the boiling process and the effects of position of the external magnetic field on flow pattern and heat transfer are investigated in a 2D rectangular domain using COMSOL Multiphysics simulation software. Finally, the boiling curves for a binary temperature sensitive magnetic fluid and its base fluid (without magnetic particles) are compared for various applied heat flux magnitudes.

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.

Preliminary Research on the Post Treatment of Fluid Magnetic Abrasivetool

2010 ◽  
Vol 455 ◽  
pp. 161-164
Author(s):  
W.D. Li ◽  
Ming Lv ◽  
Sheng Qiang Yang
Keyword(s):  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Post Treatment ◽  
Working Time ◽  
Iron Particles ◽  
Abrasive Particles ◽  
Carrier Liquid ◽  
Preliminary Research

Fluid magnetic abrasivetool(FMA) is one kind of latest finishing abrasivetool which is a sort of suspended fluid composed by magnetic particles, nonmagnetic abrasive particles, surfactants in a non-magnetizable carrier liquid. After a period of working time, the performance-life of the abrasivetool ended because of the cutting- blade of the abrasives particles being passive. While the most costly component- the magnetic particles (carbonyl iron particles) can be reused. This paper has made up two recovery flows to separated carbonyl iron particles from others.

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