Redistribution of ferromagnetic particle concentration in a magnetic fluid

A mathematical model for the diffusion process of ferromagnetic particles in a magnetic fluid is described. The unique solvability of the steady‐state particle concentration problem is investigated and an analytical expression for its solution is found. In case that the fluid is under the action of a high‐gradient magnetic field a Stefan‐type diffusion problem can arise. An algorithm for solving the Stefan‐type steady‐state problem is developed.

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Diffusion microrheology of ferrofluids

Revista Mexicana de Física ◽

10.31349/revmexfis.64.82 ◽

2018 ◽

Vol 64 (1) ◽

pp. 82 ◽

Cited By ~ 4

Author(s):

R. Peredo-Ortíz ◽

M. Hernández-Contreras

Keyword(s):

Statistical Mechanics ◽

Computer Simulations ◽

Magnetic Fluid ◽

Structure Factor ◽

Diffusion Coefficients ◽

Magnetic Particles ◽

Particle Concentration ◽

Thermal Fluctuations ◽

Self Diffusion ◽

Viscous Modulus

We provide a statistical mechanics approach to study the linear microrheology of thermally equilibrated and homogeneous ferrofluids. Theexpressions for the elastic and loss moduli depend on the bulk microstructure of the magnetic fluid determined by the structure factor of thesuspension of magnetic particles. The comparison of the predicted microrheology with computer simulations confirms that as a function ofrelaxation frequency of thermal fluctuations of the particle concentration both theory and simulations have the same trends. At very shortfrequencies the viscous modulus relates to the translational and rotational self-diffusion coefficients of a ferro-particle.

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Measurement of ferromagnetic particle concentration for characterization of fluidized bed fluid-dynamics

Powder Technology ◽

10.1016/j.powtec.2013.01.040 ◽

2013 ◽

Vol 239 ◽

pp. 147-154 ◽

Cited By ~ 10

Author(s):

Diana Carolina Guío-Pérez ◽

Tobias Pröll ◽

Hermann Hofbauer

Keyword(s):

Fluid Dynamics ◽

Fluidized Bed ◽

Particle Concentration ◽

Ferromagnetic Particle

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Effect of Particle Concentration on Lubricating Properties of Magnetic Fluid

Journal of Nanofluids ◽

10.1166/jon.2018.1472 ◽

2018 ◽

Vol 7 (3) ◽

pp. 420-427 ◽

Cited By ~ 1

Author(s):

Kinjal Trivedi ◽

Anjana Kothari ◽

Kinnari Parekh ◽

Ramesh V. Upadhyay

Keyword(s):

Magnetic Fluid ◽

Particle Concentration ◽

Lubricating Properties

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A magnetic super lattice

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126597 ◽

1987 ◽

Vol 45 ◽

pp. 360-361 ◽

Cited By ~ 1

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.

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