Commercial applications of ferrofluids

Raj, K.; Moskowitz, R.

doi:10.1016/0304-8853(90)90058-x

Cited by 545 publications

(235 citation statements)

References 6 publications

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“…These solutions were generated numerically and are in good agreement with the asymptotic results (4.9). This agreement is demonstrated in 15) which is the same as the free-free result (4.10), at leading order.…”

Section: It Cos Try + O(a~4)supporting

confidence: 86%

“…Nonlinear thermal convection in magnetized ferrofluids is a topic of current technical importance since magnetic forces can be used to create circulation of coolant in small passages where natural convection is either absent or ineffective. Examples of current uses include the cooling of electrical equipment such as loudspeakers as well as many uses as dynamic process and exclusion seals [15]. [2] Strongly nonlinear vortices in magnetized ferrofluids 147…”

Section: Introductionmentioning

confidence: 99%

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Strongly nonlinear vortices in magnetized ferrofluids

Russell

Blennerhassett

Stiles

1998

J. Aust. Math. Soc. Series B, Appl. Math

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Nonlinear convective roll cells that develop in thin layers of magnetized ferrofluids heated from above are examined in the limit as the wavenumber of the cells becomes large. Weakly nonlinear solutions of the governing equations are extended to solutions that are valid at larger distances above the curves of marginal stability. In this region, a vortex flow develops where the fundamental vortex terms and the correction to the mean are determined simultaneously rather than sequentially. The solution is further extended into the nonlinear region of parameter space where the flow has a core-boundary layer structure characterized by a simple solution in the core and a boundary layer containing all the harmonics of the vortex motion. Numerical solutions of the boundary layer equations are presented and it is shown that the heat transfer across the layer is significantly greater than in the conduction state.

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Section: It Cos Try + O(a~4)supporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Strongly nonlinear vortices in magnetized ferrofluids

Russell

Blennerhassett

Stiles

1998

J. Aust. Math. Soc. Series B, Appl. Math

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“…Metal oxide nanocrystals are widely applied in catalysis, energy storage, magnetic data storage, sensors, and ferrofluids [1][2][3][4]. Tetramanganese oxides (Mn 3 O 4 ) are particularly used as main sources of ferrite materials [5] and applied in numerous industrial fields such as magnetic [6], electrochemical [7], and catalysis [8,9].…”

Section: Introductionmentioning

confidence: 99%

Mn3O4 Nanoparticles: Synthesis, Characterization, and Dielectric Properties

Dhaouadi¹,

Ghodbane²,

Hosni

et al. 2012

ISRN Spectroscopy

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Mn 3 O 4 nanoparticles were prepared by a simple chemical route using cetyltetramethylammonium bromide (CTAB) as a template agent. Mn 3 O 4 nanocrystals present an octahedral shape, and their crystallite size varies between 20 and 80 nm. They were characterized by XRD, SEM, DTA/TG, and IR spectroscopy. XRD studies confirm the presence of a highly crystalline Mn 3 O 4 phase. The Rietveld refinement of the X-ray diffraction data confirms that Mn 3 O 4 nanoparticles crystallize in the tetragonal system with space group I41/amd. DTA/TG and XRD measurements demonstrate the phase transition toward a spinel structure between 25 and 700 • C. The electrical conductivity increases between 80 and 300 • C, suggesting a semiconducting behaviour of Mn 3 O 4 . Both dielectric dispersion (ε ) and dielectric loss (ε ) were investigated from 80 and 300 • C in the frequency range of 10 Hz-13 MHz. The dielectric properties showed typical dielectric dispersion based on the Maxwell-Wagner model.

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“…Surfactant adsorption on nanoparticles is an important issue, since it not only affects the colloidal stability but also the optical [8] and magnetic properties [9][10][11]. The magnetic properties of magnetite are at the basis of several ferrofluidic [12] and biomedical applications [13], including contrast enhancement of magnetic resonance imaging (MRI). Here, we use in situ FTIR spectroscopy to analyze the surface of magnetite nanoparticles that are dispersed in solutions of oleic acid and oleylamine in cyclohexane.…”

Section: Introductionmentioning

confidence: 99%

Surface analysis of magnetite nanoparticles in cyclohexane solutions of oleic acid and oleylamine

Klokkenburg

Hilhorst

Erné

2007

Vibrational Spectroscopy

140

106

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The surface of magnetite (Fe 3 O 4 , d ¼ 6:3 AE 0:7 nm) nanoparticles dispersed in cyclohexane was studied in the presence of oleic acid and oleylamine using in situ FTIR spectroscopy. Equimolar mixtures of these surfactants are widely used in the chemical synthesis of nanoparticles with a low polydispersity. Here, the IR spectra indicate that oleic acid molecules adsorb to the magnetite surface as a carboxylate. Measurements as a function of surfactant concentration yield an adsorption isotherm, with about two surfactant molecules adsorbed per nm 2 of magnetite at 1 mM surfactant concentration and about 3.5 molecules per nm 2 at 310 mM, of the order expected for full monolayer coverage. No spectral indication is found of oleylamine molecules at the surface of magnetite. In solution, however, almost every oleylamine molecule combines with an oleic acid molecule to form an acid-base complex, with an association constant of 3:5 Â 10 4 dm 3 mol À1 .

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Commercial applications of ferrofluids

Cited by 545 publications

References 6 publications

Strongly nonlinear vortices in magnetized ferrofluids

Strongly nonlinear vortices in magnetized ferrofluids

Mn3O4 Nanoparticles: Synthesis, Characterization, and Dielectric Properties

Surface analysis of magnetite nanoparticles in cyclohexane solutions of oleic acid and oleylamine

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