cimtec08 vekas final a

8/11/2019 CIMTEC08 Vekas Final A

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CIMTEC 2008

Ferrofluids

andMagnetorheological Fluids

Ladislau Vks

Laboratory of Magnetic Fluids

Center for Fundamental and Advanced Technical ResearchRomanian Academy-Timisoara Branch, Timisoara, Romania

and

National Center for Engineering of Systems with Complex Fluids

University Politehnica of Timisoara, Timisoara, Romania


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CIMTEC 2008

OUTLINE

Short history of the field

Magnetically controllable fluids

Magnetic nanoparticles and ferrofluids, application orientated synthesis

Colloidal stability and structural processes

Magnetic and flow properties

Magnetorheological fluids, main types and composition

Structural processes and magnetorheological behavior

New type of composite materials


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CIMTEC 2008

FLUIDITY + MAGNETIC PROPERTIES = ??

New kind of materials, new phenomena

The beginning

Magnetorheological fluid National Bureau of Standards Technical News Bulletin 1948;32(4):54-60.

J. Rabinow Proceedings of the AIEE Trans., 1948. 67. p. 1308-1315.

Ferrofluid/Magnetic fluid T.L. OConnor, Belgian Patent 613,716 (1962)

S. Papell (NASA), US Patent 3,215,572 (1965)


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CIMTEC 2008

Magnetically controllable fluids

Ferrofluids, magnetic (nano)fluids

Ultrastable colloidal suspensions of magnetic nanoparticles (MNPs) in acarrier liquid (CL)- no sedimentation Quasihomogeneous magnetizable liquids

Approximatively Langevin type magnetic behavior and Newtonian flowproperties, small magnetoviscous effect

Magnetorheological fluids Suspensions of micron-sized ferromagnetic particles in a carrier liquid-

significant sedimentation rate

Non-Newtonian behavior, strongly magnetic field dependent yield stress andeffective viscosity (about 100-1000 times increase)

Magnetizable gels&elastomers Nano- or micro-meter range magnetic particles dispersed in a polymer matrix

Field dependent size and mechanical properties, tunable elastic properties


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CIMTEC 2008

Synthesis procedures

I. Synthesis of magnetic nanoparticles

Chemical co-precipitation

Thermal decomposition of organo-metallic compounds

II. Stabilization/dispersion in non-polar or polar carrierliquids

Electrostatic stabilization (water)

Steric or electro-steric stabilization (organic carriers and water)


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CIMTEC 2008

Composition & mechanism of sterical stabilization

Composition: MNP - magnetite, maghemite, cobalt-ferrite, iron, cobalt; CL- non-polar and polarorganic solvents, water; S - carboxylic or sulphonic acids, polymers

Sterical stabilization: MNPs dispersed in a CL are coated with mono- or double-layer of organic

surfactant (S) molecules in order to prevent their agglomeration due to magnetic dipole-dipole andvan der Waals interactions

Entropic repulsion betweensurfacted MNPs

- distance between particles

Nuclear and magnetic particle structures in FFs2R1- surfacted particle size, incl. surfactant layer s2R particle size; 2 Rm- magnetic size

Nuclear structure Sterical stabilization

Solvent (CL)

Surfactant layer

Magnetic structure


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CIMTEC 2008

Colloidal stability

S. Odenbach, Ferrofluids, 2006M. Klokkenburg et al., JoPhys CM, 2008

Stabilization procedures prevent gravitational settling of MNPs,agglomerate formation by magnetic and van der Waals interactions

Non-dimensional dipolar

interaction energy

Tk

dM

b

md

=72

32

0int

int > 1

Unstable FF, agglomerate formation

dTEM = 9.0 nm

int = 0.5

Cryo-TEM: FF/Decalin (OA)

200 nm

int < 1

Stable FF, no agglomerates

dTEM = 18.6 nmint = 4.4

Cryo-TEM: FF/Decalin (OA)500 nm


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CIMTEC 2008

Synthesis procedures (1)Organic non-polar carrier liquids - monolayer surfactant coated MNPsAqueous

solutionsCoprecipitation

NH4OH

(solution 25%)

Fe3+, Fe2+

Subdomain Fe3O4

nanoparticles

Surfactant (pure

oleic acid 96%)Sterical stabilisation

(chemisorption)

353 K

Phase separation

Magnetic

decantation

Aqueous solution of

residual salts

Monolayer coveredmagnetic particles

Distilled water

t = 70 - 80oCRepeated washing

Magnetic decantation Aqueous solutionresidual salts

Surfactants: oleic acid (OA), stearic acid (SA), palmitic acid (PA), myristic acid (MA), lauric acid (LA)Carriers : hydrocarbons (H), deuterated hydrocarbons(D-H), halogenated compounds(Hal)

80-82 C

Lab. Magnetic Fluids Timisoara

MF/H/OA: D. Bica, R.Minea, Patent RO 97556(1989); D. Bica, Rom. Rep. Phys. 47(1995)MF/H/LA; MA : L. Vekas et al. Rom. Rep. Phys. 58(2006); M.V. Avdeev, D. Bica et al. JMMM, 311 (2007)

Monolayer covered magneticnanoparticles + free oleic acid

Acetone Extraction

Magnetic decantation Acetone, water,

free oleic acid

Stabilised magneticnanoparticles

HydrocarbonDispersion

Primary monolayer stabilisedmagnetic fluid on light

hydrocarbon carrier

Magnetic decantation /filtration

Repeated flocculation /redispersion of surfacted

nanoparticles

Free oleic acid

NONPOLAR PURIFIED MAGNETIC FLUID


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CIMTEC 2008

Synthesis procedures (2)Organic polar carrier liquids - double layer surfactant coated MNPs

D. Bica et al. Patents RO 93107 (1987), 93162 (1987), 97224 (1989),97599(1989), 105048 (1992),

115533 (2000); D. Bica, Rom. Rep. Phys. 47(1995)

D. Bica, L. Vekas, M. Rasa, J.Magn.Magn.Mater. 252 (2002)

DBS-dodecyl-benzen-sulphonic acid

PIBSA-poly-izobutylen-succin-anhydrideLab. Magnetic Fluids Timisoara

Acetone Flocculation

Magnetic decantation Acetone +

hydrocarbon

Monolayer stabilisedmagnetic nanoparticles

DBS or PIBSA

(C8)

- Secondary stabilisation

(physical adsorbtion)

- Dispersion

Alcohols C3-C10/HVO/

Diesters(DOA/DOS)

MF/HIGH

VACUUM OIL

MF/ALCOHOLS

(Polialcohols)

MF/DIESTERS

(DOA, DOS)

VEGETAL

OILS

- Coprecipitation Fe2+, Fe3+, NH4OH sol. 25%- Sterical stabilisation, (chemisorbtion, oleic

acid 96%)- Phase separation- Repeated washing- Dispersion

Primary magnetic fluid onlight hydrocarbon carrier

- Magnetic decantation- Filtration- Repeated flocculation /

redispersion of surfactednanoparticles

Free oleic acid

Nonpolar purified magnetic

fluid

FF/organic polar carrierOA+DBS,OA + PIBSA,OA + PIBSIdouble layer

sterical stabilization

MNP


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CIMTEC 2008

Magnetic decantation

Fe3O4 nanoparticles

Repeated washing

Fe3O4 nanoparticles

Chemisorbtion

Phase separation

Coprecipitation, pH=11Fe3+, Fe2 solution NaOH6N solution

or NH4OH80C

Distilled water

70-80C

Lauric acid (LA)(or MA/PA/OA)

Residual salt solution

Residual salt solutionMagnetic decantation

80C


Dispersion

Primary magnetic fluid


Magnetic organosol, pH= 8. 5 9.0

Residual salt solution

NaOH

Water

MF/Water (LA+LA /MA+MA/PA+PA/

OA+OA)

Uncoated magnetite

nanoparticles, agglomerates

Synthesis procedure (3)

Biocompatible FFs

FF/waterLA+LA, MA+MA,

OA+OA, LA+DBS,MA+DBS, OA+DBS

double layersterical stabilization

D.Bica, Patent RO 90078 (1985); Rom. Rep. Phys.,47(1995)

D. Bica. L. Vks, M. Rasa, J. Magn. Magn. Mater.,252(2002)

D.Bica, L. Vekas, M.V.Avdeev, O. Marinica, V. Socoliuc,

M. Balasoiu, V.M.Garamus, J.Magn. Magn. Mater. 311(2007)

MNP

Water (highly polar) carrier- double layersurfactant coated MNPs


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CIMTEC 2008

Generalized synthesis procedure of monodisperse Fe nanoparticlesSize-selective process: varying the molar ratio Fe- carbonyl /OA andthe steric bulkiness of surfactants used

Thermal decomposition of iron pentacarbonyl in the presence of oleic acid at 100 C

The iron oleate complex was prepared by reacting Fe(CO)5 and oleic acid at 100 C Iron nanoparticles were then generated by aging the iron complex at 300 C

TEM images of iron nanoparticles:(a) three-dimensional array of 7nm

Fe nanoparticles and

(b) 11 nm Fe nanoparticles

Liquid phase synthesis of iron NPs by thermaldecomposition

T. Hyeon, Chem.Comm., 2003

20 nm


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CIMTEC 2008

- Synthesis procedure for monodisperse -Fe2O3 nanoparticles -

Maghemite nanoparticles with sizes of 7 and 11 nm synthesized by using reaction mixtures with

[Fe-(CO)5]:[oleic acid] molar ratios of 1:2 and 1:3, respectively.

Dominating size controlling factor: the molar ratio of iron pentacarbonyl /oleic acid.

Liquid phase synthesis of iron oxide NPsby thermal decomposition

Monodisperse iron nanoparticles monodisperse -Fe2O3 nanocrystals

Controlled oxidation using trimethylamine N-oxide ((CH3)3NO)- mild oxidant

T. Hyeon, Chem.Comm. 2003


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CIMTEC 2008

S. Behrens et al Z. Phys. Chem. 2006S. Behrens et al., J Phys: Condens. Matter, 2006

a. TEM image displaying several Co nanoparticles

b. HRTEM image of a single Co nanoparticleshowing the polycrystalline structure.

High magnetization FFs with Co nanoparticles

Liquid phase synthesis of Co NPs by thermal decomposition of Co2(CO)8

Co2(CO)

8+ Al-R

3

toluen (80-900C)

heating (1100C;18 h) under stirring

cooling to room temperature

smooth oxidation (synthetic air)

black precipitate Co(O) with oxidized protecting shell

stabilization of Co NPs (Korantin SH or oleic acid+Oleyl

amine) in hydrocarbon carrier

high magnetization FF (1000-1700 G)

2 nm

Axial magnetohydrostatic bearing

a) Stator b) Section enlargement of the stator withthe ferrofluid c) General view of the bearing

10 nm


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CIMTEC 2008

Experimental setupfor the laser pyrolysis of

iron/iron oxide nanoparticles+system for powder collection in

the toluene bubbler

Focused CW CO2 laser radiation (l = 10.6 mm,output power 35 W) orthogonal to the reactant gas stream

Reactive mixture: Fe(CO)5 vapors + C2H4 gas carrier. Synthesis parameters: 3000 Pa for the reactor pressure and100 sccm for the ethylene flow (bubbling through the

liquid carbonyl reservoir at temperature of 25 0C)

E. Popovici et al., Appl.Surf.Sci. 2007

Gas phase synthesis of iron/iron oxid NPs bylaser pyrolisis

TEM/HRTEM:iron/iron oxide coreshell MNPsenhanced magnification TEM : encapsulated featureof the nano-Fe powder - higher inset; HRTEM: single

nanoparticle - lower inset


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CIMTEC 2008

a) XRD diagram: well defined Fepeaks mixed with Fe2O3 and Fe3O4

b) TEM image: hydrocarbon-based FFrevealing almost single particles orassemblies of a few nanoparticles

E. Popovici et al., Appl. Surf. Sci. 2007

Laser pyrolisis synthesized iron/iron oxide MNPsdispersed in hydrocarbon carrier

a)

b)

Iron/iron oxide core-shell MNPs

Sterical stabilization - oleic acid (OA) (heating up to 353 K;pH 8.5; continuous stirring; chemisorption of OA

Monolayer coated MNPs

Elimination of free OA - magnetic decantation

Stabilized MNPs

Addition of carrier - hydrocarbon, e.g. petroleum

Heating up to 110120 8C - elimination of water + acetone

Primary hydrocarbon-based ferrofluid

Magnetic decantation; repeated flocculation/re-dispersion of MNPs(elimination of free oleic acid)

Sterically stabilized, highly purified FF with surface protected MNPs


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CIMTEC 2008

Application orientated evaluation of ferrofluidsManifold characterization

Size distribution of magnetic nanoparticles: TEM, HRTEM

Composition and magnetic field dependent structural processes, sterical stabilization and

long-term colloidal stability: SANS, SANSPOL (B = 0-2.5 T)

Mechanism of stabilization and chemical size selection of dispersed magnetic particles

Dilution stability and phase transition phenomena: magneto-optical investigations, DLS

Magnetic properties vs. concentration: VSM measurements

Flow properties under the influence of applied magnetic field: MR investigations

Evaluation and selection of FFs for various applications

FFs for rotating seals, bearings high magnetization

organic carrier liquids

excellent stability in intens and stronglynon-uniform magnetic fields

FFs for biomedical applications

biocompatibile components

usually water carrier

stability in physiological conditions


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CIMTEC 2008

Sterical stabilization: efficiency of differentchain length surfactants

R. Tadmor, R. E. Rosensweig, J. Frey, J. Klein,

Resolving the Puzzle of Ferrofluid Dispersants, Langmuir16 (2000)

Unsaturated mono-carboxylic acid

palmitic acid (PA)

C16H32O2stearic acid (SA)

C18H36O2

oleic acid (OA)C18H34O2

Excellent stabilizerdue to high solvation!

Non-efficient

stabilizers

because of

worse solvation?short chain?

myristic acid (MA)

C14H32O2

lauric acid (LA)

C12H32O2

Non-efficient stabilizer

because of worse solvation

doublebond kink

Saturated mono-carboxylic acids


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CIMTEC 2008

Schematic view of SANS experiment on system of magnetic

nanoparticles. In case of unmagnetized system scattering

pattern is isotropic over radial angle on detector plane

Schematic view of SANSPOL experiment on system of

magnetic nanoparticles. Anisotropy in the scattering pattern

over radial angle is caused by magnetization of the system

Small Angle Neutron Scattering investigationsStructural processes in ferrofluids

FFs in zero field (B=0) conditions FFs under the influence of applied

magnetic field (B>0)

1-100 nm range

GKSS Geesthacht BNC KFKI Budapest JINR Dubna


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CIMTEC 2008

Small Angle Neutron Scattering investigationsSANS Interparticle interaction

magnetite/oleic acid/H-benzene

Type of structure-factor: long-range attraction withshort-range (contact) repulsion

JINR Dubna, BNC Budapestline: model of polydisperse

core-shell particles

)()(~ 2 qSqF NN

0,1 1

0,01

0,1

1

10

100

m = 0.15m = 0.075m = 0.038m = 0.019m = 0.01

I(q),cm-1

q, nm-1

Cluster fractal dimension D ~ 1,5 2.5Mean radius of cluster units R ~ 10 nm

magnetite/water: OA+DBS, DBS+DBS, OA+OA

Highly stable ferrofluids Weakly stable ferrofluids

M.V. Avdeev, V.L Aksenov, M. Balasoiu et al. J. Coll. Interface Sci, 2006L. Vekas, M.V. Avdeev, D. Bica, Magnetic fluids: Synthesis and Structure (Springer V, to appear)


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CIMTEC 2008

Small Angle Polarized Neutron Scattering investigationsSANSPOL High magnetic field stability test

Highly stable magnetic nanofluid, maximal m~10 %.

Investigation at B= 2.5 T d-cyclohexane + Fe3O4 + MA , m= 2.8 %

0.1 1

0.1

1

10

I(q),cm

-1

q, nm-1

I

I+

0.1 1

1E-3

0.01

0.1

1

10

F2

N

F2

M

Rg=3.7 nm

Rg=4 nm

I(q),cm-1

q, nm-1

Averaged (over radial angle ) intensities of the scattering

for two spin orientations of polarized neutrons

Blue solid line fit of the core-shell model.Final parameters are

R0=2.3 nm; S=0.28; =1.35 nm.

Dashed lines are Guinier approximations.SANSPOL tests-GKSS Geesthacht-V. Garamus, M.V. Avdeev


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CIMTEC 2008

SANS and VSM analyses

Samples stabilized with different chain length carboxylic acids

Magnetization curves (points) for ferrofluids/ DHN, m = 1.5 %.Lines are the results of the polydisperse Langevin approximation.

SANS curves (points) FFs in DHN normalized to m= 1.5 %.Lines are the results of approximation by the model of polydisperse

independent spheres

Inset : particle sizedistributions of magnetite

(atomic size)

Inset : particle sizedistributions of magnetite(magnetic size)

SANS

0.1 11E-4

1E-3

0.01

0.1

1

10

100

SA, PA, MA, LA

q, nm-1

I(q),cm-1

OA

0 1 2 3 4 5 6 7 8

DN

(R)

R, nm

OA

SA, PA, MA, LA

VSM

0 500 10000.0

0.2

0.4

0.6

0.8

1.0

SA, PA, MA, LA

OA

LA, MA, PA,

SA

OA

M/M

s

H, kA/m

0 1 2 3 4 5 6 7 8

DN

(R)

R, nm

Lab. Magnetic Fluids Timisoara GKSS Geesthacht BNC Budapest

M.V. Avdeev, D. Bica, L. Vekas,V.L. Aksenov, A.V. Feoktystov,

L. Rosta, V.M. Garamus,

R. Willumeit JMMM 2008


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CIMTEC 2008

SANS curves and resulting size distributions

Mixed surfactants monolayer (MA + OA) with 1:0, 1:1 and 0:1 mixing ratios

FFs with chemically tailored magnetic nanoparticlesSize selective synthesis-stabilization of magnetic nanoparticles

with mono-layer of mixed surfactants

Non-polar carrier (D-benzen), =1.1 %

Increased MA content, more reduced diameter and standard deviation M.V. Avdeev, D. Bica et al. (MISM, 2008)

Resulting log-normal size-distribution functions

0 1 2 3 4 5 6 7 8

OA/MA 1/1

DN(R)

R, nm

MA (Dm=5.15 nm; = 1.26)

(Dm=6.24 nm; = 1.79)

OA (Dm=7.34 nm; = 2.98)

Nuclear scattering contribution. Solid lines are fits of

the core-shell model

0.1 1

I(q),cm

-1

q, nm-1

OAOA/MA 1/1

MA


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CIMTEC 2008

Flow properties under the infuence of appliedmagnetic fieldNon-polar carrier, mono-layer sterical stabilization with MA (C14) and OA (C18)

Concentrated (Ms= 61 kA/m)

OA stabilized MF/Utr sampleMR effect ~20-30%

Concentrated (Ms= 62 kA/m)

MA stabilized FF/Utr sampleMR effect 10%

Coil

Magnetic Field

Highly Permeable Material

Parallel Plate

non-magnetic

Magnetic Fluid

MR cell MCR 300

Well stabilized FFs have veryreduced MR effect

L.Vekas, D. Bica et al. Rom. Rep. Phys. 2006


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CIMTEC 2008

Colloidal stability of water based ferrofluidsDynamical Light Scattering investigations-NanoZSDouble layer sterical stabilization using different chain length surfactants

Biocompatible ferrofluids

-4.5

-3

-1.5

0

1.5

3

4.5

2 3 4 5 6 7 8 9 10pH

Electrophoreticmobility(

cmV

-1s-1)

Cationic particles

Anionic particles

OA+OA

LA+LA

MA+MA

Magnetite

Double la yer coated magne tite0

10 0

20 0

30 0

40 0

50 0

60 0

70 0

80 0

2 3 4 5 6 7 8 9 10pH

Magnetite 0.001 MLA +LA 0.001 MLA +LA 0.01 MMA+MA 0.01 MMA+MA 0.1 MOA+OA 0.001 MOA+OA 0.01 M

Aggregation

Dilute ma gnetic fluids

Averagehydrodyn

amicsize(nm)

Aggregation of magnetite particles in 0.001,

0.01 and 0.1 M NaCl solutions at 25+0.10C.

E. Tombcz, D. Bica et al, JoPhys CM 2008

Effect of anionic surfactant double layer coating

on the pH-dependent charge state

OA+OA and MA+MA stabilized FF/water samples keep theircolloidal stability in the physiological range of pH (6-8)


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CIMTEC 2008

Restoring force Frinduced by

magnetic field H

in shearing flow

No field: H=0Fe particles diffusing

randomly; blades

moving freely

Increasing field: H > 0Fe particles start forming

chains; resistance between

blades increases

Saturating field: H HsatStrong field forms continuous

chains-quasi-solid state;blades movement restricted

Composition & intense structuring mechanismMagnetic particles: magnetically soft multi-domain Fe, Fe alloys of 1-10 mCarrier liquids: petroleum based oils, silicon oils, mineral oils, synthetic oils, waterSuspension agents: thixotropic and surface active agents (e.g., carboxylic acids,

stearats, polymers, organoclays)

Field dependent magnetic moment of particles m= 40fa3H

0; =(p -f)/(p+2f)

Field dependent magnetic coupling parameterint

MR = 0fa3H

02/(2kT)

int

MR = 1 for H0=127 A/m; 2a=1m

intMR ~ 108 1 for usual H values

Strongly non - Newtonian behaviorYield stress: 50-100 kPaLarge MR effect: 102 103 timesincrease of effective viscosity


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CIMTEC 2008

Main characteristics MR effect ~ 102 - 103

Yield stress 50-100 kPa

Max. applied field 150-250 kA/m

Density 3-4 g/cm3

Response time < 1 ms

Off-state viscosity 0.10 - 1.0 Pa.s (at 25 0C)

Operational temp - 400C to + 1500C

Magnetic particles Fe (~ 3m), magnetically soft

No hysterezis

Main problems to be solved Gravitational settling

Difficult redispersing of sediment

Further increasing the yield stress / MR effect

Possible solutions Non-magnetic nanofillers

Non-spherical shaped magnetic particles

Extremely bidisperse MR suspensions

Magnetorheological fluids

G. Bossis, O. Volkova, S. Lacis, A. Meunier, in:S. Odenbach (Ed) Ferrofluids.Magnetically controllable fluids and their applications(Springer-Verlag 2002)

J. D. Carlson, M. R. Jolly, Mechatronics(2000)

F. D. Goncalves, J.-H. Koo, M. Ahmadian,The Shock and Vibration Digest(2006)


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CIMTEC 2008

MRFs with magnetic fibers Lopez-Lopez, Vertelov, Bossis, Kuzhir, Duran, J. Mater. Chem., 2007

Dynamic yield stress, as a function ofthe external magnetic field strength

Cobalt suspensions in silicone oil (solid

concentration 5 vol%). Cobalt spheres, 1.3 m

Cobalt wires

Co wires

Co spheres

Extremely bidisperse MRFs Viota, Gonzalez-Caballero, Duran, Delgado, J. Coll.Int. Sci., 2007

Three-times increase of yield stress

Role of magnetic particle shape & size

Photographs of bidisperse MR suspensions after 24 h sedimentation. the arrows indicate the sediment height.

in all cases, micron size particle concentration m= 10%;

nanoparticle concentrations nare, from left to right (in %),0, 1, 2, 3, 5, 7.

Nano-micro MRFComposition

Spherical particles

Decrease ofsedimentation rate

Halo structure formation

Cloud of magnetic nanoparticlesaround micron sizedparticles, large size aggregates

Micro-Magnetite 1450 nm Nano-Magnetite 8 nm Carrier: water

SEM image of Co wiresLength 30-60m; Width 4-5 m

10m


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CIMTEC 2008

1

00 1

*

1 tanh tanh

1

n

m

= + +

+

& & & &

& & &&

&

Shear stress vs. shear rate curves forB = 0,..., 502 mT MRF-140CG; micro 0.40

Commercial sample Lord Co(~mFe)

Shear stress vs. shear rate curves forB = 0,..., 502 mT D1; total 0.40

micro 0.2; nano 0.2

Nano-micro MRF lab sample

1

0 0 11 tanh tanh

n

= + +

& & &&

& & &

Fit: Herschel-Bulkley (H-B) type behavior for B>0 Fit: Cross+ H-B formula for B>0

Fit: Carreau-YasudaFormula for B=0

MR effect

Nano-micro MRF


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CIMTEC 2008

)()0(/)]0()([ BfB =

Effect of nanosized magnetic particles on MR effectmicro 0.2; nano 0.2

D. Resiga, D. Bica, L. Vks, ERMR 2008, Dresden

MRF-140CG comercial sample

D1 lab sample

MR effect

Nano-micro MRF


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CIMTEC 2008

Composite with field induced uniaxial ordered structure

New generation of magnetic elastomers - new type of magnetic compositesNano- and/or micron-sized magnetic particles dispersed in a high elastic polymeric matrix-Poly(dimethyl siloxane (PDMS)

Schematic picture ofthe bending of themagnetic PVA gels

under compression.

Anisotropic mechanical (a)and swelling [(b) and (c)]behaviour as seen by the naked eye.

The arrow indicates the direction of themagnetic field during the preparation.

Preparation of uniaxially ordered composite deformation ratio

Smart composites with controlled anisotropy, POLYMER, 2006, Zs. Varga, G. Filipcsei, M. Zrnyi*HAS-BUTE Laboratory of Soft Matters, Dept Physical Chemistry, Budapest


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CIMTEC 2008

Intelligent polymeric nanocomposite membrane

Schematic representation of channels made of MPS-PNIPA latex built in the PVA gel matrix:

(a) off state below the collapse transition temperature;

(b) on state above the collapse transition temperature.

Response to external stimuli-regulation of drug permeation and release- biomedical applications

Ordered nanochannels can act as on-offswitches or permeability valves

Poly(Nisopropyacrylamide)gel ---- PNIPA gel Magnetic polystyrenelatex --- MPS

Macromolecules 2006, 39, 1939-1942 I.Csetneki, G.Filipcsei, M. Zrnyi* HAS-BUTE Laboratory of Soft Matters, Budapest

Arrows indicate the

diffusive mass transferin the channels of PVAmembrane


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CIMTEC 2008

CONCLUSIONS

Properties of magnetically controllable fluids are tailored

mainly by varying the size range of magnetic particles 100104 nm

Saturation magnetization is determined by the volume fraction

and magnetic properties of the solid component 10 7x103 G

Non-dimensional particle interaction energy int covers a wide range 0.5 ... 108

Magnetorheological effect / 10-1 103

OUTLOOK

Increasing trend of applicationsof

magnetically controllable fluidsin

biology and medicine


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CIMTEC 2008

Acknowledgements

Dr. Doina BICA Laboratory of Magnetic Fluids-CFATR TimisoaraRomanian Academy-Timisoara Division

Dr. Mikhail AVDEEV- JINR-Dubna, Russia

Prof. Mikls ZRINYI - Dept.Physical Chemistry, Budapest Technical University, Hungary

Dr. Ion MORJAN - INFLPR Bucuresti, Romania

Prof. Etelka TOMBCZ - Dept. Colloid Chemistry-Univ. Szeged, Hungary

Ass.Prof. Dr. Daniela Susan-Resiga- West University Timisoara, Romania

Dr. Rodica TURCU - INCDTIM Cluj-Napoca, Romania

Dr. Adelina HAN - CNISFC- Univ. Politehnica Timisoara, Romania

National Authority for Scientific Research (Romania):CEEX Research projects FeMANANOF, NanoMagneFluidSeal


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CIMTEC 2008

Thank you for attention!

Lab. Vant Hoff of Colloids - 100 years anniversary

Exhibition at Univ. Utrecht 2004 - A.P. Philipse (Utrecht), Doina Bica (Timisoara)

Dynamicalsurface

instabilities

cimtec08 vekas final a

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