EP1632962A1 - Ferromagnetische Teilchen für magnetorheologische oder elektrorheologische Flüssigkeiten, diese Teilchen enthaltende magnetorheologische oder elektrorheologische Flüssigkeiten und zugehörige Herstellungsverfahren - Google Patents

Ferromagnetische Teilchen für magnetorheologische oder elektrorheologische Flüssigkeiten, diese Teilchen enthaltende magnetorheologische oder elektrorheologische Flüssigkeiten und zugehörige Herstellungsverfahren Download PDF

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Publication number
EP1632962A1
EP1632962A1 EP04425669A EP04425669A EP1632962A1 EP 1632962 A1 EP1632962 A1 EP 1632962A1 EP 04425669 A EP04425669 A EP 04425669A EP 04425669 A EP04425669 A EP 04425669A EP 1632962 A1 EP1632962 A1 EP 1632962A1
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EP
European Patent Office
Prior art keywords
ferromagnetic
core
particles
particle according
shell
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04425669A
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English (en)
French (fr)
Inventor
Antonino Veca
Brunetto Martorana
Marco Biasiotto
Anatolii Zvezdin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centro Ricerche Fiat SCpA
Original Assignee
Centro Ricerche Fiat SCpA
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Application filed by Centro Ricerche Fiat SCpA filed Critical Centro Ricerche Fiat SCpA
Priority to EP04425669A priority Critical patent/EP1632962A1/de
Publication of EP1632962A1 publication Critical patent/EP1632962A1/de
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
    • C10M171/001—Electrorheological fluids; smart fluids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/102—Metallic powder coated with organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/44—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids
    • H01F1/447—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C10M2201/04—Elements
    • C10M2201/05—Metals; Alloys
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C10M2201/10—Compounds containing silicon
    • C10M2201/102—Silicates
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2010/00—Metal present as such or in compounds
    • C10N2010/06—Groups 3 or 13
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/055—Particles related characteristics
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/055—Particles related characteristics
    • C10N2020/06—Particles of special shape or size
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/055—Particles related characteristics
    • C10N2020/061—Coated particles
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/185—Magnetic fluids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
    • C10N2050/015—Dispersions of solid lubricants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/33—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials mixtures of metallic and non-metallic particles; metallic particles having oxide skin

Definitions

  • the present invention relates to ferromagnetic particles for magnetoreological or electroreological fluid compositions, of the type including a carrier fluid and ferromagnetic particles dispersed in such fluid.
  • the magnetoreological or electroreological fluid compositions show the essential feature of a variation of apparent viscosity when subjected to a magnetic field or to an electric field. They include ferromagnetic particles, typically with a diameter in the order of a micron, dispersed inside a carrier fluid. In the case of magnetoreological fluids, in the presence of a magnetic field the particles magnetize themselves and orientate their magnetic dipole in parallel to the lines of force of the magnetic field, organizing themselves in particle chains within the fluid. The particle chains act so as to increase the apparent viscosity or overall outflow resistance of the fluid. Without the magnetic field, the particles return in a non organized or free state and the apparent viscosity or outflow resistance of the material is reduced in a corresponding way. The electroreological fluids have a similar behavior and respond to an electric field instead of a magnetic field.
  • Both the electroreological materials and the magnetoreological materials are useful for supplying variable damping forces within such devices as dampers, impact absorption devices and elastomeric supports.
  • magnetoreological or electroreological fluid compositions known so far show, however, a drawback: the ferromagnetic particles dispersed in the carrier fluid essentially consist of pure metals o their alloys, which have by definition molecular weights greater than the carrier fluid and then show a large tendency to settle down, by compromising the behavior features of the general magnetoreological fluid.
  • the problem of the sedimentation may be overcome by performing a mixing of the magnetoreological fluid composition.
  • this operation cannot be easily carried out when the composition is for example within a damper.
  • the shell of the ferromagnetic particle is formed with a ferromagnetic material, while the core is formed of a material having a specific weight lower than the carrier fluid, for example a polymeric material, and shows an empty middle cavity, if necessary.
  • the object of the present invention is to overcome the problem of the sedimentation above disclosed, by providing at the same time a magnetoreological or electroreological fluid further improved with respect to the prior proposal, also from the point of view of an increase of the magnetoreological or electroreological effect, a reduction of the response time of the fluid following to an activation thereof and a greater length of the fluid and the mechanical parts which contact therewith.
  • the invention aims at a ferromagnetic particle for magnetoreological or electroreological fluid compositions including a carrier fluid and ferromagnetic particles dispersed in the carrier fluid, said ferromagnetic particles having a multilayer construction, with a core of a first material, surrounded by a shell of a second material, wherein said first material forming the core is a ferromagnetic material, wherein said second material forming the shell has a specific weight lower than the first material, and wherein the core of ferromagnetic material shows a form anisotropy.
  • the ferromagnetic material core shows an elongated conformation, with a greater size and a lower size.
  • the greater size is substantially equal to an outer size of the particle.
  • the lower size of the ferromagnetic material core of each particle is lower than 1/4 of the greater size, and preferably is lower than 1/8 of such greater size.
  • the ferromagnetic material core may be needle-shaped, or elongated ellipsoid-shaped or be needle-shaped or still simply having the form of an elongated bar.
  • the shell of the particle which can generally be comprised of any material having a specific weight lower than the material forming the core, and preferably also lower than the carrier fluid, is made of a polymeric material.
  • a consequence of the narrow and elongated shape of the metal core is that the volume rate of the particle filled up by the second low specific weight material is greater, with a consequent reduction of the specific weight of the whole particle. This allows to even better contrast the tendency to sedimentation of the particles in the resting fluid.
  • the fact of having the outer shell of the particles made of polymeric material gives rise to further important benefits. In fact, a reduction of the abrasion phenomena of the mechanical parts contacting the fluid occurs, due to the fact that the ferromagnetic material is coated with a polymeric material.
  • the invention is also directed both to the ferromagnetic particles per se, as above defined, and to a magnetoreological or electroreological fluid including such particles.
  • the invention also relates to a method for the production of ferromagnetic particles for magnetoreological or electroreological fluid compositions, which includes the step of forming a plurality of cores of ferromagnetic material having an elongated conformation, with a greater size and a lower size, and the step of forming around each core a shell of a material having a specific weight lower than the material constituting the core.
  • the ferromagnetic material cores may be, for example, carried out by chemical synthesis or through extrusion and/or drawing of a continuous wire and subdivision thereof by following cuts in a plurality of elongated bars.
  • the shell may be carried out around each core through an emulsion polymerization step.
  • Figure 1 shows, by way of example, a preferred embodiment of a ferromagnetic particle according to the invention.
  • the particle generally shown with numeral 1, includes a core 2 of ferromagnetic material, preferably consisting in low coercivity ferromagnetic material (that is, activable with a low magnetic field), such as, for example, iron, cobalt, nickel or their alloys.
  • the ferromagnetic core 2 is acicular or needle-shaped, or elongated ellipsoid-shaped, with a longitudinal axis 2a and a cross section with a circular shape. More generally, the core 2 may have any elongated shape with a greater size L, and a lower size d.
  • the core 2 could be, instead of being elongated ellipsoid- or needle-shaped, elongated bar-shaped with a circular or quadrangular or polygonal section.
  • the lower size d is lesser than 1/4 of the greater size L. Still preferably, the lower size is lesser than 1/8 of the greater size L.
  • the ferromagnetic core 2 is surrounded by a shell 3 consisting in a material having a specific weight lower than the ferromagnetic material forming the core 2.
  • the material forming the shell 3 has a specific weight also lower than the specific weight of the carrier fluid wherein the particles according to the invention are intended to be dispersed.
  • the material forming the shell 3 is a polymeric material. Generally, it can be selected from the group consisting in polymeric foams, microporous polymers, glass, aluminosilicates.
  • the specific weight of the material comprising the shell 3 is preferably lower than 1 g/cm 3 .
  • the shell 3 is obtained in such a way to impart to the particle an overall substantially spherical or slightly ellipsoidal shape.
  • the greater size L of the metal core 2 substantially corresponds with the outer size of the particle 1, in this case therefore with the diameter of the particle 1.
  • the narrow and elongated shape of the metal core 2 permits to obtain different advantages.
  • the total volume rate of the particle 1 filled up by the low specific weight material 3 is high, which allows to reduce to a minimum the tendency of the particles to settle down when they are dispersed in a resting condition fluid.
  • the above described conformation of the core 2 imparts to such core a form anisotropy which renders more effective the dipole-dipole interaction between the particles on the same outer magnetic field applied. This ensures a more rapid alignment of the particles to the lines of force of the magnetic field.
  • Figure 2 of the enclosed drawings shows a plurality of particles 1 dispersed in a fluid in a resting condition, and figure 2 shows the particles in the aligned condition wherein they arrange following to the application of a magnetic field H.
  • the numeral 4 is the fluid wherein the particles 1 are dispersed.
  • the magnetoreological fluid according to the invention therefore shows a reduced response time following to its activation.
  • a further advantage lies in a greater attraction force between the particles with a consequent increase of the magnetoreological effect.
  • the ferromagnetic particles can be obtained by carrying out, at first, the acicular metal cores 2 through chemical synthesis and by carrying out, secondly, the shell 3 by emulsion polymerization.
  • the metal cores 2 are obtained in a form of an elongated bar by means of an extrusion operation and/or continuous wire drawing 20 which is then subdivided through following cuts executed by a cutting tool 21.
  • Figure 6 relates to a further alternative method, wherein a co-extrusion method of the metal and the polymer is carried out by a co-extrusion device 22 which allows to obtain a continuous wire 23 having a metal core coated with a shell of polymeric material, which is then subdivided by a cutting tool 21 in a plurality of short bars 1, forming the ferromagnetic particles according to the invention.
  • each particle has an overall conformation in the form of an elongated bar with a ferromagnetic core.
  • the ferromagnetic particle according to the invention is usable both for carrying out magnetoreological fluids and for carrying out electroreological fluids.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Soft Magnetic Materials (AREA)
EP04425669A 2004-09-07 2004-09-07 Ferromagnetische Teilchen für magnetorheologische oder elektrorheologische Flüssigkeiten, diese Teilchen enthaltende magnetorheologische oder elektrorheologische Flüssigkeiten und zugehörige Herstellungsverfahren Withdrawn EP1632962A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04425669A EP1632962A1 (de) 2004-09-07 2004-09-07 Ferromagnetische Teilchen für magnetorheologische oder elektrorheologische Flüssigkeiten, diese Teilchen enthaltende magnetorheologische oder elektrorheologische Flüssigkeiten und zugehörige Herstellungsverfahren

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Application Number Priority Date Filing Date Title
EP04425669A EP1632962A1 (de) 2004-09-07 2004-09-07 Ferromagnetische Teilchen für magnetorheologische oder elektrorheologische Flüssigkeiten, diese Teilchen enthaltende magnetorheologische oder elektrorheologische Flüssigkeiten und zugehörige Herstellungsverfahren

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EP1632962A1 true EP1632962A1 (de) 2006-03-08

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009105745A1 (en) * 2008-02-22 2009-08-27 Services Petroliers Schlumberger Field-responsive fluids

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH259932A (de) * 1945-12-14 1949-02-15 Stivin Jiri Hochfrequenzkern für Hochfrequenzgeneratoren.
JPS53129158A (en) * 1977-04-18 1978-11-10 Toda Kogyo Corp Needle iron magnetic grain powder manufacturing process
WO1990000583A1 (en) * 1988-07-15 1990-01-25 Reitz Ronald P Induced dipole electroviscous fluids
JPH03219602A (ja) * 1990-01-25 1991-09-27 Toyota Motor Corp 磁粉流体
US5376463A (en) * 1991-03-26 1994-12-27 Hughes Aircraft Company Anisometric metal needles with L-shaped cross-section
DE19654965A1 (de) * 1996-07-26 1998-05-28 Frank Dr Ing Lux Dispergierbare Partikel, die supermagnetische/ferromagnetische Kristalle und/oder maßgeschneiderte di-, tri- oder mehr Blockcopolymere enthalten
US5989447A (en) * 1996-11-28 1999-11-23 G E Bayer Silicones Gmbh & Co. Kg Magnetorheological liquids, a process for producing them and their use, and a process for producing magnetizable particles coated with an organic polymer
US20040105980A1 (en) * 2002-11-25 2004-06-03 Sudarshan Tirumalai S. Multifunctional particulate material, fluid, and composition

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH259932A (de) * 1945-12-14 1949-02-15 Stivin Jiri Hochfrequenzkern für Hochfrequenzgeneratoren.
JPS53129158A (en) * 1977-04-18 1978-11-10 Toda Kogyo Corp Needle iron magnetic grain powder manufacturing process
WO1990000583A1 (en) * 1988-07-15 1990-01-25 Reitz Ronald P Induced dipole electroviscous fluids
JPH03219602A (ja) * 1990-01-25 1991-09-27 Toyota Motor Corp 磁粉流体
US5376463A (en) * 1991-03-26 1994-12-27 Hughes Aircraft Company Anisometric metal needles with L-shaped cross-section
DE19654965A1 (de) * 1996-07-26 1998-05-28 Frank Dr Ing Lux Dispergierbare Partikel, die supermagnetische/ferromagnetische Kristalle und/oder maßgeschneiderte di-, tri- oder mehr Blockcopolymere enthalten
US5989447A (en) * 1996-11-28 1999-11-23 G E Bayer Silicones Gmbh & Co. Kg Magnetorheological liquids, a process for producing them and their use, and a process for producing magnetizable particles coated with an organic polymer
US20040105980A1 (en) * 2002-11-25 2004-06-03 Sudarshan Tirumalai S. Multifunctional particulate material, fluid, and composition

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 197850, Derwent World Patents Index; Class L03, AN 1978-90701A, XP002314542 *
PATENT ABSTRACTS OF JAPAN vol. 015, no. 502 (E - 1147) 18 December 1991 (1991-12-18) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009105745A1 (en) * 2008-02-22 2009-08-27 Services Petroliers Schlumberger Field-responsive fluids
GB2469888A (en) * 2008-02-22 2010-11-03 Schlumberger Holdings Field-responsive fluids
RU2439139C2 (ru) * 2008-02-22 2012-01-10 Шлюмбергер Текнолоджи Б.В. Чувствительные к полю текучие среды
GB2469888B (en) * 2008-02-22 2012-08-22 Schlumberger Holdings Field-responsive fluids
US8506837B2 (en) 2008-02-22 2013-08-13 Schlumberger Technology Corporation Field-responsive fluids

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