WO1997048109A1 - Organomolybdenum-containing magnetorheological fluid - Google Patents

Organomolybdenum-containing magnetorheological fluid Download PDF

Info

Publication number
WO1997048109A1
WO1997048109A1 PCT/US1997/009761 US9709761W WO9748109A1 WO 1997048109 A1 WO1997048109 A1 WO 1997048109A1 US 9709761 W US9709761 W US 9709761W WO 9748109 A1 WO9748109 A1 WO 9748109A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnetorheological fluid
organomolybdenum
fluid according
oil
group
Prior art date
Application number
PCT/US1997/009761
Other languages
French (fr)
Inventor
Beth C. Munoz
Anthony J. Margida
Thomas J. Karol
Original Assignee
Lord Corporation
R.T. Vanderbilt Company, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Lord Corporation, R.T. Vanderbilt Company, Inc. filed Critical Lord Corporation
Priority to EP97928864A priority Critical patent/EP0904591B1/en
Priority to DE69737625T priority patent/DE69737625T2/en
Priority to JP50169098A priority patent/JP3893449B2/en
Publication of WO1997048109A1 publication Critical patent/WO1997048109A1/en

Links

Classifications

    • 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

Definitions

  • This invention relates to fluids that exhibit substantial increases in flow resistance when exposed to magnetic fields.
  • Magnetorheological fluids typically include magnetic-responsive particles dispersed or suspended in a carrier fluid. In the presence of a magnetic field, the magnetic-responsive particles become polarized and are thereby organized into chains of particles or particle fibrils within the carrier fluid. The chains of particles act to increase the apparent viscosity or flow resistance of the overall materials resulting in the development of a solid mass having a yield stress that must be exceeded to induce onset of flow of the magnetorheological fluid. The force required to exceed the yield stress is referred to as the "yield strength". In the absence of a magnetic field, the particles return to an unorganized or free state and the apparent viscosity or flow resistance of the overall materials is correspondingly reduced. Such absence of a magnetic field is referred to herein as the "off-state”.
  • Magnetorheological fluids are useful in devices or systems for controlling vibration and/or noise.
  • magnetorheological fluids are useful in providing controllable forces acting upon a piston in linear devices such as dampers, mounts and similar devices.
  • Magnetorheological fluids are also useful for providing controllable torque acting upon a rotor in rotary devices.
  • Possible linear or rotary devices could be clutches, brakes, valves, dampers, mounts and similar devices.
  • magnetorheological fluid can be subjected to shear forces, as high as 70 kPa, often significantly high, and shear rates in the order of 20,000 to 50,000 sec '1 causing extreme wear on the magnetic-responsive particles.
  • the magnetorheological fluid thickens substantially over time leading to increasing off-state viscosity.
  • the increasing off-state viscosity leads to an increase in off-state force experienced by the piston or rotor.
  • This increase in off-state force hampers the freedom of movement of the piston or rotor at off-state conditions.
  • WO 94/10694 relates to a magnetorheological fluid that includes magnetic particles in a carrier fluid wherein the magnetic particles have been provided with a protective coating that substantially encapsulates the particles.
  • Possible coating materials are said to include nonmagnetic metals, ceramics, high performance thermoplastics, and thermosetting polymers
  • US-A-4,356,098 relates to a colloidal suspension of particles having a particle size of, at most, 800 Angstroms that includes a silicone oil carrier fluid and a silicone oil-type surfactant.
  • a silicone oil carrier fluid and a silicone oil-type surfactant.
  • the patent is directed to ferrofluids, one passage mentions that the system could be used to provide a stable composition of nonmagnetic colloidal particles. Oxides and sulfides of molybdenum are included in the list of possible nonmagnetic colloidal particles.
  • US-A-4,889,647 relates to an organomolybdenum complex that is prepared by reacting a fatty oil having 12 or more carbon atoms, diethanolamine and a molybdenum source.
  • This organomolybdenum complex is said to be useful as a component in lubricating compositions for use in internal combustion engines.
  • US-A-5,412,130 relates to a process for preparing 2,4-heteroatom substituted-molybdena-3,3-dioxacycloalkane compounds. There is no mention of any use for the molybdate compounds.
  • US-A-5,271,858 and US-A-5, 326,633 relate to an electrorheological fluid that includes a carbon, glass, silicate, or ceramic particulate having an electrically conductive tin dioxide coating.
  • US-A-5, 147,573 relates to a ferrofluid that includes superparamagnetic particles having a maximum average particle size of 500 angstroms, an electrically conductive surface active agent adsorbed as a conductive shell around the superparamagnetic particles, a dispersing or suspending agent and a carrier fluid.
  • the electrically conductive surface active agent can be an alkyl or alkoxide organometallic compound.
  • the listed possibilities for the metal portion of the organometallics are titanium, antimony, tin, hafnium and zirconium.
  • US-A-5,354,488 relates to an electrorheological magnetic fluid that includes magnetizable particles, a carrier fluid and a dispersant that consists of particles having no dimensions greater than 10 nm.
  • the dispersant particles may be made of single element metals or non-metal substances such as carbon, boron, aluminum, non-magnetizable iron, germanium and silicon or inorganic compounds like metal carbides, oxides, nitrides and other salts of aluminum, boron, germanium, hafnium, iron, silicon, tantalum, titanium, tungsten, yttrium and zirconium.
  • JP-A-52-77981 relates to a dispersion of superparamagnetic colloidal in water or petroleum that includes 5 to 30 volume percent of a molybdenum or tungsten powder having particle diameters ranging from 0.1 to 10 ⁇ m.
  • the dispersion is used for sealing rotary shafts which is a well known use for ferrofluids.
  • the invention is a magnetorheological fluid that includes magnetic-responsive particles, a carrier fluid and at least one organomolybdenum additive.
  • the magnetorheological fluid of the invention exhibits superior durability because of a substantial decrease in the thickening of the fluid over a period of use.
  • a magnetorheological damper that include a housing that contains the above- described magnetorheological fluid.
  • the organomolybdenum component can be a compound or complex whose structure includes at least one molybdenum atom bonded to or coordinated with at least one organic moiety.
  • the organic moiety can be, for example, derived from a saturated or unsaturated hydrocarbon such as alkane, alkene, alkadiene or cycloalkane; an aromatic hydrocarbon such as phenol or thiophenol; an oxygen-containing compound such as carboxylic acid or anhydride, ester, ether, peroxide or alcohol; a nitrogen-containing compound such as amidine, amine or imine; or a compound containing more than one functional group such as thiocarboxylic acid, imidic acid, thiol, amide, imide, alkoxy or hydroxy amine, and amino-thiol-alcohol.
  • the precursor for the organic moiety can be a monomeric compound, an oligomer or polymer.
  • US-A-4,889,647 describes an organomolybdenum complex that is prepared by reacting a fatty oil, diethanolamine and a molybdenum source.
  • US-A-5,412,130 describes heterocyclic organomolybdates that are prepared by reacting diol, diamino-thiol-alcohol and amino-alcohol compounds with a molybdenum source in the presence of a phase transfer agent.
  • An organomolybdenum that is prepared according to US-A-4,889,647 and US- A-5,412,130 is available from R.T. Vanderbilt Inc. under the tradename
  • Organomolybdenums that also might be useful are described in US- A-5, 137,647 which describes an organomolybdenum that is prepared by reacting an amine-amide with a molybdenum source; US-A-4,990,271 which describes a molybdenum hexacarbonyl dixanthogen; US-A-4, 164,473 which describes an organomolybdenum that is prepared by reacting a hydrocarbyl substituted hydroxy alkylated amine with a molybdenum source; and US-A-2,805,997 which describes alkyl esters of molybdic acid.
  • the organomolybdenum component that is added to the magnetorheological fluid preferably is in a liquid state at ambient room temperature and does not contain any particles above molecular size.
  • the organomolybdenum can be present in an amount of 0.1 to 12, preferably 0.25 to 10, volume percent, based on the total volume of the magnetorheological fluid.
  • Especially durable magnetorheological fluids can be obtained if the organomolybdenum component is present in combination with a second additive.
  • the second additive can be present in an amount of 0.25 to 12, preferably 0.5 to 10, volume percent, based on the total volume of the magnetorheological fluid.
  • Useful second additives include phosphates and sulfur-containing compounds,.
  • phosphates include alkyl, aryl, alkylaryl, arylalkyl, amine and alkyl amine phosphates.
  • Illustrative of such phosphates are tricresyl phosphate, trixylenyl phosphate, dilauryl phosphate, octadecyl phosphate, hexadecyl phosphate, dodecyl phosphate and didodecyl phosphate.
  • a particularly preferred alkyl amine phosphate is available from R.T. Vanderbilt Inc. under the tradename Vanlube® 9123.
  • sulfur-containing compounds include thioesters such as tetrakis thioglycolate, tetrakis(3-mercaptopropionyl) pentaerithritol, ethylene glycoldimercaptoacetate, 1,2,6-hexanetriol tri thioglycolate, trimethylol ethane tri(3-mercaptopropionate), glycoldimercaptopropionate, bisthioglycolate, trimethylolethane tri thioglycolate, trimethylolpropane tris(3-mercaptopropionate) and similar compounds and thiols such as 1- dodecylthiol, 1-decanethiol, 1-methyl-l-decanethiol, 2-methyl-2-decanethiol, 1-hexadecylthiol, 2-propyl-2-decanethiol, 1-butylthiol, 2-hexadecylthiol and similar
  • the magnetic-responsive particle component of the magnetorheological material of the invention can be comprised of essentially any solid which is known to exhibit magnetorheological activity.
  • Typical magnetic-responsive particle components useful in the present invention are comprised of, for example, paramagnetic, superparamagnetic or ferromagnetic compounds. Superparamagnetic compounds are especially preferred.
  • Specific examples of magnetic- responsive particle components include particles comprised of materials such as iron, iron oxide, iron nitride, iron carbide, carbonyl iron, chromium dioxide, low carbon steel, silicon steel, nickel, cobalt, and mixtures thereof.
  • the iron oxide includes all known pure iron oxides, such as Fe2 ⁇ 3 and Fe3 ⁇ 4, as well as those containing small amounts of other elements, such as manganese, zinc or barium.
  • iron oxide examples include ferrites and magnetites.
  • the magnetic- responsive particle component can be comprised of any of the known alloys of iron, such as those containing aluminum, silicon, cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese and/or copper.
  • the magnetic-responsive particle component can also be comprised of the specific iron-cobalt and iron-nickel alloys described in US-A-5,382,373.
  • the iron-cobalt alloys useful in the invention have an iron:cobalt ratio ranging from about 30:70 to 95:5, preferably ranging from about 50:50 to 85:15, while the iron-nickel alloys have an iron:nickel ratio ranging from about 90:10 to 99:1, preferably ranging from about 94:6 to 97:3.
  • the iron alloys may contain a small amount of other elements, such as vanadium, chromium, etc., in order to improve the ductility and mechanical properties of the alloys. These other elements are typically present in an amount that is less than about 3.0% by weight.
  • the iron-cobalt alloys are presently preferred over the iron-nickel alloys for utilization as the particle component in a magnetorheological material.
  • the preferred iron-cobalt alloys can be commercially obtained under the tradenames HYPERCO (Carpenter Technology), HYPERM (F. Krupp Widiafabrik), SUPERMENDUR (Arnold Eng.) and 2V-PERMENDUR (Western Electric).
  • the magnetic-responsive particle component of the invention is typically in the form of a metal powder which can be prepared by processes well known to those skilled in the art. Typical methods for the preparation of metal powders include the reduction of metal oxides, grinding or attrition, electrolytic deposition, metal carbonyl decomposition, rapid solidification, or smelt processing. Various metal powders that are commercially available include straight iron powders, reduced iron powders, insulated reduced iron powders, cobalt powders, and various alloy powders such as [48%]Fe/[50%]Co/[2%]V powder available from UltraFine Powder Technologies.
  • the preferred magnetic-responsive particles are those that contain a majority amount of iron in some form.
  • Carbonyl iron powders that are high purity iron particles made by the thermal decomposition of iron pentacarbonyl are particularly preferred.
  • Carbonyl iron of the preferred form is commercially available from ISP Technologies, GAF Corporation and BASF Corporation.
  • the particle size should be selected so that it exhibits multi-domain characteristics when subjected to a magnetic field.
  • the magnetic- responsive particles should have an average particle size distribution of at least about 0.1 ⁇ m, preferably at least about 1 ⁇ m.
  • the average particle size distribution should range from about 0.1 to about 500 ⁇ m, with from about 1 to about 500 ⁇ m being preferred, about 1 to about 250 ⁇ m being particularly preferred, and from about 1 to about 100 ⁇ m being especially preferred.
  • the amount of magnetic-responsive particles in the magnetorheological fluid depends upon the desired magnetic activity and viscosity of the fluid, but should be from about 5 to about 50, preferably from about 15 to 40, percent by volume based on the total volume of the magnetorheological fluid.
  • the carrier component is a fluid that forms the continuous phase of the magnetorheological fluid.
  • Suitable carrier fluids may be found to exist in any of the classes of oils or liquids known to be carrier fluids for magnetorheological fluids such as natural fatty oils, mineral oils, polyphenylethers, dibasic acid esters, neopentylpolyol esters, phosphate esters, polyesters (such as perfluorinated polyesters), synthetic cycloparaffins and synthetic paraffins, unsaturated hydrocarbon oils, monobasic acid esters, glycol esters and ethers, synthetic hydrocarbon oils, perfluorinated polyethers and halogenated hydrocarbons, as well as mixtures and derivatives thereof.
  • the carrier component may be a mixture of any of these classes of fluids.
  • the preferred carrier component is non ⁇ volatile, non-polar and does not include any significant amount of water.
  • the carrier component (and thus the magnetorheological fluid) particularly preferably should not include any volatile solvents commonly used in lacquers or compositions that are coated onto a surface and then dried such as toluene, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone and acetone. Descriptions of suitable carrier fluids can be found, for example, in US-A-2,751,352 and US-A-5,382,373, both hereby incorporated by reference.
  • Hydrocarbons such as mineral oils, paraffins, cycloparaffins (also known as naphthenic oils) and synthetic hydrocarbons are the preferred classes of carrier fluids.
  • the synthetic hydrocarbon oils include those oils derived from oligomerization of olefins such as polybutenes and oils derived from high alpha olefins of from 8 to 20 carbon atoms by acid catalyzed dimerization and by oligomerization using trialuminum alkyls as catalysts.
  • Poly- ⁇ -olefin is a particularly preferred carrier fluid.
  • Carrier fluids appropriate to the present invention may be prepared by methods well known in the art and many are commercially available.
  • the carrier fluid of the present invention is typically utilized in an amount ranging from about 50 to 95, preferably from about 60 to 85, percent by volume of the total magnetorheological fluid.
  • the magnetorheological fluid can optionally include other additives such as a thixotropic agent, a carboxylate soap, an antioxidant, a lubricant and a viscosity modifier. If present, the amount of these optional additives typically ranges from about 0.25 to about 10, preferably about 0.5 to about 7.5, volume percent based on the total volume of the magnetorheological fluid.
  • thixotropic agents are described, for example, in WO 94/10693 and commonly-assigned U.S. Patent Application Serial No. 08/575,240, incorporated herein by reference.
  • thixotropic agents include polymer- modified metal oxides.
  • the polymer-modified metal oxide can be prepared by reacting a metal oxide powder with a polymeric compound that is compatible with the carrier fluid and capable of shielding substantially all of the hydrogen-bonding sites or groups on the surface of the metal oxide from any interaction with other molecules.
  • Illustrative metal oxide powders include precipitated silica gel, fumed or pyrogenic silica, silica gel, titanium dioxide, and iron oxides such as ferrites or magnetites.
  • polymeric compounds useful in forming the polymer-modified metal oxides include siloxane oligomers, mineral oils and paraffin oils, with siloxane oligomers being preferred.
  • the metal oxide powder may be surface-treated with the polymeric compound through techniques well known to those skilled in the art of surface chemistry.
  • a polymer-modified metal oxide, in the form of fumed silica treated with a siloxane oligomer, can be commercially obtained under the trade names AEROSIL R-202 and CABOSIL TS-720 from DeGussa Corporation and Cabot Corporation, respectively.
  • Examples of the carboxylate soap include lithium stearate, calcium stearate, aluminum stearate, ferrous oleate, ferrous naphthenate, zinc stearate, sodium stearate, strontium stearate and mixtures thereof.
  • the viscosity of the magnetorheological fluid is dependent upon the specific use of the magnetorheological fluid. In the instance of a magnetorheological fluid that is used with a damper the carrier fluid should have a viscosity of 6 to 500, preferably 15 to 395, Pa-sec measured at 40°C in the off-state.
  • the magnetorheological fluid can be used in any controllable device such as dampers, mounts, clutches, brakes, valves and similar devices.
  • These magnetorheological devices include a housing or chamber that contains the magnetorheological fluid.
  • Such devices are known and are described, for example, in US-A-5,277,281; US-A-5,284,330; US-A-5,398,917; US-A-5,492,312; 5,176,368; 5,257,681; 5,353,839; and 5,460,585, all incorporated herein by reference, and PCT published patent application WO 96/07836.
  • the fluid is particularly suitable for use in devices that require exceptional durability such as dampers.
  • Damper means an apparatus for damping motion between two relatively movable members. Dampers include, but are not limited to, shock absorbers such as automotive shock absorbers.
  • shock absorbers such as automotive shock absorbers.
  • the magnetorheological dampers described in US-A-5,277,281 and US-A-5,284,330, both incorporated herein by reference, are illustrative of magnetorheological dampers that could use the magnetorheological fluid.
  • magnetorheological fluid examples of the magnetorheological fluid were prepared as follows:
  • a synthetic hydrocarbon oil derived from poly-oc-olefin (available from
  • Albemarle Corp. under the tradename DURASYN 164) was homogeneously mixed with the organomolybdenum additive and, in Fluids 2 and 3 with a second additive, in the amounts shown in Table 1.
  • carbonyl iron available from GAF Corp. under the tradename R2430
  • Fumed silica available from Cabot Corp. under the tradename CAB-O-SIL TS-720
  • the full formulation then was mixed while cooling with an ice bath to maintain the temperature near ambient.
  • Table 1 shows the composition of the fluids prepared with all quantities in volume percent based on the total volume of the final fluid.
  • a parafin/naphthenic oil available from Penreco Corp. under the trademark DRAKEOL 10B was used instead of DURASYN 164.

Abstract

A magnetorheological fluid tht includes magnetic-responsive particles, a carrier fluid and an organomolybdenum. The organomolybdenum preferably includes at least one molydenum atom bonded to at least one organic moiety wherein the organic moiety can be derived from a precursor selected from the group consisting of a saturated or unsaturated hydrocarbon, an aromatic hydrocarbon, an oxygen-containing compound, a nitrogen-containing compound and a compound containing more than one functional group.

Description

ORGANOMOLYBDENUM-CONTAINING MAGNETORHEOLOGICAL
FLUID
Background and Summary of the Invention
This invention relates to fluids that exhibit substantial increases in flow resistance when exposed to magnetic fields.
Fluid compositions that undergo a change in apparent viscosity in the presence of a magnetic field are commonly referred to as Bingham magnetic fluids or magnetorheological fluids. Magnetorheological fluids typically include magnetic-responsive particles dispersed or suspended in a carrier fluid. In the presence of a magnetic field, the magnetic-responsive particles become polarized and are thereby organized into chains of particles or particle fibrils within the carrier fluid. The chains of particles act to increase the apparent viscosity or flow resistance of the overall materials resulting in the development of a solid mass having a yield stress that must be exceeded to induce onset of flow of the magnetorheological fluid. The force required to exceed the yield stress is referred to as the "yield strength". In the absence of a magnetic field, the particles return to an unorganized or free state and the apparent viscosity or flow resistance of the overall materials is correspondingly reduced. Such absence of a magnetic field is referred to herein as the "off-state".
Magnetorheological fluids are useful in devices or systems for controlling vibration and/or noise. For example, magnetorheological fluids are useful in providing controllable forces acting upon a piston in linear devices such as dampers, mounts and similar devices. Magnetorheological fluids are also useful for providing controllable torque acting upon a rotor in rotary devices. Possible linear or rotary devices could be clutches, brakes, valves, dampers, mounts and similar devices. In these applications magnetorheological fluid can be subjected to shear forces, as high as 70 kPa, often significantly high, and shear rates in the order of 20,000 to 50,000 sec'1 causing extreme wear on the magnetic-responsive particles. As a result, the magnetorheological fluid thickens substantially over time leading to increasing off-state viscosity. The increasing off-state viscosity leads to an increase in off-state force experienced by the piston or rotor. This increase in off-state force hampers the freedom of movement of the piston or rotor at off-state conditions. In addition, it is desirable to maximize the ratio of on-state force to off-state force in order to maximize the controllability offered by the device. Since the on-state force is dependent upon the magnitude of the applied magnetic field, the on-state force should remain constant at any given applied magnetic field. If the off-state force increases over time because the off-state viscosity is increasing but the on- state force remains constant, the on-state/off-state ratio will decrease. This on-state/off-state ratio decrease results in undesirable minimization of the controllability offered by the device. A more durable magnetorheological fluid that does not thicken over an extended period of time, preferably over the life of the device that includes the fluid, would be very useful. Magnetorheological fluids are described, for example, in US-A-
5,382,373 and published PCT International Patent Applications WO 94/10692, WO 94/10693 and WO 94/10694.
WO 94/10694 relates to a magnetorheological fluid that includes magnetic particles in a carrier fluid wherein the magnetic particles have been provided with a protective coating that substantially encapsulates the particles. Possible coating materials are said to include nonmagnetic metals, ceramics, high performance thermoplastics, and thermosetting polymers
US-A-4,356,098 relates to a colloidal suspension of particles having a particle size of, at most, 800 Angstroms that includes a silicone oil carrier fluid and a silicone oil-type surfactant. Although the patent is directed to ferrofluids, one passage mentions that the system could be used to provide a stable composition of nonmagnetic colloidal particles. Oxides and sulfides of molybdenum are included in the list of possible nonmagnetic colloidal particles.
US-A-4,889,647 relates to an organomolybdenum complex that is prepared by reacting a fatty oil having 12 or more carbon atoms, diethanolamine and a molybdenum source. This organomolybdenum complex is said to be useful as a component in lubricating compositions for use in internal combustion engines.
US-A-5,412,130 relates to a process for preparing 2,4-heteroatom substituted-molybdena-3,3-dioxacycloalkane compounds. There is no mention of any use for the molybdate compounds.
US-A-5,271,858 and US-A-5, 326,633 relate to an electrorheological fluid that includes a carbon, glass, silicate, or ceramic particulate having an electrically conductive tin dioxide coating.
US-A-5, 147,573 relates to a ferrofluid that includes superparamagnetic particles having a maximum average particle size of 500 angstroms, an electrically conductive surface active agent adsorbed as a conductive shell around the superparamagnetic particles, a dispersing or suspending agent and a carrier fluid. The electrically conductive surface active agent can be an alkyl or alkoxide organometallic compound. The listed possibilities for the metal portion of the organometallics are titanium, antimony, tin, hafnium and zirconium.
US-A-5,354,488 relates to an electrorheological magnetic fluid that includes magnetizable particles, a carrier fluid and a dispersant that consists of particles having no dimensions greater than 10 nm. The dispersant particles may be made of single element metals or non-metal substances such as carbon, boron, aluminum, non-magnetizable iron, germanium and silicon or inorganic compounds like metal carbides, oxides, nitrides and other salts of aluminum, boron, germanium, hafnium, iron, silicon, tantalum, titanium, tungsten, yttrium and zirconium.
JP-A-52-77981 relates to a dispersion of superparamagnetic colloidal in water or petroleum that includes 5 to 30 volume percent of a molybdenum or tungsten powder having particle diameters ranging from 0.1 to 10 μm. The dispersion is used for sealing rotary shafts which is a well known use for ferrofluids. Summary of the Invention
The invention is a magnetorheological fluid that includes magnetic-responsive particles, a carrier fluid and at least one organomolybdenum additive.
The magnetorheological fluid of the invention exhibits superior durability because of a substantial decrease in the thickening of the fluid over a period of use. There also is provided according to the invention a magnetorheological damper that include a housing that contains the above- described magnetorheological fluid.
Detailed Description of the Preferred Embodiments
The organomolybdenum component can be a compound or complex whose structure includes at least one molybdenum atom bonded to or coordinated with at least one organic moiety. The organic moiety can be, for example, derived from a saturated or unsaturated hydrocarbon such as alkane, alkene, alkadiene or cycloalkane; an aromatic hydrocarbon such as phenol or thiophenol; an oxygen-containing compound such as carboxylic acid or anhydride, ester, ether, peroxide or alcohol; a nitrogen-containing compound such as amidine, amine or imine; or a compound containing more than one functional group such as thiocarboxylic acid, imidic acid, thiol, amide, imide, alkoxy or hydroxy amine, and amino-thiol-alcohol. The precursor for the organic moiety can be a monomeric compound, an oligomer or polymer. A heteroatom such as =O, -S or ≡N also can be bonded to or coordinated with the molybdenum atom in addition to the organic moiety.
A particularly preferred group of organomolybdenums is described in US-A-4,889,647 and US-A-5,412,130, both incorporated herein by reference. US-A-4,889,647 describes an organomolybdenum complex that is prepared by reacting a fatty oil, diethanolamine and a molybdenum source. US-A-5,412,130 describes heterocyclic organomolybdates that are prepared by reacting diol, diamino-thiol-alcohol and amino-alcohol compounds with a molybdenum source in the presence of a phase transfer agent. An organomolybdenum that is prepared according to US-A-4,889,647 and US- A-5,412,130 is available from R.T. Vanderbilt Inc. under the tradename
Molyvan® 855.
Organomolybdenums that also might be useful are described in US- A-5, 137,647 which describes an organomolybdenum that is prepared by reacting an amine-amide with a molybdenum source; US-A-4,990,271 which describes a molybdenum hexacarbonyl dixanthogen; US-A-4, 164,473 which describes an organomolybdenum that is prepared by reacting a hydrocarbyl substituted hydroxy alkylated amine with a molybdenum source; and US-A-2,805,997 which describes alkyl esters of molybdic acid. The organomolybdenum component that is added to the magnetorheological fluid preferably is in a liquid state at ambient room temperature and does not contain any particles above molecular size.
The organomolybdenum can be present in an amount of 0.1 to 12, preferably 0.25 to 10, volume percent, based on the total volume of the magnetorheological fluid.
Especially durable magnetorheological fluids can be obtained if the organomolybdenum component is present in combination with a second additive. The second additive can be present in an amount of 0.25 to 12, preferably 0.5 to 10, volume percent, based on the total volume of the magnetorheological fluid.
Useful second additives include phosphates and sulfur-containing compounds,. Examples of phosphates include alkyl, aryl, alkylaryl, arylalkyl, amine and alkyl amine phosphates. Illustrative of such phosphates are tricresyl phosphate, trixylenyl phosphate, dilauryl phosphate, octadecyl phosphate, hexadecyl phosphate, dodecyl phosphate and didodecyl phosphate. A particularly preferred alkyl amine phosphate is available from R.T. Vanderbilt Inc. under the tradename Vanlube® 9123.
Examples of sulfur-containing compounds include thioesters such as tetrakis thioglycolate, tetrakis(3-mercaptopropionyl) pentaerithritol, ethylene glycoldimercaptoacetate, 1,2,6-hexanetriol tri thioglycolate, trimethylol ethane tri(3-mercaptopropionate), glycoldimercaptopropionate, bisthioglycolate, trimethylolethane tri thioglycolate, trimethylolpropane tris(3-mercaptopropionate) and similar compounds and thiols such as 1- dodecylthiol, 1-decanethiol, 1-methyl-l-decanethiol, 2-methyl-2-decanethiol, 1-hexadecylthiol, 2-propyl-2-decanethiol, 1-butylthiol, 2-hexadecylthiol and similar compounds.
The magnetic-responsive particle component of the magnetorheological material of the invention can be comprised of essentially any solid which is known to exhibit magnetorheological activity. Typical magnetic-responsive particle components useful in the present invention are comprised of, for example, paramagnetic, superparamagnetic or ferromagnetic compounds. Superparamagnetic compounds are especially preferred. Specific examples of magnetic- responsive particle components include particles comprised of materials such as iron, iron oxide, iron nitride, iron carbide, carbonyl iron, chromium dioxide, low carbon steel, silicon steel, nickel, cobalt, and mixtures thereof. The iron oxide includes all known pure iron oxides, such as Fe2θ3 and Fe3θ4, as well as those containing small amounts of other elements, such as manganese, zinc or barium. Specific examples of iron oxide include ferrites and magnetites. In addition, the magnetic- responsive particle component can be comprised of any of the known alloys of iron, such as those containing aluminum, silicon, cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese and/or copper.
The magnetic-responsive particle component can also be comprised of the specific iron-cobalt and iron-nickel alloys described in US-A-5,382,373. The iron-cobalt alloys useful in the invention have an iron:cobalt ratio ranging from about 30:70 to 95:5, preferably ranging from about 50:50 to 85:15, while the iron-nickel alloys have an iron:nickel ratio ranging from about 90:10 to 99:1, preferably ranging from about 94:6 to 97:3. The iron alloys may contain a small amount of other elements, such as vanadium, chromium, etc., in order to improve the ductility and mechanical properties of the alloys. These other elements are typically present in an amount that is less than about 3.0% by weight. Due to their ability to generate somewhat higher yield stresses, the iron-cobalt alloys are presently preferred over the iron-nickel alloys for utilization as the particle component in a magnetorheological material. Examples of the preferred iron-cobalt alloys can be commercially obtained under the tradenames HYPERCO (Carpenter Technology), HYPERM (F. Krupp Widiafabrik), SUPERMENDUR (Arnold Eng.) and 2V-PERMENDUR (Western Electric).
The magnetic-responsive particle component of the invention is typically in the form of a metal powder which can be prepared by processes well known to those skilled in the art. Typical methods for the preparation of metal powders include the reduction of metal oxides, grinding or attrition, electrolytic deposition, metal carbonyl decomposition, rapid solidification, or smelt processing. Various metal powders that are commercially available include straight iron powders, reduced iron powders, insulated reduced iron powders, cobalt powders, and various alloy powders such as [48%]Fe/[50%]Co/[2%]V powder available from UltraFine Powder Technologies.
The preferred magnetic-responsive particles are those that contain a majority amount of iron in some form. Carbonyl iron powders that are high purity iron particles made by the thermal decomposition of iron pentacarbonyl are particularly preferred. Carbonyl iron of the preferred form is commercially available from ISP Technologies, GAF Corporation and BASF Corporation.
The particle size should be selected so that it exhibits multi-domain characteristics when subjected to a magnetic field. The magnetic- responsive particles should have an average particle size distribution of at least about 0.1 μm, preferably at least about 1 μm. The average particle size distribution should range from about 0.1 to about 500 μm, with from about 1 to about 500 μm being preferred, about 1 to about 250 μm being particularly preferred, and from about 1 to about 100 μm being especially preferred.
The amount of magnetic-responsive particles in the magnetorheological fluid depends upon the desired magnetic activity and viscosity of the fluid, but should be from about 5 to about 50, preferably from about 15 to 40, percent by volume based on the total volume of the magnetorheological fluid.
The carrier component is a fluid that forms the continuous phase of the magnetorheological fluid. Suitable carrier fluids may be found to exist in any of the classes of oils or liquids known to be carrier fluids for magnetorheological fluids such as natural fatty oils, mineral oils, polyphenylethers, dibasic acid esters, neopentylpolyol esters, phosphate esters, polyesters (such as perfluorinated polyesters), synthetic cycloparaffins and synthetic paraffins, unsaturated hydrocarbon oils, monobasic acid esters, glycol esters and ethers, synthetic hydrocarbon oils, perfluorinated polyethers and halogenated hydrocarbons, as well as mixtures and derivatives thereof. The carrier component may be a mixture of any of these classes of fluids. The preferred carrier component is non¬ volatile, non-polar and does not include any significant amount of water. The carrier component (and thus the magnetorheological fluid) particularly preferably should not include any volatile solvents commonly used in lacquers or compositions that are coated onto a surface and then dried such as toluene, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone and acetone. Descriptions of suitable carrier fluids can be found, for example, in US-A-2,751,352 and US-A-5,382,373, both hereby incorporated by reference. Hydrocarbons, such as mineral oils, paraffins, cycloparaffins (also known as naphthenic oils) and synthetic hydrocarbons are the preferred classes of carrier fluids. The synthetic hydrocarbon oils include those oils derived from oligomerization of olefins such as polybutenes and oils derived from high alpha olefins of from 8 to 20 carbon atoms by acid catalyzed dimerization and by oligomerization using trialuminum alkyls as catalysts. Poly-α-olefin is a particularly preferred carrier fluid. Carrier fluids appropriate to the present invention may be prepared by methods well known in the art and many are commercially available.
The carrier fluid of the present invention is typically utilized in an amount ranging from about 50 to 95, preferably from about 60 to 85, percent by volume of the total magnetorheological fluid.
The magnetorheological fluid can optionally include other additives such as a thixotropic agent, a carboxylate soap, an antioxidant, a lubricant and a viscosity modifier. If present, the amount of these optional additives typically ranges from about 0.25 to about 10, preferably about 0.5 to about 7.5, volume percent based on the total volume of the magnetorheological fluid.
Useful thixotropic agents are described, for example, in WO 94/10693 and commonly-assigned U.S. Patent Application Serial No. 08/575,240, incorporated herein by reference. Such thixotropic agents include polymer- modified metal oxides. The polymer-modified metal oxide can be prepared by reacting a metal oxide powder with a polymeric compound that is compatible with the carrier fluid and capable of shielding substantially all of the hydrogen-bonding sites or groups on the surface of the metal oxide from any interaction with other molecules. Illustrative metal oxide powders include precipitated silica gel, fumed or pyrogenic silica, silica gel, titanium dioxide, and iron oxides such as ferrites or magnetites. Examples of polymeric compounds useful in forming the polymer-modified metal oxides include siloxane oligomers, mineral oils and paraffin oils, with siloxane oligomers being preferred. The metal oxide powder may be surface-treated with the polymeric compound through techniques well known to those skilled in the art of surface chemistry. A polymer-modified metal oxide, in the form of fumed silica treated with a siloxane oligomer, can be commercially obtained under the trade names AEROSIL R-202 and CABOSIL TS-720 from DeGussa Corporation and Cabot Corporation, respectively.
Examples of the carboxylate soap include lithium stearate, calcium stearate, aluminum stearate, ferrous oleate, ferrous naphthenate, zinc stearate, sodium stearate, strontium stearate and mixtures thereof. The viscosity of the magnetorheological fluid is dependent upon the specific use of the magnetorheological fluid. In the instance of a magnetorheological fluid that is used with a damper the carrier fluid should have a viscosity of 6 to 500, preferably 15 to 395, Pa-sec measured at 40°C in the off-state.
The magnetorheological fluid can be used in any controllable device such as dampers, mounts, clutches, brakes, valves and similar devices. These magnetorheological devices include a housing or chamber that contains the magnetorheological fluid. Such devices are known and are described, for example, in US-A-5,277,281; US-A-5,284,330; US-A-5,398,917; US-A-5,492,312; 5,176,368; 5,257,681; 5,353,839; and 5,460,585, all incorporated herein by reference, and PCT published patent application WO 96/07836. The fluid is particularly suitable for use in devices that require exceptional durability such as dampers. As used herein, "damper" means an apparatus for damping motion between two relatively movable members. Dampers include, but are not limited to, shock absorbers such as automotive shock absorbers. The magnetorheological dampers described in US-A-5,277,281 and US-A-5,284,330, both incorporated herein by reference, are illustrative of magnetorheological dampers that could use the magnetorheological fluid.
Examples of the magnetorheological fluid were prepared as follows:
A synthetic hydrocarbon oil derived from poly-oc-olefin (available from
Albemarle Corp. under the tradename DURASYN 164) was homogeneously mixed with the organomolybdenum additive and, in Fluids 2 and 3 with a second additive, in the amounts shown in Table 1. To this homogeneous mixture, carbonyl iron (available from GAF Corp. under the tradename R2430) in the amount shown in Table 1 was added while continuing mixing. Fumed silica (available from Cabot Corp. under the tradename CAB-O-SIL TS-720) in the amount shown in Table 1 was then added while continuing mixing. The full formulation then was mixed while cooling with an ice bath to maintain the temperature near ambient. Table 1 shows the composition of the fluids prepared with all quantities in volume percent based on the total volume of the final fluid. In Fluid 3 a parafin/naphthenic oil ( available from Penreco Corp. under the trademark DRAKEOL 10B) was used instead of DURASYN 164.
Table 1
Figure imgf000013_0001

Claims

ClaimsWhat is claimed is:
1. A magnetorheological fluid comprising magnetic-responsive particles, a carrier fluid and at least one organomolybdenum.
2. A magnetorheological fluid according to claim 1, wherein the organomolybdenum is selected from the group consisting of an organomolybdenum complex prepared by reacting a fatty oil, diethanolamine and a molybdenum source; a heterocyclic molybdenum prepared by reacting a diol, a diamino-thiol-alcohol, an amino-alcohol and a molybdenum source; and an organomolybdenum prepared by reacting an amine-amide with a molybdenum source.
3. A magnetorheological fluid according to claim 1, wherein the organomolybdenum present in amount of 0.1 to 12 volume percent, based on the total volume of the magnetorheological fluid.
4. A magnetorheological fluid according to claim 1, wherein the magnetic-responsive particles have an average particle size of 0.1 to 500 μm.
5. A magnetorheological fluid according to claim 1, wherein the carrier fluid comprises at least one fluid selected from the group consisting of natural fatty oil, mineral oil, polyphenylether, dibasic acid ester, neopentylpolyol ester, phosphate ester, polyester, cycloparaffin oil, paraffin oil, unsaturated hydrocarbon oil, synthetic hydrocarbon oil, napthenic oil, monobasic acid ester, glycol ester, glycol ether, synthetic hydrocarbon, perfluorinated polyether and halogenated hydrocarbon.
6. A magnetorheological fluid according to claim 1, further comprising at least one additive selected from the group consisting of a phosphate and a sulfur-containing compound.
7. A magnetorheological fluid according to claim 6, wherein the phosphate is selected from the group consisting of alkyl, aryl, alkylaryl, arylalkyl, amine and alkyl amine phosphate.
8. A magnetorheological fluid according to claim 6 wherein the sulfur-containing compound is selected from the group consisting of thiol and thioester.
9. A magnetorheological fluid according to any one of claims 1 or
6, further comprising at least one carboxylate soap.
10. A magnetorheological fluid according to claim 9 wherein the carboxylate soap is selected from the group consisting of lithium stearate, calcium stearate, aluminum stearate, ferrous oleate, ferrous naphthenate, zinc stearate, sodium stearate and strontium stearate.
PCT/US1997/009761 1996-06-13 1997-06-10 Organomolybdenum-containing magnetorheological fluid WO1997048109A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP97928864A EP0904591B1 (en) 1996-06-13 1997-06-10 Organomolybdenum-containing magnetorheological fluid
DE69737625T DE69737625T2 (en) 1996-06-13 1997-06-10 ORGANOMOLYBDEDE CONTAINING MAGNETORHEOLOGICAL LIQUID
JP50169098A JP3893449B2 (en) 1996-06-13 1997-06-10 Magnetorheological fluid containing organomolybdenum

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/664,075 1996-06-13
US08/664,075 US5705085A (en) 1996-06-13 1996-06-13 Organomolybdenum-containing magnetorheological fluid

Publications (1)

Publication Number Publication Date
WO1997048109A1 true WO1997048109A1 (en) 1997-12-18

Family

ID=24664417

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/009761 WO1997048109A1 (en) 1996-06-13 1997-06-10 Organomolybdenum-containing magnetorheological fluid

Country Status (6)

Country Link
US (1) US5705085A (en)
EP (1) EP0904591B1 (en)
JP (1) JP3893449B2 (en)
CA (1) CA2258050A1 (en)
DE (1) DE69737625T2 (en)
WO (1) WO1997048109A1 (en)

Families Citing this family (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6340080B1 (en) 1997-10-29 2002-01-22 Lord Corporation Apparatus including a matrix structure and apparatus
US6202806B1 (en) 1997-10-29 2001-03-20 Lord Corporation Controllable device having a matrix medium retaining structure
US6302249B1 (en) 1999-03-08 2001-10-16 Lord Corporation Linear-acting controllable pneumatic actuator and motion control apparatus including a field responsive medium and control method therefor
US6234060B1 (en) 1999-03-08 2001-05-22 Lord Corporation Controllable pneumatic apparatus including a rotary-acting brake with field responsive medium and control method therefor
US6547983B2 (en) 1999-12-14 2003-04-15 Delphi Technologies, Inc. Durable magnetorheological fluid compositions
US6599439B2 (en) 1999-12-14 2003-07-29 Delphi Technologies, Inc. Durable magnetorheological fluid compositions
AU2001241642A1 (en) 2000-02-18 2001-08-27 The Board Of Regents Of The University And Community College System Of Nevada Magnetorheological polymer gels
US6818143B2 (en) * 2000-04-07 2004-11-16 Delphi Technologies, Inc. Durable magnetorheological fluid
US7217372B2 (en) 2000-05-03 2007-05-15 Lord Corporation Magnetorheological composition
US6395193B1 (en) 2000-05-03 2002-05-28 Lord Corporation Magnetorheological compositions
US6475404B1 (en) 2000-05-03 2002-11-05 Lord Corporation Instant magnetorheological fluid mix
US20030034475A1 (en) * 2001-08-06 2003-02-20 Ulicny John C. Magnetorheological fluids with a molybdenum-amine complex
US6929756B2 (en) * 2001-08-06 2005-08-16 General Motors Corporation Magnetorheological fluids with a molybdenum-amine complex
US20040040800A1 (en) * 2002-07-31 2004-03-04 George Anastas System and method for providing passive haptic feedback
US7101487B2 (en) * 2003-05-02 2006-09-05 Ossur Engineering, Inc. Magnetorheological fluid compositions and prosthetic knees utilizing same
EP1816545A3 (en) * 2003-05-30 2007-08-15 Immersion Corporation System and method for low power haptic feedback
FR2860798A1 (en) * 2003-10-10 2005-04-15 Nicolas Triboulot New primer or coating composition containing synthetic resin binder, diluent and iron filings with a specific particle size, used for making non-metallic surfaces sensitive to magnetism, e.g. for fixing magnetic objects to walls
WO2005037966A1 (en) * 2003-10-15 2005-04-28 Ashland Inc. Shock absorber fluid composition containing nanostuctures
US7070708B2 (en) * 2004-04-30 2006-07-04 Delphi Technologies, Inc. Magnetorheological fluid resistant to settling in natural rubber devices
US7522152B2 (en) * 2004-05-27 2009-04-21 Immersion Corporation Products and processes for providing haptic feedback in resistive interface devices
US20050274454A1 (en) * 2004-06-09 2005-12-15 Extrand Charles W Magneto-active adhesive systems
US7198137B2 (en) * 2004-07-29 2007-04-03 Immersion Corporation Systems and methods for providing haptic feedback with position sensing
US8441433B2 (en) * 2004-08-11 2013-05-14 Immersion Corporation Systems and methods for providing friction in a haptic feedback device
US9495009B2 (en) 2004-08-20 2016-11-15 Immersion Corporation Systems and methods for providing haptic effects
US8013847B2 (en) * 2004-08-24 2011-09-06 Immersion Corporation Magnetic actuator for providing haptic feedback
US8803796B2 (en) 2004-08-26 2014-08-12 Immersion Corporation Products and processes for providing haptic feedback in a user interface
US20060049010A1 (en) * 2004-09-03 2006-03-09 Olien Neil T Device and method for providing resistive and vibrotactile effects
US8002089B2 (en) * 2004-09-10 2011-08-23 Immersion Corporation Systems and methods for providing a haptic device
US9046922B2 (en) * 2004-09-20 2015-06-02 Immersion Corporation Products and processes for providing multimodal feedback in a user interface device
US7764268B2 (en) * 2004-09-24 2010-07-27 Immersion Corporation Systems and methods for providing a haptic device
US7669708B2 (en) * 2006-08-31 2010-03-02 Martin Engineering Company Bulk material handling system and control
US7556140B2 (en) * 2006-08-31 2009-07-07 Martin Engineering Company Bulk material handling system
FR2955404B1 (en) * 2010-01-18 2012-01-27 Commissariat Energie Atomique FLUID ACTUATOR AND DISPLAY DEVICE WITH FLUID ACTUATORS
US8205741B2 (en) 2010-08-06 2012-06-26 Martin Engineering Company Method of adjusting conveyor belt scrapers and open loop control system for conveyor belt scrapers
JP5587734B2 (en) * 2010-10-27 2014-09-10 協同油脂株式会社 Magnetorheological fluid composition
BR112013019906A2 (en) 2011-02-04 2017-07-04 Lord Corp polyols and their use in lubricating and drilling fluid hydrocarbons
US11518957B2 (en) 2016-02-29 2022-12-06 Lord Corporation Additive for magnetorheological fluids

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4957644A (en) * 1986-05-13 1990-09-18 Price John T Magnetically controllable couplings containing ferrofluids
WO1990015423A1 (en) * 1989-06-05 1990-12-13 Omni Quest Corporation Superparamagnetic liquid colloids
WO1994010694A1 (en) * 1992-10-30 1994-05-11 Lord Corporation Magnetorheological materials utilizing surface-modified particles
US5382373A (en) * 1992-10-30 1995-01-17 Lord Corporation Magnetorheological materials based on alloy particles

Family Cites Families (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2886151A (en) * 1949-01-07 1959-05-12 Wefco Inc Field responsive fluid couplings
NL88348C (en) * 1951-08-23
US2805996A (en) * 1954-09-20 1957-09-10 Pennsalt Chemicals Corp Process for the production of oil soluble amine complexes and compositions containing such complexes
JPS52125479A (en) * 1976-04-14 1977-10-21 Inoue Japax Res Inc Production of magnetic fluid
US4164473A (en) * 1977-10-20 1979-08-14 Exxon Research & Engineering Co. Organo molybdenum friction reducing antiwear additives
US4356098A (en) * 1979-11-08 1982-10-26 Ferrofluidics Corporation Stable ferrofluid compositions and method of making same
US4889647A (en) * 1985-11-14 1989-12-26 R. T. Vanderbilt Company, Inc. Organic molybdenum complexes
JPS62195729A (en) * 1986-02-20 1987-08-28 Hitachi Maxell Ltd Magnetic recording medium
US5271858A (en) * 1986-03-24 1993-12-21 Ensci Inc. Field dependent fluids containing electrically conductive tin oxide coated materials
US5326633A (en) * 1986-03-24 1994-07-05 Ensci, Inc. Coated substrates
US5213704A (en) * 1988-05-13 1993-05-25 International Business Machines Corporation Process for making a compliant thermally conductive compound
US5094769A (en) * 1988-05-13 1992-03-10 International Business Machines Corporation Compliant thermally conductive compound
US4990271A (en) * 1989-09-07 1991-02-05 Exxon Research And Engineering Company Antiwear, antioxidant and friction reducing additive for lubricating oils
US5143637A (en) * 1990-02-20 1992-09-01 Nippon Seiko Kabushiki Kaisha Magnetic fluid composition
US5147573A (en) * 1990-11-26 1992-09-15 Omni Quest Corporation Superparamagnetic liquid colloids
US5137647A (en) * 1991-12-09 1992-08-11 R. T. Vanderbilt Company, Inc. Organic molybdenum complexes
JPH05277981A (en) * 1992-04-02 1993-10-26 Sony Corp Robot arm
JP3241726B2 (en) * 1992-04-14 2001-12-25 バイロコープ サイエンティフィク，インコーポレイティド Magnetorheological fluid and method for producing the same
US5354488A (en) * 1992-10-07 1994-10-11 Trw Inc. Fluid responsive to a magnetic field
RU2106710C1 (en) * 1992-10-30 1998-03-10 Лорд Корпорейшн Magnetorheological material
WO1994010693A1 (en) * 1992-10-30 1994-05-11 Lord Corporation Thixotropic magnetorheological materials
GB9318928D0 (en) * 1993-09-13 1993-10-27 Exxon Research Engineering Co Lubricant composition containing combination of antiwear and antioxidant additives
US5412130A (en) * 1994-06-08 1995-05-02 R. T. Vanderbilt Company, Inc. Method for preparation of organic molybdenum compounds

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4957644A (en) * 1986-05-13 1990-09-18 Price John T Magnetically controllable couplings containing ferrofluids
WO1990015423A1 (en) * 1989-06-05 1990-12-13 Omni Quest Corporation Superparamagnetic liquid colloids
WO1994010694A1 (en) * 1992-10-30 1994-05-11 Lord Corporation Magnetorheological materials utilizing surface-modified particles
US5382373A (en) * 1992-10-30 1995-01-17 Lord Corporation Magnetorheological materials based on alloy particles

Also Published As

Publication number Publication date
DE69737625T2 (en) 2007-09-27
JP2000514598A (en) 2000-10-31
US5705085A (en) 1998-01-06
EP0904591B1 (en) 2007-04-18
EP0904591A1 (en) 1999-03-31
JP3893449B2 (en) 2007-03-14
DE69737625D1 (en) 2007-05-31
CA2258050A1 (en) 1997-12-18

Similar Documents

Publication Publication Date Title
US5705085A (en) Organomolybdenum-containing magnetorheological fluid
EP1027710B1 (en) Magnetorheological fluid
EP0904592B1 (en) Magnetorheological fluid
EP0755563B1 (en) Magnetorheological materials utilizing surface-modified particles
US5645752A (en) Thixotropic magnetorheological materials
EP1279175B1 (en) Magnetorheological composition
US6932917B2 (en) Magnetorheological fluids
RU2106710C1 (en) Magnetorheological material
US20020171067A1 (en) Field responsive shear thickening fluid
CA2146551A1 (en) Magnetorheological materials based on alloy particles
US20030071238A1 (en) Magnetorheological composition
US6277298B1 (en) Ferrofluid composition and process
WO2003021611A1 (en) Magnetorheological fluids with an additive package
EP1283530B1 (en) Magnetorheological fluids

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): BR CA JP KR MX

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 1997928864

Country of ref document: EP

ENP Entry into the national phase

Ref document number: 2258050

Country of ref document: CA

Ref country code: CA

Ref document number: 2258050

Kind code of ref document: A

Format of ref document f/p: F

ENP Entry into the national phase

Ref country code: JP

Ref document number: 1998 501690

Kind code of ref document: A

Format of ref document f/p: F

NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 98501690

Format of ref document f/p: F

WWP Wipo information: published in national office

Ref document number: 1997928864

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 1998501690

Format of ref document f/p: F

WWG Wipo information: grant in national office

Ref document number: 1997928864

Country of ref document: EP