Abstract: A magnetorheological composition includes a mixture of a carrier medium and a particle component disposed in the carrier medium. The particle component includes a magnetic material and a nonmagnetic material. The nonmagnetic material is present in the particle component in an amount of from about 5 to about 95 parts by volume based on 100 parts by volume of the particle component. The particle component is present in the magnetorheological composition in an amount of from about 20 to about 80 parts by volume based on 100 parts by volume of the magnetorheological composition. The magnetorheological composition has an on-state yield stress at magnetic saturation of from about 0.1 to about 100 kPa.

Abstract: A magnetorheological fluid formulation comprising magnetizable particles dispersed in carrier fluid and a thixotropic agent wherein the thixotropic agent comprises a fluorocarbon grease.

Abstract: The invention relates to magnetorheological materials comprising at least one non-magnetisable carrier medium and magnetisable particles contained therein, in addition a combination of magnetic and non-magnetic inorganic materials and/or composite particles thereof being contained.

Abstract: The invention relates to a method for producing magnetic nanoparticles which are made of metal oxide-polymer composites and are provided with an increased magnetic mobility, among other things, due the high metal oxide content and the morphological structure thereof. High-pressure homogenization has proven to be a reliable technique for producing the inventive magnetic nanoparticles. According to said technique, the components metal oxide and polymer are processed in a carrier medium. Water is used in most cases at pressures ranging from 500 bar to 1200 bar while using great shearing forces. High pressure homogenization creates a colloidally stable magnetic particle population having a diameter ranging below 200 nm while also resulting in the produced magnetic nanoparticles being provided with greater magnetic moments than the metal oxide used as an initial material at low magnetic field strengths.

Abstract: A magnetorheological formulation which comprises at least one base oil, at least one magnetizable particle, a at least one dispersant and a at least one thixotropic agent is described.

Abstract: Magnetorheological formulations, processes for preparing the same and uses therefor, the formulations comprising: (a) an ionic liquid comprising anions and cations, and (b) dispersed magnetizable particles having a mean diameter of 0.

Abstract: The present invention relates to magnetorheological elastomers comprising at least one non-magnetizable elastomeric carrier medium and magnetizable particles contained therein and also to the use thereof. In the case of MREs of this type, the mechanical properties, such as the rigidity modulus, can be changed reversibly by an applied magnetic field.

Abstract: A preparation method for synthesis of oil-based magnetic fluid is disclosed. One end of a compound with a diamino group or an organic extraction reagent is connected with oil-based material while the other end is connected with surfactant having a carboxyl group that further reacts with magnetic metal oxide nanoparticles containing surfactant to form a stable useful oil-based magnetic fluid. The present invention is applied to process wastewater with oil, organic compounds or inorganic metal ions. Under the control of the magnetic field, the floating oil on the water surface is collected. The method can also be applied to the separation as well as collection of materials in the water such as organic compounds and metals.

Abstract: An additives package for use in an MR fluid formulation is provided, as well as an MR fluid formulation containing the additives package. In one embodiment, the additives package comprises an organomolybdenum dithiocarbamate, an ashless dithiocarbamate, and a triazole compound, such as a tolutriazole compound. In another embodiment, the additives package may further include an aminic antioxidant, such as an alkylated diphenylamine. In another embodiment, the additives package is free of an organomolybdate ester. In another embodiment, the additives package consists of the organomolybdenum dithiocarbamate, the ashless dithiocarbamate, the triazole compound, and optionally the aminic antioxidant. In addition to the additives package, the magnetorheological fluid formulation comprises magnetizable particles, a carrier fluid, and a thickening agent.

Abstract: A magnetorheological fluid composition comprising a low aspect ratio magnetizable particle comprising a unimodal particle distribution and an aspect ratio less than 1.5, a high aspect ratio magnetizable particle comprising an aspect ratio greater than 1.5, and a carrier fluid.

Abstract: A magnetorheological fluid comprising magnetic-responsive particles, a thickener, an ionic thixotropic additive, and a carrier fluid wherein the carrier fluid comprises a glycol-water mixture comprising at least 50 percent by weight of a glycol compound. The thickener is preferably fumed silica and the ionic thixotropic additive is preferably one of sodium nitrite, sodium chloride, sodium acetate, and sodium benzoate.

Abstract: The present invention discloses a lipiodol-ferrofluid, and a process for preparation thereof, wherein the lipiodol-ferrofluid includes the ferrofluid including a magnetic component, ?-Fe2O3 or Fe3O4; and the lipiodol.

Abstract: A magnetic nanoparticle (22), a magnetic nanomaterial (30), assembly (30), and a method for synthsising a magnetic nanoparticle, relating to thermodynamically stable and air stable ferromagnetic nanoparticles of adjustable aspect ratio made upon decomposition of organometallic precursors in solution in the presence of a reaction gas and a mixture of organic ligands. The magnetic nanomaterial comprises magnetic nanoparticles of homogeneous size, shape, and magnetic orientation that comprises a magnetic core (24, 34) ferromagnetic at room temperature and/or operating temperatures, and a non-magnetic matrix (26, 36) encapsulating the magnetic core. This magnetic nanomaterial could be used in high frequency integrated circuit applications, such as used in wireless portable electronic devices, to enchance magnetic field confinement and improve passive component performance at MHz and GHz frequency in a variety of passive and active devices, such as transformers, on-chip signal isolation, inductors, and the like.

Abstract: An electromagnetic rheological (“EMR”) fluid (18) broadly includes a conducting medium (22) and a plurality of micronparticles (24) suspended in the medium (22). Each of the micronparticles (24) includes a magnetically permeable core (26), an electrically insulating coating (28) surrounding the core (26), and a conductive winding (30) at least partially wound around the core (26) so that the coating (28) is disposed between the winding (30) and the core (26). An apparatus (10) constructed in accordance with a preferred embodiment of the present invention broadly includes a deformable membrane (12), a pair of polar opposed plates (14 and 16) coupled to the membrane (12), the EMR fluid (18) filling the membrane (12) and being in communication with a current source (20). Current flowing through adjacent windings (30) induces magnetic fields in the corresponding micronparticles (24) that mutually draw the adjacent micronparticles (30) causing them to move together into a north pole-south pole alignment.

Abstract: A magnetorheological fluid composition comprising a carrier fluid; and a plurality of high aspect ratio magnetizable particles, wherein the aspect ratio of the high aspect ratio magnetizable particles is greater than 1.5. Optionally, the high aspect ratio magnetizable particles can have interlocking structures comprising male component and a female component. Still further, a magnetorheological fluid composition can comprise low aspect ratio magnetizable particles having the interlocking structures, wherein the aspect ratio of the low aspect ratio magnetizable particles is 1 to 1.5.

Abstract: A magnetorheological fluid composition comprising magnetizable particles in a liquid metal carrier fluid, wherein the liquid metal carrier fluid comprises a metal, a metal alloy, or a solder composition having a melting point from about ?40° C. to about 300° C., a boiling point greater than 300° C., and a viscosity greater than about 0.1 centipoise (cp) at the melting point of the liquid based metal carrier fluid. The magnetizable particles can comprise low aspect ratio magnetizable particles, high aspect magnetizable particles, or a combination thereof. Also disclosed herein are high temperature magnetorheological devices operating at temperatures greater than 100° C., and comprising the magnetorheological fluid composition.

Abstract: The present approach pertains to colloidal chemistry and methods of manufacturing magnetic fluid such as ferrofluid. In particular, the present approach is directed to methods of manufacturing magnetic fluid that is resistant to aggregation and clumping, and is more stable over time. The process according to the present approach comprises sedimentation of magnetic particles; mixing the magnetic particles with an aqueous acetic acid solution, a surface-active agent and a polarizing composition; applying pulsed magnetic fields; removing excess surface-active agents and polarizing composition; ferrite desalination; and peptization of the surface-active agent in a non-polar, dispersing fluid. Magnetic fluids made according to the process of the present approach can be used, e.g., for ferrofluidic seals, inclinometers, accelerometers, or as magnetic lubricants.

Abstract: A magnetorheological fluid composition comprising a low aspect ratio magnetizable particle comprising a unimodal particle distribution and an aspect ratio less than 1.5, a high aspect ratio magnetizable particle comprising an aspect ratio greater than 1.5, and a carrier fluid.

Abstract: The present invention relates in one embodiment to magnetorheological fluids utilized in prosthetic joints in general and, in particular, to magnetorheological fluids utilized in controllable braking systems for prosthetic knee joints. Preferred magnetorheological fluids of the present invention comprises polarizable iron particles, a carrier fluid, and optionally an additive. Preferred additives include, but are not limited to functionalized carrier fluids as well as derivatized fluoropolymers. Preferred carrier fluids include, but are not limited, to perfluorinated polyethers.

Abstract: Magnetorheological materials having a supramolecular polymer gel as a component of the carrier are disclosed. Useful supramolecular polymers for gels include those having terpyridine ligands which can participate in metal coordination bonding. The magnetizable particles of magnetorheological materials can have supramolecular surfactant-polymer coatings.

Abstract: The present approach pertains to colloidal chemistry and methods of manufacturing magnetic fluid such as ferrofluid. In particular, the present approach is directed to methods of manufacturing magnetic fluid that is resistant to aggregation and clumping, and is more stable over time. The process according to the present approach comprises sedimentation of magnetic particles; mixing the magnetic particles with an aqueous acetic acid solution, a surface-active agent and a polarizing composition; applying pulsed magnetic fields; removing excess surface-active agents and polarizing composition; ferrite desalination; and peptization of the surface-active agent in a non-polar, dispersing fluid. Magnetic fluids made according to the process of the present approach can be used, e.g., for ferrofluidic seals, inclinometers, accelerometers, or as magnetic lubricants.

Abstract: The present invention discloses a Lipiodol-ferrofluid, and a process for preparation thereof, wherein the Lipiodol-ferrofluid includes the ferrofluid including a magnetic component, ?-Fe2O3 or Fe3O4; and the Lipiodol.

Abstract: The invention provides a magnetorheological device employing narrow design gap and containing a magnetic-responsive composition exhibiting reduced off-state forces and good performance. Specifically, this invention is directed to a magnetorheological device of defined gap, and employing a magnetic-responsive composition characterized by comprising non-sperical magnetic-responsive particles of average number diameter distribution (d50) from 6 to 100 microns and at least one friction-reducing additive that reduces the interparticle friction between the magnetic-responsive particles.

Abstract: The invention in some embodiments relates to systems and methods of loading fluid in a prosthetic knee. A vacuum fill technique is utilized in one embodiment to load magnetorheological fluid within small gaps in a chamber of a prosthetic knee. Advantageously, this allows for an efficient loading scheme thereby desirably allowing for faster manufacturing speed. Another advantage is that the magnetorheological fluid is substantially uniformly distributed within the small gaps thereby desirably providing consistent production.

Abstract: The present invention relates in one embodiment to magnetorheological fluids utilized in prosthetic joints in general and, in particular, to magnetorheological fluids utilized in controllable braking systems for prosthetic knee joints. Preferred magnetorheological fluids of the present invention comprises polarizable iron particles, a carrier fluid, and optionally an additive. Preferred additives include, but are not limited to functionalized carrier fluids as well as derivatized fluoropolymers. Preferred carrier fluids include, but are not limited, to perfluorinated polyethers.

Abstract: What is disclosed is a magnetorheological fluid useful for incorporating within the working gap of magnetorheologically controllable linear or rotary devices. The MR fluid includes a carrier fluid component and a magnetic responsive particle component characterized by D10 of 2 ?m up to and including a D10 of 5 ?m, a D50 of 8 ?m up to and including D50 of 15 ?m; a D90 of 25 ?m to and including a D90 of 40 ?m; and further characterized by least squares regression (R2) particles size against log normal cumulative volume percent of greater than or equal to 0.77. Optional preferred additives included therewith include thixotropic agent or viscosity modifier, dispersant or surfactant, antioxidant, corrosion inhibitor, and one or more lubricants.

Abstract: A MR fluid formulation based upon a silicone liquid vehicle thickened with a treated fumed metal oxide and doped with one or more chemicals having hydrogen-bonding capability for use with natural rubber mounts. The MR fluid is resistant to settling of the magnetizable particles upon contact of the fluid with natural rubber. In one exemplary embodiment, the doping chemical is one or a combination of propylene glycol and a bifunctional ethoxylated amine.

Abstract: The invention provides a magnetorheological composition having reduced off-state forces and good performance. Specifically, this invention is directed to a magnetorheological composition that may comprise non-sperical magnetic-responsive particles and at least one friction-reducing additive that reduces the interparticle friction between the magnetic-responsive particles.

Abstract: An element-modified ferrofluid comprising a base oil, a plurality of magnetic particles covered with at least one surfactant, and an elemental modifier. The elemental modifier is a metal, a metal mixture, an alloy, or a nonmetal.

Abstract: Carrier assemblies, planarizing machines with carrier assemblies, and methods for mechanical and/or chemical-mechanical planarization of micro-device workpieces are disclosed herein. In one embodiment, the carrier assembly includes a head having a chamber, a magnetic field source carried by the head, and a fluid with magnetic elements in the chamber. The magnetic field source has a first member that induces a magnetic field in the head. The fluid and/or the magnetic elements move within the chamber under the influence of the magnetic field source to exert a force against a portion of the micro-device workpiece. In a further aspect of this embodiment, the carrier assembly includes a flexible member in the chamber. The magnetic field source can be any device that induces a magnetic field, such as a permanent magnet, an electromagnet, or an electrically conductive coil.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including 10 to 14 wt % of a hydrocarbon-based liquid, 86 to 90 wt % of bimodal magnetizable particles, and 0.05 to 0.5 wt % fumed silica.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including a liquid, magnetizable particles, and a molybdenum-amine complex.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including a liquid, magnetizable particles, a stearate and a thiophosphate.

Abstract: A magnetic dispersion medium is used in a magnetic writing screen toy. The dispersion medium is attracted to the underside of the screen when a magnetic tipped pen is passed over the upper surface of the screen. A user can create drawings and figures. The dispersion medium is non-toxic, creates lines having good contrast and can be easily erased without permanently forming black marks on the screen. The dispersion medium works well in temperature ranges between ?20° C. to 45° C.

Abstract: The present invention relates to a magnetorheological fluid composition and a process for preparing the same, which has excellent magnetorheological properties. The fluid composition exhibits change in rheological characteristics in the presence of an external magnetic field. Further, the magnetorheological characteristics of the fluid composition can be optimised for the improved magnetic sensitivity to external magnetic field and negligible magnetic retentivity after removal of the external magnetic field. The sensitivity of the fluid to external magnetic field can be varied by varying the pure iron content of the magnetic sensitive particles composition while, the magnetic retentivity of the fluid (after removal of external magnetic field) can be varied by varying the ferrite alloy content of the same. The fluid composition utilises a magnetic sensitive particles stabiliser or surfactant, which is synthesised from the carrier fluid used in the fluid composition.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including 10 to 14 wt % of a hydrocarbon-based liquid, 86 to 90 wt % of bimodal magnetizable particles, 0.05 to 0.5 wt % fumed silica, and an additive package including a paraffin oil, a phenol and a sulfide.

Abstract: A magnetorheological fluid formulation comprising magnetizable particles dispersed in a non-aqueous, glycol-based liquid vehicle thickened effectively by either a fully treated fumed silica or an organoclay. The surface treated fumed silica is fully treated with a treatment molecule having a molecular weight of at least about 200. The organoclay comprises sepiolite and/or palygorskite. The glycol-based fluid advantageously consists essentially of propylene glycol and optionally ethylene glycol.

Abstract: A durable magnetorheological fluid for use in a vibration dampening device is described. The MR fluid includes magnetizable particles having a particle size less than about 25 microns, a carrier fluid, a thixotropic agent, and a lubricative additive. The carrier fluid includes a polyalphaolefin and a plasticizer. The lubricative additive has a particle size equal to or less than 10 microns such that the ability of the additive to lubricate the magnetizable particles is optimized. The lubricative additive includes at least one of polytetrafluoroethylene, graphite, and molybdenum disulfide.

Abstract: There is disclosed a magnetic fluid medium which comprises a plurality of ferro- or ferri-magnetic particles, each of which particles has a largest dimension no greater than 100 nm, said particles having been prepared by a process which includes a step in which the particles are formed within an organic macromolecular shell.

Abstract: The present invention relates in one embodiment to magnetorheological fluids utilized in prosthetic joints in general and, in particular, to magnetorheological fluids utilized in controllable braking systems for prosthetic knee joints. Preferred magnetorheological fluids of the present invention comprises polarizable iron particles, a carrier fluid, and optionally an additive. Preferred additives include, but are not limited to functionalized carrier fluids as well as derivatized fluoropolymers. Preferred carrier fluids include, but are not limited, to perfluorinated polyethers.

Abstract: The subject invention provides a magnetorheological (MR) composition having improved resistance to oxidation and increased dispersability in a carrier fluid. The composition includes a plurality of metal particles and a surfactant including a hydrocarbon with at least one of a hydroxyl, a carbonyl, and an amine group bonded to the hydrocarbon for reacting with the metal particles. The surfactant is present in an amount such that from about 1% to about 20% of the amount of the surfactant is adsorbed to the metal particles. The surfactant is reacted with the metal particles such that about 75% to about 100% of a maximum amount of the surfactant adsorbs to the metal particles for improving the resistance of the metal particles to oxidation and for increasing the dispersability of the magnetorheological composition in the carrier fluid. The MR composition according to the subject invention is utilized in a magnetorheological (MR) fluid.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including 10 to 14 wt % of a hydrocarbon-based liquid, 86 to 90 wt % of bimodal magnetizable particles, and 0.05 to 0.5 wt % fumed silica.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including a liquid, magnetizable particles, and a molybdenum-amine complex.

Abstract: An element-modified ferrofluid comprising a base oil, a plurality of magnetic particles covered with at least one surfactant, and an elemental modifier. The elemental modifier is a metal, a metal mixture, an alloy, or a nonmetal.

Abstract: An MR fluid formulation comprising water-atomized iron powder dispersed in a liquid vehicle, wherein the atomized iron powder contributes to a higher magnetic effect, a lower viscosity and suitability for high temperature applications. The magnetizable particles are prepared by controlled water atomization and comprise iron having a passivating oxide surface layer. The passivating oxide surface layer advantageously comprises iron oxide and at least one alloying metal oxide, such as manganese oxide. Advantageously, the particles have a grain size of at least 4 &mgr;m and a mean diameter in the range of about 8-25 &mgr;m. The liquid vehicle advantageously comprises a mixture of at least two liquid components of different surface functionality and an organoclay stabilization mixture in which at least one organoclay is selected for each liquid vehicle component.

Abstract: The present invention is directed to a stabilized dispersion magnetorheological fluid comprising a magnetic particle, a dispersive medium and a dispersing agent wherein said dispersing agent is a polyether containing a polymer unit represented by the following general formula (1): in the formula, R1 represents a hydrogen atom or a hydrocarbon group of 1 to 22 carbon atoms; R2 represents a hydrogen atom, a hydrocarbon group of 1 to 22 carbon atoms which may optionally have a substituent, or —(AO)m-R3; R3 represents a hydrocarbon group of 1 to 22 carbon atoms which may optionally have a substituent; A represents an alkylene group of 1 to 3 carbon atoms; m represents an integer of 1 to 50; and A groups which number m may be the same or different.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including a liquid, magnetizable particles, a stearate and a thiophosphate.

Abstract: The invention provides a magnetorheological composition having reduced off-state forces and good performance. Specifically, this invention is directed to a magnetorheological composition that may comprise non-sperical magnetic-responsive particles and at least one friction-reducing additive that reduces the interparticle friction between the magnetic-responsive particles.

Abstract: One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including a liquid, magnetizable particles, a stearate and a thiophosphate.

Abstract: A magnetorheological fluid formulation comprising magnetizable particles dispersed in a non-aqueous, glycol-based liquid vehicle thickened effectively by either a fully treated fumed silica or an organoclay. The surface treated fumed silica is fully treated with a treatment molecule having a molecular weight of at least about 200. The organoclay comprises sepiolite and/or palygorskite. The glycol-based fluid advantageously consists essentially of propylene glycol and optionally ethylene glycol.