 Ferrofluid on glass, with a magnet underneath. A ferrofluid (from the Latin ferrum, meaning iron) is a liquid which becomes strongly polarised in the presence of a magnetic field. Image File history File links Download high-resolution version (1587x1190, 440 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
Image File history File links Download high-resolution version (1587x1190, 440 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
Current (I) flowing through a wire produces a magnetic field () around the wire. ...
Ferrofluids are composed of nanoscale ferromagnetic particles suspended in a carrier fluid, usually an organic solvent or water. The ferromagnetic nano-particles are coated with a surfactant to prevent their agglomeration (due to van der Waals and magnetic forces). Although the name may suggest otherwise, ferrofluids do not display ferromagnetism, since they do not retain magnetisation in the absence of an externally applied field. In fact, ferrofluids display paramagnetism, and are often referred as being "superparamagnetic" due to their large magnetic susceptibility. Truly ferromagnetic fluids are difficult to create at present, requiring high temperatures and electromagnetic levitation. [1] A mite next to a gear set produced using MEMS, the precursor to nanotechnology. ...
Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ...
A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of the magnitude of the applied stress. ...
Surfactants are wetting agents that lower the surface tension of a liquid, allowing easier spreading, and lower the interfacial tension between two liquids. ...
In chemistry, the term van der Waals force originally referred to all forms of intermolecular forces; however, in modern usage it tends to refer to intermolecular forces that deal with forces due to the polarization of molecules. ...
Ferromagnetism is the phenomenon by which materials, such as iron, in an external magnetic field become magnetized and remain magnetized for a period after the material is no longer in the field. ...
Simple Illustration of a paramagnetic probe made up from miniature magnets. ...
In electrical engineering, the magnetic susceptibility is the degree of magnetization of a material in response to an applied magnetic field. ...
Description
 A ferrofluid, influenced by a magnet underneath. Ferrofluids comprise microscopic ferromagnetic nano-particles, usually magnetite, hematite or some other compound containing Iron. The nano-particles are typically of order 10nm. This is small enough for thermal agitation to disperse them evenly within a carrier fluid, and for them to contribute to the overall magnetic response of the fluid. This is analogous to the way that the ions in an aqueous paramagnetic salt solution (such as an aqueous solution of copper sulphate or manganese chloride) make the solution paramagnetic. Image File history File linksMetadata Download high resolution version (1600x1200, 404 KB) Description: A Ferrofluid, influenced by an underneath magnet. ...
Image File history File linksMetadata Download high resolution version (1600x1200, 404 KB) Description: A Ferrofluid, influenced by an underneath magnet. ...
// Headline text Magnetite is a ferrimagnetic mineral form of iron(II,III) oxide, with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. ...
Hematite (AE) or haematite (BE) is the mineral form of Iron(III) oxide, (Fe2O3), one of several iron oxides. ...
Paramagnetism is the tendency of the atomic magnetic dipoles, due to quantum-mechanical spin, in a material that is otherwise non-magnetic to align with an external magnetic field. ...
True ferrofluids are stable. This means that the solid particles do not agglomerate or phase separate even in extremely strong magnetic fields. However, the surfactant tends to break down over time (a few years), and eventually the nano-particles will agglomerate, and they will separate out and no longer contribute to the fluid's magnetic response. The term magnetorheological fluid (MRF) refers to liquids similar to ferrofluids (FF) that solidify in the presence of a magnetic field. Magnetorheological fluids have micrometre scale magnetic particles that are 1–3 orders of magnitude larger than those of ferrofluids. A ferrofluid is a specific type of liquid which responds to a magnetic field. ...
A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the size of a droplet of mist or fog. ...
Normal-field instability When a paramagnetic fluid is subjected to a sufficiently strong vertical magnetic field, the surface spontaneously forms a regular pattern of corrugations. This effect, known as the normal-field instability, is truly remarkable. The formation of the corrugations increases the surface free energy and the gravitational energy of the liquid, but reduces the magnetic energy. The corrugations will only form above a critical magnetic field, when the reduction in magnetic energy outweighs the increase in surface and gravitation energy terms. Ferrofluids have an exceptionally high magnetic susceptibility and the critical magnetic field for the onset of the corrugations can be realised by a small bar magnet ( see figure ). Image File history File linksMetadata Download high-resolution version (1398x960, 755 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Ferrofluid User:GeeJo/Gallery Wikipedia:Featured pictures candidates/July-2006 Wikipedia:Featured picture candidates/Ferrofluid in magnetic field...
Image File history File linksMetadata Download high-resolution version (1398x960, 755 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Ferrofluid User:GeeJo/Gallery Wikipedia:Featured pictures candidates/July-2006 Wikipedia:Featured picture candidates/Ferrofluid in magnetic field...
Current (I) flowing through a wire produces a magnetic field () around the wire. ...
Neodymium magnet on a bracket from a hard drive A neodymium magnet or NIB magnet (also, but less specifically, called a rare-earth magnet) is a powerful magnet made of a combination of neodymium, iron, and boron — Nd2Fe14B. They have replaced marginally weaker and significantly more heat-resistant samarium-cobalt...
Common ferrofluid surfactants Ferrofluids often contain surfactants including, but not limited to: These surfactants serve to decrease the rate of ferroparticle settling, of which a high rate is an unfavorable characteristic of ferrofluids. The ideal ferrofluid would never settle in the absence of real-world friction. Surfactant-aided prolonged settling is typically achieved in one of two ways. In the case of the addition of soy lecithin, the surfactant particles are nanospheres and prolong the onset of settling via Brownian motion. In the case of oleic acid and other micelle surfactants, the effective diameter of each ferroparticle is increased by the attachment of micelle molecules to each ferroparticle, thereby increasing particle diameter and making fluid remixing (particle redispersion) occur far faster and with less effort. Oleic acid is a monounsaturated omega-9 fatty acid found in various animal and vegetable sources. ...
Tetramethylammonium hydroxide (TMAH) is a quaternary ammonium salt with the molecular formula (CH3)4NOH. It is used as an anisotropic etchant of silicon. ...
Citric acid is a weak organic acid found in citrus fruits. ...
Lecithin, also known as Phosphatidylcholine Lecithin is usually used as synonym for phosphatidylcholine, a phospholipid which is the major component of a phosphatide fraction which may be isolated from either egg yolk (in Greek lekithos - λεκιθος) or soy beans from which it is mechanically or chemically extracted using hexane. ...
Surfactants are wetting agents that lower the surface tension of a liquid, allowing easier spreading, and lower the interfacial tension between two liquids. ...
Three different views of Brownian motion, with 32 steps, 256 steps, and 2048 steps denoted by progressively lighter colors. ...
Schematic of a micelle. ...
While surfactants are useful in prolonging the settling rate in ferrofluids, they also prove detrimental to the fluid's magnetic properties (specifically, the fluid's magnetic saturation), which is commonly a parameter which users wish to maximize (this is typically more of a concern when dealing with magnetorheological fluids). Whether or not the surfactant is nanosphere-based or micelle-based, the addition of surfactants (or any other foreign particles) decreases the packing density of the ferroparticles while in its activated state, thus decreasing the fluids on-state viscosity, resulting in a "softer" activated fluid. While the on-state viscosity (the "hardness" of the activated fluid) is less of a concern for some ferrofluid applications, it is a primary fluid property for the majority of their commercial and industrial applications and therefore a compromise must be met when considering on-state viscosity vs. the settling rate of a ferrofluid. A magnetorheological fluid is a type of smart fluid. ...
Applications
 Ferrofluid under the influence of a strong vertical magnetic field. Image File history File links Download high-resolution version (2048x1536, 369 KB) Ferrofluid, a paramagnetic fluid composed of nanoscale ferromagnetic particles suspended in a carrier fluid, was placed onto a glass plate. ...
Image File history File links Download high-resolution version (2048x1536, 369 KB) Ferrofluid, a paramagnetic fluid composed of nanoscale ferromagnetic particles suspended in a carrier fluid, was placed onto a glass plate. ...
Electronic devices Matsushita Electric Industry produced a printer capable of printing 5 pages per minute using a ferrofluid ink. Logo for the Panasonic brand Matsushita Electric Industrial Co. ...
Look up printer in Wiktionary, the free dictionary. ...
An ink is a liquid containing various pigments and/or dyes used for colouring a surface to render an image or text. ...
Ferrofluids are similarly used to form liquid seals (ferrofluidic seals) around the spinning drive shafts in hard disks. The rotating shaft is surrounded by magnets. A small amount of ferrofluid, placed in the gap between the magnet and the shaft, will be held in place by its attraction to the magnet. The fluid of magnetic particles forms a barrier which prevents debris from entering the interior of the hard drive. However, the ferrofluid is still similar enough in properties to a true liquid that it will not interfere with the spinning of the shaft. Seal or SEAL can refer to: Seal, a device used to produce an official stamp as a symbol of authority. ...
A ferofluidic magnetic seal is a sealing mechanism used in rotating equipment to contain a fluid by means of a physical barrier in the form of a ferrofluid. ...
Typical hard drives of the mid-1990s. ...
Another common use of ferrofluids is as a liquid coolant. One commercial application for this usage is in megaphones and loudspeakers. A ferrofluid is put in the space between the permanent magnet and the voice coil of a speaker. Just as in the hard drive, the permanent magnet will hold the ferrofluid in place, keeping it in contact with the voice coil. The metal content of the ferrofluid acts as a heat conductor, transmitting the heat of the voice coil’s vibration out of the speaker to prevent damage. A megaphone, with a three-inch lighter to scale. ...
A loudspeaker is a device which converts an electrical signal into sound. ...
A voice coil is the coil of wire attached to the apex of the moving cone of a loudspeaker. ...
Look up Speaker in Wiktionary, the free dictionary. ...
Mechanical engineering Ferrofluids have friction-reducing capabilities. If applied to the surface of a strong enough magnet, such as one made of neodymium, it can glide across smooth surfaces with minimal resistance. General Name, Symbol, Number neodymium, Nd, 60 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white, yellowish tinge Atomic mass 144. ...
Magnetorheological fluid-based dampers of various applications are being, and have been, developed. These dampers are mainly used in heavy industry with applications such as heavy motor dampening, operator seat/cab dampening in construction vehicles, and more. A ferrofluid is a specific type of liquid which responds to a magnetic field. ...
As of 2006, materials scientists and mechanical engineers are collaborating to develop stand-alone seismic dampers which, when positioned anywhere within a building, will operate within the building's resonant frequency, absorbing detrimental shock waves and oscillations within the structure, giving these dampers the ability to make any building earthquake-proof, or at least earthquake-resistant. Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...
This article is about resonance in physics. ...
Shock Waves is a horror movie from 1977 directed by Ken Wiederhorn. ...
Defense The United States Air Force introduced a Radar Absorbent Material (RAM) paint made from both ferrofluidic and non-magnetic substances. By reducing the reflection of electromagnetic waves, this material helps to reduce the Radar Cross Section of aircraft. Aircraft of the 379th Air Expeditionary Wing and coalition counterparts stationed together at Al Udeid Air Base, Qatar, in southwest Asia, fly over the desert. ...
Radar absorbing paint, or RAM coating, is used in Stealth technology. ...
Spheres reflecting the floor and each other. ...
Electromagnetic radiation or EM radiation is a combination (cross product) of oscillating electric and magnetic fields perpendicular to each other, moving through space as a wave, effectively transporting energy and momentum. ...
Radar cross section (RCS) is a description of how an object reflects an incident electromagnetic wave. ...
An Airbus A380, currently the worlds largest passenger airliner An aircraft is any vehicle or craft capable of atmospheric flight. ...
Aerospace NASA has experimented using ferrofluids in a closed loop as the basis for a spacecraft's attitude control system. A magnetic field is applied to a loop of ferrofluid to change the angular momentum and influence the rotation of the spacecraft. // In the context of spacecraft, attitude control is control of the angular position and rotation of the spacecraft, either relative to the object that it is orbiting, or relative to the celestial sphere. ...
Current (I) flowing through a wire produces a magnetic field () around the wire. ...
This gyroscope remains upright while spinning due to its angular momentum. ...
Optics QED Technologies has developed a magnetorheological fluid-based optical polishing method which has proven to be highly precise. QED's polishing method was used in the construction of the Hubble Space Telescope's corrective lens. A ferrofluid is a specific type of liquid which responds to a magnetic field. ...
The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ...
Measurement Ferrofluids have numerous optical applications due to their refractive properties; that is, each grain, a micromagnet, reflects light. These applications include measuring specific viscosity of a liquid placed between a polarizer and an analyzer, illuminated by a helium-neon laser. See also list of optical topics. ...
Refraction in a Perspex (acrylic) block. ...
Iron filings in a magnetic field generated by a bar magnet Dylan Leibel has a 12 inch cock and screws a new girl every week!!! 8=======D Magnets are materials that produce a magnetic field of their own. ...
In electrodynamics, polarization (also spelled polarisation) is the property of electromagnetic waves, such as light, that describes the direction of their transverse electric field. ...
Wikipedia does not yet have an article with this exact name. ...
General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ...
General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ...
A laser (acronym for light amplification by stimulated emission of radiation) is an optical source that emits photons in a coherent beam. ...
Medicine In medicine, a compatible ferrofluid can be used for cancer detection. There is also much experimentation with the use of ferrofluids to remove tumors. The ferrofluid would be forced into the tumor and then subjected to a quickly varying magnetic field. This would create friction, yielding heat, due to the movement of the ferrofluid inside the tumor which could destroy the tumor. medicines, see medication and pharmacology. ...
The term compatibility has the following meanings: In telecommunication, the capability of two or more items or components of equipment or material to exist or function in the same system or environment without mutual interference. ...
Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ...
Heat transfer An external magnetic field imposed on a ferrofluid with varying susceptibility, e.g., due to a temperature gradient, results in a nonuniform magnetic body force, which leads to a form of heat transfer called thermomagnetic convection. This form of heat transfer can be useful when conventional convection heat transfer is inadequate, e.g., in miniature microscale devices or under reduced gravity conditions. In thermal physics, heat transfer is the passage of thermal energy from a hot to a cold object. ...
Ferrofluids can be used to transfer heat, since heat and mass transport in such magnetic fluids can be controlled using an external magnetic field. ...
Ferrofluids are commonly used in loudspeakers to sink heat between the voice coil and the magnet assembly, and to passively damp the movement of the cone. They reside in what would normally be the air gap around the voice coil, held in place by the speaker's magnet. Since ferrofluids are paramagnetic, they obey Curie's law, thus become less magnetic at higher temperatures. A strong magnet placed near the voice coil (which produces heat) will always attract colder ferrofluid towards it more than warmer ferrofluid thus forcing the heated ferrofluid away, towards the heat sink. This is an efficient cooling method which requires no additional energy input. A 3. ...
Automotive If the shock absorbers of a vehicle' suspension are filled with ferrofluid instead of plain oil, and the whole device surrounded with an electromagnet, the viscosity of the fluid (and hence the amount of damping provided by the shock absorber) can be varied depending on driver preference or the weight being carried by the vehicle - or it may be dynamically varied in order to provide stability control. The MagneRide magnetic ride control or active suspension is one such system which permits the damping factor to be adjusted once every millisecond in response to conditions. As of 2007, BMW manufactures cars using their own proprietary version of this device, while GM (the first auto manufacturer to do so), Audi, and Ferrari offer the MagneRide on various models. Gasfilled Shock absorber. ...
The front suspension components of a Ford Model T. Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. ...
An electromagnet is a type of magnet in which the magnetic field is produced by a flow of electric current. ...
Damping is any effect, either deliberately engendered or inherent to a system, that tends to reduce the amplitude of oscillations of an oscillatory system. ...
MagneRide is a semi-active suspension technology from Delphi Corporation. ...
General Motors and other automotive companies are seeking to develop a magnetorheological fluid based clutch system for push-button four wheel drive systems. This clutch system would use electromagnets to solidify the fluid which would lock the driveshaft into the drive train. General Motors Corporation, also known as GM, is the worlds largest car manufacturer. ...
A ferrofluid is a specific type of liquid which responds to a magnetic field. ...
An electromagnet is a type of magnet in which the magnetic field is induced by a flow of electric current. ...
Cardan driveshaft with universal joints A driveshaft or driving shaft or Cardan shaft is a mechanical device for transferring power from the engine or motor to the point where useful work is applied. ...
The drive train of a vehicle is its engine, transmission, suspension (mechanical), and final drive (wheels, caterpillar track, propeller, etc). ...
See also Wikimedia Commons has media related to: Image File history File links Commons-logo. ...
A smart fluid is a fluid whose properties (most commonly the viscosity) can be changed by applying an electric field or a magnetic field. ...
A ferrofluid is a specific type of liquid which responds to a magnetic field. ...
Electrorheological (ER) fluids are suspensions of extremely fine particles (up to 50 microns) in non-conducting fluids. ...
Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics) is the academic discipline which studies the dynamics of electrically conducting fluids. ...
A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ...
Fluid mechanics is the subdiscipline of continuum mechanics that studies fluids, that is, liquids and gases. ...
Continuum mechanics is a branch of physics (specifically mechanics) that deals with continuous matter, including both solids and fluids (i. ...
External links
Preparation instructions - How to make magnetic fluid — Anne Marie Helmenstine, Ph.D.
- FerroFluid Synthesis — Sci-Spot.com
- Berger, Patricia; Nicholas B. Adelman, Katie J. Beckman, Dean J. Campbell, et al (July 1999). "Preparation and properties of an aqueous ferrofluid". Journal of Chemical Education 76 (7): pp. 943-948. ISSN 00219584. Retrieved on 2007-01-02.
- Interdisciplinary education group: Ferrofluids (contains videos and a lab for synthesis of ferrofluid)
- Synthesis of an Aqueous Ferrofluid — instructions in DOC and PDF format
ISSN, or International Standard Serial Number, is the unique eight-digit number applied to a periodical publication including electronic serials. ...
2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ...
January 2 is the second day of the year in the Gregorian calendar. ...
Look up doc in Wiktionary, the free dictionary. ...
PDF is an abbreviation with several meanings: Portable Document Format Post-doctoral fellowship Probability density function There also is an electronic design automation company named PDF Solutions. ...
References - ^ First observation of ferromagnetism and ferromagnetic domains in a liquid metal
- Ferrohydrodynamics (1985), Ronald. E. Rosensweig. The usual starting reference for learning the details of ferrofluids.
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