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Ferrofluids. Charles Wolfe, Newell Jensen, Jonathan Hogander and Seth McDonough. What Is Ferrofluid?. It’s a liquid magnet. A fluid in which fine particles of iron, magnetite or cobalt are suspended in an oil surfactant. History of Ferrofliuds.

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ferrofluids

Ferrofluids

Charles Wolfe, Newell Jensen, Jonathan Hogander and Seth McDonough

what is ferrofluid
What Is Ferrofluid?
  • It’s a liquid magnet.
  • A fluid in which fine particles of iron, magnetite or cobalt are suspended in an oil surfactant.
history of ferrofliuds
History of Ferrofliuds
  • In the 1960’s Stephen Pappell at NASA first developed ferrofluids as a method for controlling fluids in space.
  • Magnets and/or magnetic fields were used to control this magnetic fluid.
  • Currently applications of Ferrofluids in space have been replaced by more economical fluids.
mechanics of ferrofluids
Mechanics of Ferrofluids
  • Small magnetite particles are held in colloidal suspension due to interparticle electrostatic repulsion. This is brought about by the attraction of the hydroxide anion to the magnetite particles which in turn attract the positive tetrmethyl-ammonium cations.
unique properties of ferrofluids
Unique Properties of Ferrofluids
  • Can stick to a magnet.
  • Will take on the 3-dimensional shape of the magnetic field that passes through it.
  • Changes its density in proportion to the strength of the magnetic field that’s applied to it.
applications
Applications
  • Lithographic (currency)
  • Sealing Technology
  • Bio-Medical
  • Loud speakers
lithographic currency
Lithographic (currency)
  • Magnetic inks are printed onto paper money and used for bar codes for identification purposes.
  • Makes counterfeiting more difficult.
sealing technology
Sealing Technology
  • Used for bearing seals in hard drives. The fluid is held in place by magnets creating a magnetic seal (o-ring) for high speed rotation.
bio medical
Bio-Medical
  • Have been used in medicine since the 1960’s.
  • Magnetically position organs during abdominal or brain surgery.
  • Attaching drugs to the surface of magnetic particles and use magnetic fields to hold the drug at the site where it is needed.
loud speakers
Loud Speakers
  • Most common application. Helps to cool loud speakers by filling in the gap of the permanent magnet in speakers.
  • Cooling occurs due to convection like affect of the fluctuating magnetic field in the speaker.
references
References
  • http://www.carolina.com/physics/aboutferro.asp
  • http://www.ferrotec.com/usa/ferrofluid_technology_overview.htm
  • http://www.zarm.uni-bremen.de/2forschung/ferro/basic_info/applic/applic.htm
  • Journal of Chemical Education, Volume 76, No. 7, July 1999. http://JChemEd.chem.wisc.edu