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Transcript
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
• 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been replaced by more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
• 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
• Can stick to a magnet.
• Will take on the 3dimensional 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
•
•
•
•
Lithographic (currency)
Sealing Technology
Bio-Medical
Loud speakers
Lithographic (currency)
• Magnetic inks are
printed onto paper
money and used for bar
codes for identification
purposes.
• Makes counterfeiting
more difficult.
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
• 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
• 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.
Our Ferrofluid Pictures
Cool Ferrofluid Pictures
References
• http://www.carolina.com/physics/aboutferro.asp
• http://www.ferrotec.com/usa/ferrofluid_technology_o
verview.htm
• http://www.zarm.unibremen.de/2forschung/ferro/basic_info/applic/applic.
htm
• Journal of Chemical Education, Volume 76, No. 7, July
1999. http://JChemEd.chem.wisc.edu