10-04-2017, 07:53 PM
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Ferrofluids
Description
Developed by NASA??
Composed of magnetite, hematite, or other compound containing iron.
Tiny iron particles covered with liquid coating.
Surfactant added to water or oil, which gives liquid properties.
Has more than one state of matter (colloidal suspensions).
Lose their magnetic properties at high temperatures, known as the curie temperature.
How they work?
Prepared by combining appropriate amounts of an Fe(II) salt and an Fe(II) salt in basic solution.
Particles of magnetite must remain small to remain suspended in liquid medium.
To keep them small a surfactant is added to the liquid medium.
Surfactant is a long-chain hydrocarbon that is attracted to the surface of magnetite particle.
Surfactant is used as a repellent cushion and prevent approach of other magnetite particles.
Applications
Rotating Shaft seals (liquid O-ring)
Magnetic particles form a barrier which prevents debris from entering the interior.
Performance of loudspeakers
Provides heat conduction from voice coil to the surrounding assembly providing better sound quality .
Biomedical applications
Researchers attempting to design ferrofluids that can carry medications to specific locations in the body using magnetic fields.