|
When myriad of
ultra microscopic dipolar permanent magnets are colloidally
dispersed in any nonmagnetic liquid matrix such as water or oil,
a magnetic fluid is formed. Or in other wards, magnetic fluid is
a stable colloidal dispersion of ferri / ferro magnetic
particles of nano size in liquid carrier. It is stabilized
either by coating hydrocarbon chain or providing an
electrostatic charge on the particles. It is known as surfacted
or ionic magnetic fluid. The number density of magnetic
particles in a magnetic fluid can reach up to 1023 particles/m3.
Under normal condition & absence of external magnetic field,
magnetic fluid becomes thermodynamically unstable. Hence
magnetic dipole moment of each particle is randomly oriented and
there is no resultant moment observed. So under normal condition
& absence of external magnetic field, magnetic fluid behaves
just like an ordinary fluid.
When magnetic fluid is placed under the influence of an external
magnetic field, the dipole moment of each particle tends to
align in the direction of an external magnetic field. So there
is a large magnetic moment induced inside the medium. Therefore
the fluid has net resultant magnetization. So under the
influence of external magnetic field, the fluid exhibit several
apparently looking like magical phenomena like defying gravity,
levitation of non-magnetic object immersed in the fluid,
spontaneous formation of spike, self levitation of magnets (in
absence of other externally applied magnetic field. When it
subjected to an external magnetic field, it exhibits large
magnetization and when the field removed, the magnetic fluid
instantaneously attains its zero magnetic state.
|
Properties
of Standard Magnetic Fluid. |
|
Carrier |
Saturation Magnetization |
Ferrite Particles |
Viscosity |
Possible use |
|
Water |
50 to 150 Gauss |
Magnetite |
»
5 cp |
Domain detection |
|
Hydrocarbon |
50 to 500 Gauss |
Magnetite |
» 2 cp |
Domain detection,
sensors |
|
Diester |
300 Gauss |
Magnetite |
»
100 to 1500 cp |
Separators, dampers, seals,
loud speaker |
|
Diester |
250 Gauss |
Mn-Zn ferrite |
< 100 cp |
Temperature sensitive |
|
|
Application
of Magnetic Fluid.. |
|
Mechanical Engineering |
Chemical Engineering |
Optics |
Space Science |
Biotechnology |
|
Pumping |
Ink-jet
printer |
Spatial
filters |
Satellite
dampers |
Targeted drug delivery
|
|
Switches |
Gas valve |
Optical
valves |
Actuator |
enzyme separation |
|
Dampers |
separators |
Black &
White display |
|
cell binding |
|
We can also supply nanomagnets covered with polypeptides (e.g.
bovine serum albumin of polysaccharides such as dextran. Special
magnetic fluids are available on request. Please specify the
purpose for which it to be used. Also mention environmental
conditions like temperature, pressure etc.
Temperature Sensitive Magnetic Fluid:
Ferro fluids usually available in market contain magnetite as
nanoparticles; such fluids have high Curie temperature and low
pyromagnetic coefficient. We have synthesized fluids which have
low Curie temperature (<70 °c) and have high pyromagnetic
coefficient. These fluids may find application in energy
conversion devices, transformer oil cooling etc. |
