What are ferrofluids used for?
What are ferrofluids used for?
Ferrofluid is used in rotary seals in computer hard drives and other rotating shaft motors, and in loudspeakers to dampen vibrations. In medicine, ferrofluid is used as a contrast agent for magnetic resonance imaging (MRI).
How do you make ferrofluids?
Pour a bit of vegetable oil into a shallow dish, just enough to make a thin film across the bottom. Pour iron filings into the oil and mix the two until they have become a thick, sludge-like material. This is your ferrofluid!
Who invented ferrofluids?
Steve Papell
The first ferrofluid was invented by a NASA engineer named Steve Papell in the early 1960s. His idea was that if you add these magnetic nanoparticles to fuel, you can move it around in zero gravity with a magnetic field. That didn’t really pan out. But since then, ferrofluids have been used far and wide.
What is the meaning of ferrofluid?
Ferrofluid is a liquid that is attracted to the poles of a magnet. It is a colloidal liquid made of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a carrier fluid (usually an organic solvent or water).
Can ferrofluids be controlled by magnets?
Because ferrofluids are very easily magnetized (they have an incredibly high magnetic susceptibility), the peaks can be produced using a small bar magnet. Upon application of an external magnetic field, the nanoparticles align with the field.
How does a Ferrofluidic seal work?
The Ferrofluidics seal uses the response of a magnetic fluid to an externally applied magnetic field. The seal has a permanent magnet, two pole pieces, a magnetically permeable, multi-staged shaft, and the ferrofluid (see drawing). Ferrofluidics use a standard ultra-low vapor pressure synthetic hydrocarbon-based fluid.
Why do ferrofluids Spike?
When a strong magnet is placed near the ferrofluid, spikes are observed. The spikes arise from the tendency of the particles to line up along the magnetic field lines to lower their energy. Surface tension of the fluid, however, limits the extent to which the particles can align themselves with the field.
How do you magnetize iron filings?
Place the magnet at one end of the piece of metal. The magnet must make as much contact with the metal as possible. Place light pressure on the magnet and rub the metal in one direction only. Magnetization will take some time to accomplish so continue rubbing until the iron or steel attracts other pieces of metal.
Why do ferrofluids show superparamagnetic properties?
2.1 The Superparamagnetism Phenomenon If the size of these NPs is small enough, their magnetization can randomly flip direction under the influence of temperature. Superparamagnetic NPs can be dispersed into an aqueous solution and remain stable by coating them with an appropriate layer, thus forming a ferrofluid.
What is a rotary feedthrough?
Rotary feedthroughs are used to transmit rotations from the outside to the inside of the vacuum chamber, for example for moving a shutter or something similar. The off-centre motion of this shaft then drives the rotation inside the vacuum.
What force plays a role with ferrofluids?
In this case, the first two forces (van der Waals and gravity) manifest themselves as surface tension and play a very big role in how the ferrofluid spikes. Obviously, the magnetic force plays a major role in forming the spikes because we only see the spikes when we apply a sufficient magnetic field.
How are ferrofluids prepared in a liquid medium?
Ferrofluids are prepared by suspending tiny particles (10 nm diameter) of magnetic solids in a liquid medium. The liquid medium fluid can be water or an organic solvent. When a magnetic field is applied to a ferrofluid, the entire liquid pulls towards the magnetic field by the nanoparticles attracted to the field.
Why are ferrofluids used in a magnetic field?
Ferrofluids are easy to handle because the fluid location can be controlled through the use of a magnetic field. They can be forced to flow by varying the strength of the magnetic field. Ferrofluids are prepared by suspending tiny particles (10 nm diameter) of magnetic solids in a liquid medium.
Where did the discovery of ferrofluids come from?
Ferrofluids were originally discovered in the 1960s at the NASA Research Center, where scientists were investigating different possible methods of controlling liquids in space.
How are ferrofluids used to improve sound quality?
Ferrofluids are used to improve the performance of speakers and improve sound quality. In a speaker, a coil at the center of the circular magnet is used to carry the electric energy. Due to the magnetic field caused by electrical power, the coil vibrates and produces sound and heat.
