Ferrofluids are made up of tiny magnetic fragments of iron suspended in oil (often kerosene) with a surfactant to prevent clumping (usually oleic acid). The fluid is relatively easy to make at home yet extremely expensive to buy on-line. How does $165 a liter sound? Pretty bad, right?
What happens is that when a magnetic field is applied to the fluid, the particles of iron compound inside align to it. Once that happens, the fluid becomes a fluid-solid.
The ability to become solid or liquid with the application of a magnetic field also makes them perfect for computer assisted shock absorbers in Ferraris; NASA uses them for high-tech flight altitude assistance, and like a gyroscope in spacecraft. The Air Force uses their magnetic field absorbing properties to make aircraft invisible to radar.
A fantastic demo is here:
http://www.youtube.com/v/me5Zzm2TXh4And a tutorial on how to make some for yourself very cheaply is here:
http://chemistry.about.com/od/demonstrationloveperiments/ss/liquidmagnet.htmAfter watching that video, my mind was blown.
I will try making a batch eventually.
Thoughts?
