Magnetic Fluids

Polo writes: "Remember those magnetic sculpture things you can buy at the mall where these small metal pieces stay in one shape. Imagine doing that with Ferrofluids. This is just too cool. Dan is the nerd's nerd." Well, can't get any higher praise that that, I suppose. :) I have a couple of neodymium magnets and yes, they are much fun. Never played with magnetic fluid though.

Comments

SIGGRAPH

[LS]

Japanese artists Sachiko Kodama and Minako Takeno did an art piece displayed at SIGGRAPH using ferrofluids. Memepool had some links about this back in august.

LS

ferrofluids, magnetic clutches

[sfbanutt]

Ferrofluids have been used in magnetic clutches. You have two plates facing each other with vanes on them. Put them in a ferrofluid tank. When the magnetic field is absent, either shaft will spin freely without effecting the other. Add a magnetic field and WHAM, the shafts are locked together. I seem to remember there being a problem getting a decent amount of shear strength though. There was an article on this in Scientific American a few years back in the Amateur Scientist column.

Dialing "Guinness"...

[cribcage]

The "nerd's nerd" couldn't handle three measly hits? This has to be a "slashdotting" record. ;-)

crib

Ferrofluid links

[Black Acid]

Ferrofluids are indeed cool but DansData is not the only place which has information on them. They can be used to create nanostructures and defy gravity for environmental engineering. In case you're wondering what exactly ferrofluids are, here's a good excerpt from the previous link:

Ferrofluids are colloidal suspensions of nanoscale magnetic particles in a carrier fluid; the particles form magnetic domains separated by coats of dispersant only a molecule thick. These magnetic fluids have been used in many ways--to form airtight seals around rapidly moving parts, to move drugs in the bloodstream and rocket propellants in spacecraft, even to cool and dampen powerful audio speakers. Now steerable ferrofluids may give rise to new tools for subsurface environmental engineering and laboratory safety.

At Berkeley, they use magnetic fluids to control movement of underground fluids without any contact. Interesting stuff. For an introduction to ferrofluids, see University of Wisconsin's excellent article.

Ferrofluids

[smunt]

check this link. It's the first link on the page (which is unreachable by now).

aHA!

[Soko]

I have a couple of neodymium magnets and yes, they are much fun. Never played with magnetic fluid though.


That explains the form errors trying to reply to this story.

Umm, Michael? Could you keep your fscking magnets away from the fscking servers? Thanks.

Soko

Some other links:

[morcheeba]

Check out this cool picture from Science Friday.

And a meatspace link: check out ferrofluids for yourself at the exploratorium -- if the exhibit is still there (it was maybe 4 years ago, upstairs), they have a tank of ferrofluid (with I think a lighter different-colored fluid floating on top). Pressing the buttons activates different electromagnets under the fluid, and it forms bumps on the surface (maybe protruding through the different colored liquid, as in the picture above, if I remember right). It's neat to see the surface of a liquid that is not flat, yet not moving. The exploratorium is well worth the visit if you're in the SF bay area.

Again, Spherical Magnets

[FFFish]

Lee Valley Tools, besides being a generally cool place with some delightful woodworking tools, has spherical magnets.

And, no, to presuppose the silly question I was asked earlier, of course one of the poles isn't in the centre of the magnet. If it were, how the hell would the flux lines get to the outside?!

These would be the equivalent of a bar magnet lathed spherical, allowing them to roll around and do other neat shit.

FWIW, Lee Valley also has awesome rare-earth disc magnets. I've got a handful of them. They can suck through a good 2" of wood. Damn near impossible to get off the fridge door. Does nasty shit to any nearby wallets, too. And don't even think about letting them near your monitor.

Mirror for the video

[Skaven04]

I got the video downloaded just in time...

here

Re:how long will it take

[camusflage]

We won't see any infomercials for this stuff. Toxic, flammable, corrosive and mutagenic are just a few of the drawbacks. Add to it that the resultant fluid will "permanently stain almost any fabric".

Magnetic Fluids

[Anonymous Coward]

Fluids influenced by magnets have been around for a while.

One of the problems facing the space program in its earliest days was how to re-fire liquid fueled rockets in a weightless environment. If you think about it, just exactly how do you get the fluids in a tank half full of rocket fuel to take a position over and in the sump of the tank so the pumps can supply reliable measures of fuel and oxidizer to the engines combustion chamber.

The innovative solution was to mix the fuel and oxidizer with a ferrous based additive so that a large magnet at the sump of the tank would draw the fuel and oxidizer to the sump. This isn't a magnetic fluid but it is one of the ingenious solutions to a myriad of engineering challenges facing our space program.

Where to score some black magnetic goo.

[napa1m]

A few friends and I bought a large bottle of the stuff, it's pretty neat to play with along with some magnets, but you need some SERIOUS power to get any real decent results, initially we were messing around with some discarded large speaker magnets and voice coils (fixed magnetic power). We went so far as to have ordered some higher power electromagnets and some extra hardware to control their strength. Unfortunately due to the recent events in our neighborhood (NYC) we haven't had a chance to experiment much more lately.

Oh and its more like liquid than goo, so dont get your hopes of creating a giant black goo monster up too high.

Anyway, if you want to pick some up for yourself try these places:

Edmund Scientific
(also has magnets, electromagnets)

Teacher Source
(this is where we got our large 1000ml bottle)

and more listed at the official ferroftec web site:
ferrofluidics

-nA

Re:trying this stuff

[micromoog]

Anyone know how many turns of a coil runnig at 1Amp you'd need to make a 1cm by 1cm crosssection of this sort of stuff remain rigid against a newton of shear?

42.