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Homemade Ferrofluid

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Heiders

Tue Mar 07 2006, 05:15AM

Registered Member #268 Joined: Tue Feb 28 2006, 02:44AM
Location: Ontario, Canada
Posts: 48

SUCCESS!!!! I have spikes and everything!

Granted, they are small, but I'm excited. They are anywhere from 1-6mm, roughly. Depends on which magnet and how far away it is, as well as how much magnetite has been dragged up the side.

I have made 4 batches of ferrofluid. The first two were unfettered disasters. The third one gave me a blob, but it was black, so I took it as a good sign and moved on to changing the recipe, now having a "feel" for how it worked.

The fourth trial was the one that was split into two batches. They were recombined after showing no good results and filtered. I got a blackish sludge with a silt-like appearance (haven't touched it yet) in my filter paper. This responds to the magnet, whereas the filtered liquid doesn't appear to repond almost at all! Unless I was supposed to keep the stuff in the papers, which doesnt make sense... (It's in a jar anyway)

When my brother came home from university tonight (his hands in photos), he wanted to see my progress, so I brought up trials 3&4. After a little playing around, we noticed small bumps on the wall of jar #3. Long story short, having the magnet against the glass is TOO close, and pulls the particles too strongly. Having it on different angles (it's a ring magnet) and varying distances helped form what you see below.

However: Only the bottom "sludge" is really attracted, and when shaken, the fluid doesnt give spikes! It's too thin. I need to settle out the good particles without losing too much of the bottom stuff. I considered letting it settle, then putting a ring magnet underneath and sucking off the top, but before I do that (and lose a LOT of magnetite suspended in that) I want to pour the whole lot out really thin, like in a glass baking dish.

All the demos on the internet that I have seen used a very thin flat layer, and that was how mine responded, in a thin layer on the side. I have already appropriated my mom's pyrex measuring cup, but she WILL NOT give me a baking dish. So I'm off to Value Village again for a glass dish. More updates after I get there, not too sure when!

Chris

Tue Mar 07 2006, 05:19AM

Registered Member #8 Joined: Thu Feb 02 2006, 04:34AM
Location: Harlowton, MT, United States
Posts: 214

Yay! That's a bit more like it.

What methods did you use?

For all the nay-sayers out there who claim that "homemade ferrofluid doesn't spike"... hah

Part Scavenger

Tue Mar 07 2006, 01:58PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

Way to go Heidi! I can't wait to get back to trying. I haven't had 5 min since last Tues. Are you still using the lemony fresh ammonia?

How do you think you made batch 3? Do you think letting it sit had anything to do with it?

Heiders

Thu Mar 09 2006, 04:19AM

Registered Member #268 Joined: Tue Feb 28 2006, 02:44AM
Location: Ontario, Canada
Posts: 48

Unsuprisingly, Andrew's formula is quite good. Clearly he tried it several times with success. It is that formula that I used for batch 3 : the difference between working and not working is the things like how long to cook it and what it's supposed to look like when you're done each step.

When I cooked it, I originally thought I had overcooked it, because it clumped into a big, fairly stiff blob in the water leftover.

The next batch I only cooked until it looked like it was ABOUT to clump (starting to make small chunks) and took it off the heat. Anyone else get this clumping deal? It did only take ~15-20 min to cook to this point, and I was cold and it wasn't changing anymore, and I couldn't smell anything because I was sick, so I brought it back inside and poured off the water. This batch didn't work, so I think it's worse to undercook than overcook.

Yes, I think letting it sit probably had something to do with it, I don't know how long is optimal. I thought even the best ferrofluid eventually separates (to some extent) so letting it sit for too long will probably be worse. We can only try at regular intervals to see what the best timing is!

I will do another batch in the next couple days because my internet is currently down and I have lots of free time. I'm posting from a borrowed dialup laptop. Yes, I am still using lemony ammonia. I dont think It should make too much of a difference, Andrew stated "household ammonia" and I'm really starting to trust him on this

See you all in 3-5 days, when my internet comes back.

...

Wed Mar 15 2006, 05:54AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

well it has been 6 days now...

Any of you guys made more progress? So far Heiders 6mm spikes are the thing to beat...

Part Scavenger

Wed Mar 15 2006, 03:14PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

No, I haven't had 1 1/2 hrs continous in two and a half weeks. Then I go out of town tomorrow.

I've been dying to try another batch, but I'll have to wait two weeks I guess. How about you Heidi?

Heiders

Fri Mar 17 2006, 10:17PM

Registered Member #268 Joined: Tue Feb 28 2006, 02:44AM
Location: Ontario, Canada
Posts: 48

*cheers* Yay, now I'm not double posting!

I poured out my batch #3 into my mom's glass pie plate, dragged a magnet around on the bottom to pick up all the magnetite, and poured off the excess liquid. This is the really magnetic stuff, but it dries out really fast. So I took advantage of that by setting up a magnet under the plate and leaving it overnight. Next day, remove magnet and dried spikes stay! Picture below.

Anyway. I have really only had to make one change to the recipe. I think it has to do with the concentration of my ammonia, because anything less than about 250mL (total) will not react out all the magnetite. From another test I ran, I found that if the solution is not completely black BEFORE cooking, it will NOT work. Also: adding ammonia after cooking with oleic will not react all the remaining FeCl3/2 solution. Picture below is about 24h after excess ammonia was added, enough to fully react the solution. (though it separates in about 2h)

I am wondering if I should be adding more oleic or not. It seems logical, the ammonia and oleic are in a 30:1 ratio in the recipe, but if it's just the concentration of my ammonia that is too low, does it need more oleic? Will it just react as the excess reactant or will it hang around and change the properties of the end susbstance? hmmmm!

Happy St. Patrick's Day!

Conundrum

Fri Mar 24 2006, 10:30AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

(snipped from "NS" article)

The idea relies on simple high-school physics: move a magnet close to a copper coil and the changing magnetic field experienced by the coil will induce an electric current to flow through it. Cheung placed a magnet in a tube filled with ferrofluid, wrapped a coil around the tube, and stuck a magnet at each end to keep the magnet inside moving. The result is a system that turns random motion into electricity, with almost no loss of energy to friction. The key is the exceptional slipperiness of the ferrofluid coating - around 40 times as slippery as ice.

this is interesting, perhaps someone can try this?
-A

Nik

Mon Mar 27 2006, 04:01AM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

Please keep in mind that talk of free energy and perpeual motion is not permitted on 4hv. I see no reason for the magnet inside to keep moving.

ragnar

Mon Mar 27 2006, 05:21AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Nik. You're not making any sense. Where's the pseudoscience?

No perpetual motion involved - it just happens that the magnet will slow down to a stop after converting almost all of its kinetic energy into stored electrical energy, as opposed to rubbing against and heating up the walls of the container.

Of course, the bigger the 'load' on the inductor, the slower your magnet will go as a result of Lenz' law and magnetic braking.

The experiment Conundrum is describing has the magnet in a flux-friendly almost frictionless carrier, so that even the tiniest random motion can move the magnet.

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