Sciencemadness Discussion Board

Beware eBay aluminum

The WiZard is In - 2-5-2010 at 13:12

5lb Aluminum Powder Flake SMOKE ALUM. (250 Mesh Approx)
Seller tacticalchemical

It's aluminum paste looking up la MSDS —
35% mineral spirits, which explains its odd odour.

The mineral spirits are hard to remove, tired acetone...
problem... due to its small particle size ... it has a v/ v/ high
surface area and absorbs acetone like a sponge. Leaving
it out in the sun for a few days might help, if I had any
sun - sun without strong winds.

It does not work in a thermite composition.

chief - 2-5-2010 at 13:31

Easy aluminum-powder, east-german way:
==> Just stirr the melt when it cools down ..., gives granules of up to 1 mm size, but mostly smaller ...
==> burns at least with MnO2, slowly ... (didn't try any other oxide ...)

:D

[Edited on 2-5-2010 by chief]

hissingnoise - 2-5-2010 at 14:15

Cigarette foil or any delicate alufoil can be ball-milled to a fine flake with lead media.
The thin paper backing will form small balls like cordite grains and these can be filtered out if required but leaving them in doesn't significantly affect the performance. . .

chochu3 - 2-5-2010 at 15:36

ultrasonic some aluminum foil and gather your powdered grey aluminum.

grndpndr - 2-5-2010 at 18:42

are we talking a reloading vibratory brass polisher using the lead balls/other material as media for a fine mesh AL powder?
Thell run forever would seem an obvious solution with the right media?I havent looked to see if thier ultrasonic,they do put a hell of a shine to brass in short order w/polishing media.



[Edited on 3-5-2010 by grndpndr]

chief - 3-5-2010 at 06:03

With melt-stirring the production of Al-powder is easily in the kg-range ...

The WiZard is In - 3-5-2010 at 07:52

Quote: Originally posted by chief  
With melt-stirring the production of Al-powder is easily in the kg-range ...



And now — Something completely different.


Preparation of fine aluminum powders by solution methods
Kelvin T. Higa et al

US Patent 5 885 321

Fine aluminum powders are prepared by decomposing alane-adducts
in organic solvents under an inert atmosphere to provide highly
uniform particles and believed particularly effective as fuels and
additives, in pyrotechnics, and in energetic materials. Effective
adduct species are trialkyl amines...

Inventors: Kelvin T. Higa, Curtes E. Johnson, Richard A. Hollins
Assignee: The United States of America as represented by the
Secretary of the Navy


For da how alulminium powder dobe made I recommend —

Aluminum Powders and Pastes
"The Tale of the Pig"
Reynolds Metals Company
1960

Picric-A - 3-5-2010 at 11:37

Quote: Originally posted by chief  
With melt-stirring the production of Al-powder is easily in the kg-range ...


Please could somebody explain how this 'melt-stirring' method is done to aquire Al-powder in 'kg' quantities?
thanks

The WiZard is In - 3-5-2010 at 13:49

Quote: Originally posted by Picric-A  

Please could somebody explain how this 'melt-stirring' method is done to aquire Al-powder in 'kg' quantities?
thanks



Just a WAG —

Google -> solid-assisted melt disintegration SAMD aluminum.

Nicodem - 3-5-2010 at 14:05

Quote: Originally posted by The WiZard is In  

It's aluminum paste looking up la MSDS —
35% mineral spirits, which explains its odd odour.

The mineral spirits are hard to remove, tired acetone...

Acetone does not dissolve much paraffin oil. Petroleum ether dissolves it efficiently. This is what is generally used to remove oil from oil coated reactive materials (like from NaH/oil mixture).

Fleaker - 3-5-2010 at 14:28

Aluminum metal has a "hot short" state right around a dull red heat, or just as it's cooling. It's very, very brittle at the point and literally crushes like stale potato chips. I suppose you could get some mm sized granules which would be sufficient for further ballmilling.

FrankRizzo - 3-5-2010 at 14:48

Quote: Originally posted by The WiZard is In  
Quote: Originally posted by Picric-A  

Please could somebody explain how this 'melt-stirring' method is done to aquire Al-powder in 'kg' quantities?
thanks



Just a WAG —

Google -> solid-assisted melt disintegration SAMD aluminum.


Thanks Wiz. :)
For those of you too lazy...


Attachment: Solid-assisted melt disintegration (SAMD), a novel technique for metal powder production.pdf (1.4MB)
This file has been downloaded 708 times

[Edited on 5/3/2010 by FrankRizzo]

The WiZard is In - 3-5-2010 at 16:02

Quote: Originally posted by FrankRizzo  



Thanks Wiz. :)
For those of you too lazy...



I was going to suggest

http://www.justfuckinggoogleit.com/ [A legit URL]

chief - 4-5-2010 at 03:07

Quote: Originally posted by Picric-A  
Quote: Originally posted by chief  
With melt-stirring the production of Al-powder is easily in the kg-range ...


Please could somebody explain how this 'melt-stirring' method is done to aquire Al-powder in 'kg' quantities?
thanks


Well, I did it like this:
==> Had a melt (electric furnace)
==> stirred it with some more aluminum ...

The Al-Stirring-rod melted until the temp was down to the melting point ... (saving a lot of time by quickly cooling to the right temperature :D)
==> Then 10 or 15 more minutes of stirring

... gives Al-Powder ...

It works because the air oxidizes the Al-surface, and with the stirring air gets everywhere into the melt ... ; the oxide-layer isolates the droplets, result is a fine powder ...

==========

Only it's _work_ to stirr the melt by hand, so on subsequent runs I used a drilling-engine with some iron-rod ... and threw Al-pieces into the melt until it nearly was at 651 [Cels] ...

==========

When everything was a fine powder and the temp below the melting point I used to quickly get it out of the furnace, to avoid any sintering or whatever ...
==> ... that's when it sometiomes can ignite, at least the finer fractions ...

Generally a thing to be done outside, because of the vapors..., but it will work with a 10- or 50-kg melt as well ...

[Edited on 4-5-2010 by chief]

[Edited on 4-5-2010 by chief]

Picric-A - 4-5-2010 at 04:41

Surly the oxide coating will leave the powder relativly unreactive compared to Al powder that has been ground down, thus it will be useless for things like thermite?

chief - 4-5-2010 at 14:18

It works fine with MnO2 ...; didn't try anything else ...

Microtek - 9-5-2010 at 23:57

If the Al powder is to be used for themite there is another way:

Use Al foil as is.
Determine how much Al is in one meter of foil, then roll out however much you require. Figure out how much oxide you need based on a suitable stoichiometry, then sprinkle it onto the Al foil. Then roll the foil into a long "sausage" or tube while crimping or twisting it with your hands to make sure the oxide stays where it is.
Stuff the "sausage" into a suitable container, but make sure there is room enough for a booster of traditional powder thermite, as this is quite difficult to ignite.

I had this idea when I read somewhere that Al and Fe2O3 reacts in the liquid phase in the thermite reaction, which would imply that finely powdered reagents only really promote ease of ignition and burn rate. I've tested it a number of times and it seems to work just fine.
Of course by this reasoning, you could also add big chunks of aluminum scrap as long as there was enough regular thermite to get it molten.

chief - 10-5-2010 at 05:21

Al-foil: This works ! :D

... wrote a small but useful program to calculate the mass of MnO2 (Al-MnO2-thermite), to be compiled with a fortran-compiler:



Attachment: MnO2_Al_therm.F (652B)
This file has been downloaded 612 times

peach - 13-5-2010 at 14:29

Quote: Originally posted by chochu3  
ultrasonic some aluminum foil and gather your powdered grey aluminum.


You've Mc Owned the thread in one sentence, I hope you're proud! :)

Guess it doesn't produce it at a particularly high rate.

Ask the guys who sell materials for home brewing fireworks, they've got mountains of the stuff and in every form, grain size or mesh you'll ever want.

Here's one example I've been drooling over since I was about 13;

http://www.skylighter.com/

[Edited on 13-5-2010 by peach]